{ "batch": "27-audio-for-video", "articles": [ { "id": "learn_r27_audio_for_video_loudness_ebu_r128_target", "category": "Studio", "title": "EBU R 128 programme loudness target", "summary": "EBU R 128 requires programme loudness to be normalised to a target level of -23.0 LUFS.", "body": "EBU R 128 requires programme loudness to be normalised to a target level of -23.0 LUFS.\n\nWhat European Broadcasting Union (EBU) actually says:\n\n“that the Programme Loudness Level shall be normalised to a Target Level of −23.0 LUFS.”\n\nNote: R 128 version 5.0, November 2023. LUFS = Loudness Units relative to Full Scale.", "source_type": "official", "source_link": "https://tech.ebu.ch/docs/r/r128.pdf", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "European Broadcasting Union (EBU)", "evidence_quote": "that the Programme Loudness Level shall be normalised to a Target Level of −23.0 LUFS.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Loudness normalisation", "topic": "EBU R 128 programme loudness target", "applies_to_country": "*", "applies_to_scope": "European Broadcasting Union recommendation; adopted widely in European broadcast delivery. Not a target for streaming-pl", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_loudness_ebu_r128_tolerance", "category": "Studio", "title": "Loudness normalisation: EBU R 128 permitted deviation from target", "summary": "EBU R 128 permits a tolerance of plus or minus 1.0 LU from the -23.0 LUFS target where the target is not practically achievable, such as in live programmes.", "body": "EBU R 128 permits a tolerance of plus or minus 1.0 LU from the -23.0 LUFS target where the target is not practically achievable, such as in live programmes.\n\nWhat European Broadcasting Union (EBU) actually says:\n\n“Where attaining the Target Level is not achievable practically (for example, live programmes), a tolerance of ±1.0 LU is permitted.”\n\nNote: The R 128 version-history table separately records that in version 3.0 (2014) the tolerance was restricted to +/- 0.5 LU; the current recommendation text says ±1.0 LU. Recorded as it reads in the current document.", "source_type": "official", "source_link": "https://tech.ebu.ch/docs/r/r128.pdf", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "European Broadcasting Union (EBU)", "evidence_quote": "Where attaining the Target Level is not achievable practically (for example, live programmes), a tolerance of ±1.0 LU is permitted.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Loudness normalisation", "topic": "EBU R 128 permitted deviation from target", "applies_to_country": "*", "applies_to_scope": "Applies to the Programme Loudness Level; the tolerance is conditional on practical impossibility, not a general allowanc", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_loudness_ebu_r128_truepeak", "category": "Studio", "title": "Loudness normalisation: EBU R 128 maximum true peak", "summary": "EBU R 128 requires that the true peak level of a programme not exceed -1 dBTP during production of linear audio.", "body": "EBU R 128 requires that the true peak level of a programme not exceed -1 dBTP during production of linear audio.\n\nWhat European Broadcasting Union (EBU) actually says:\n\n“that the True Peak Level of a programme shall not exceed −1 dBTP (dB True Peak) during production (linear audio)”\n\nNote: True peak is measured per ITU-R BS.1770, which oversamples to catch inter-sample peaks that a sample-peak meter misses.", "source_type": "official", "source_link": "https://tech.ebu.ch/docs/r/r128.pdf", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "European Broadcasting Union (EBU)", "evidence_quote": "that the True Peak Level of a programme shall not exceed −1 dBTP (dB True Peak) during production (linear audio)", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Loudness normalisation", "topic": "EBU R 128 maximum true peak", "applies_to_country": "*", "applies_to_scope": "Stated for linear (uncompressed) audio during production.", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_loudness_itu_bs1770_lkfs", "category": "Studio", "title": "Loudness normalisation: Meaning of the LKFS unit", "summary": "LKFS stands for Loudness, K-weighted, relative to nominal full scale, and one LKFS corresponds to one decibel of level change.", "body": "LKFS stands for Loudness, K-weighted, relative to nominal full scale, and one LKFS corresponds to one decibel of level change.\n\nWhat International Telecommunication Union (ITU-R) actually says:\n\n“The LKFS unit is equivalent to a decibel in that an increase in the level of a signal by 1 dB will cause the loudness reading to increase by 1 LKFS.”\n\nNote: The document also states the designation directly: \"This designation signifies: Loudness, K-weighted, relative to nominal full scale.\"", "source_type": "official", "source_link": "https://www.itu.int/dms_pubrec/itu-r/rec/bs/R-REC-BS.1770-5-202311-I!!PDF-E.pdf", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "International Telecommunication Union (ITU-R)", "evidence_quote": "The LKFS unit is equivalent to a decibel in that an increase in the level of a signal by 1 dB will cause the loudness reading to increase by 1 LKFS.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Loudness normalisation", "topic": "Meaning of the LKFS unit", "applies_to_country": "*", "applies_to_scope": "LKFS and LUFS are the same unit under two names; ITU uses LKFS, EBU uses LUFS.", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_loudness_ebu_r128s2_streaming", "category": "Studio", "title": "EBU guidance for streaming distribution loudness", "summary": "EBU R 128 Supplement 2 recommends that programmes be streamed unchanged at -23.0 LUFS, and gives an interim Distribution Loudness Level range of -20.0 to -16.0 LUFS.", "body": "EBU R 128 Supplement 2 recommends that programmes be streamed unchanged at -23.0 LUFS, and gives an interim Distribution Loudness Level range of -20.0 to -16.0 LUFS.\n\nWhat European Broadcasting Union (EBU) actually says:\n\n“the interim value for the Distribution Loudness Level should be in the range of −20.0 to −16.0 LUFS”\n\nNote: The same document states \"programmes should be streamed unchanged, that is at −23.0 LUFS\". This is the closest thing to a standards-body figure for the loudness band that consumer streaming platforms actually sit in.", "source_type": "official", "source_link": "https://tech.ebu.ch/docs/r/r128s2.pdf", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "European Broadcasting Union (EBU)", "evidence_quote": "the interim value for the Distribution Loudness Level should be in the range of −20.0 to −16.0 LUFS", "volatility": "medium", "from_batch": "27-audio-for-video", "subject": "Loudness normalisation", "topic": "EBU guidance for streaming distribution loudness", "applies_to_country": "*", "applies_to_scope": "The -20 to -16 LUFS band is explicitly an interim value for a Distribution Loudness Level, not a production target.", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_loudness_spotify_target", "category": "Studio", "title": "Spotify loudness normalisation target", "summary": "Spotify normalises tracks to -14 dB LUFS, measured according to the ITU 1770 standard.", "body": "Spotify normalises tracks to -14 dB LUFS, measured according to the ITU 1770 standard.\n\nWhat Spotify actually says:\n\n“We adjust tracks to -14 dB LUFS, according to the ITU 1770 standard.”\n\nNote: Page carries no visible publication or revision date. Quote reproduced with the source's bold markup removed.", "source_type": "official", "source_link": "https://support.spotify.com/us/artists/article/loudness-normalization/", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Spotify", "evidence_quote": "We adjust tracks to -14 dB LUFS, according to the ITU 1770 standard.", "volatility": "medium", "from_batch": "27-audio-for-video", "subject": "Loudness normalisation", "topic": "Spotify loudness normalisation target", "applies_to_country": "*", "applies_to_scope": "Spotify music catalogue. Spotify states this is applied by the platform, so uploading louder or quieter material does no", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_loudness_applepodcasts_target", "category": "Studio", "title": "Apple Podcasts loudness target", "summary": "Apple Podcasts states that overall loudness should remain around -16 dB LKFS with a plus or minus 1 dB tolerance, calculated per ITU-R BS.1770-5.", "body": "Apple Podcasts states that overall loudness should remain around -16 dB LKFS with a plus or minus 1 dB tolerance, calculated per ITU-R BS.1770-5.\n\nWhat Apple actually says:\n\n“the overall loudness remains around -16 dB LKFS, with a +/- 1 dB tolerance”\n\nNote: Page carries no visible publication date.", "source_type": "official", "source_link": "https://podcasters.apple.com/support/893-audio-requirements", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Apple", "evidence_quote": "the overall loudness remains around -16 dB LKFS, with a +/- 1 dB tolerance", "volatility": "medium", "from_batch": "27-audio-for-video", "subject": "Loudness normalisation", "topic": "Apple Podcasts loudness target", "applies_to_country": "*", "applies_to_scope": "Apple Podcasts audio requirements. This is the most directly relevant published target for a person publishing spoken-wo", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_loudness_applepodcasts_truepeak", "category": "Studio", "title": "Loudness normalisation: Apple Podcasts true peak limit", "summary": "Apple Podcasts requires that the true-peak value not exceed -1 dB FS, calculated per ITU-R BS.1770-5.", "body": "Apple Podcasts requires that the true-peak value not exceed -1 dB FS, calculated per ITU-R BS.1770-5.\n\nWhat Apple actually says:\n\n“the true-peak value doesn't exceed -1 dB FS”\n\nNote: The page also states: \"The LKFS and true-peak values are calculated according to the ITU-R BS.1770-5 recommendation\".", "source_type": "official", "source_link": "https://podcasters.apple.com/support/893-audio-requirements", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Apple", "evidence_quote": "the true-peak value doesn't exceed -1 dB FS", "volatility": "medium", "from_batch": "27-audio-for-video", "subject": "Loudness normalisation", "topic": "Apple Podcasts true peak limit", "applies_to_country": "*", "applies_to_scope": "Apple Podcasts audio requirements.", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_distance_inverse_square_law", "category": "Studio", "title": "[Unverified - being checked] Mic-to-mouth distance: Inverse square law applied to a sound source", "summary": "[Unverified - being checked] Doubling the distance between a sound source and a microphone drops the level of that source by six decibels.", "body": "Doubling the distance between a sound source and a microphone drops the level of that source by six decibels.\n\nWhat Shure actually says:\n\n“Because of the Inverse Square Law of Sound, if the distance between the sound source and the microphone is doubled, the level of the sound source drops by six decibels at this greater distance.”\n\nNote: Run in reverse, this is why halving mic-to-mouth distance is the single highest-leverage change available: it raises the wanted signal by 6 dB with no equipment purchase.", "source_type": "official", "source_link": "https://www.shure.com/en-EU/insights/top-8-microphone-myths-exposed", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Shure", "evidence_quote": "Because of the Inverse Square Law of Sound, if the distance between the sound source and the microphone is doubled, the level of the sound source drops by six decibels at this greater distance.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Mic-to-mouth distance", "topic": "Inverse square law applied to a sound source", "applies_to_country": "*", "applies_to_scope": "Strictly true for the direct sound field. In a reverberant room the effect flattens beyond the critical distance.", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" }, "verification": { "status": "unverified", "label": "Unverified - being checked", "reasons": [ "legal_fetch_over_cap" ], "checked_utc": "20261021-123916Z" } }, { "id": "learn_r27_audio_for_video_distance_ambient_noise_constant", "category": "Studio", "title": "Why distance changes signal-to-noise, not just level", "summary": "Shure states that when microphone distance from the source changes, the ambient noise level stays the same, so only the wanted signal changes.", "body": "Shure states that when microphone distance from the source changes, the ambient noise level stays the same, so only the wanted signal changes.\n\nWhat Shure actually says:\n\n“The ambient noise stays the same.”\n\nNote: Short quote; the surrounding passage is about the effect of increasing source-to-mic distance. The page also notes microphones \"only measure the sound that travels to the diaphragm.\"", "source_type": "official", "source_link": "https://www.shure.com/en-EU/insights/top-8-microphone-myths-exposed", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Shure", "evidence_quote": "The ambient noise stays the same.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Mic-to-mouth distance", "topic": "Why distance changes signal-to-noise, not just level", "applies_to_country": "*", "applies_to_scope": "This is the mechanism by which moving closer improves signal-to-noise ratio; it is why turning up the gain is not equiva", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_acoustics_critical_distance", "category": "Studio", "title": "Room acoustics: Critical distance", "summary": "Critical distance is the distance at which the direct and reverberant sound fields have equal sound pressure level for a directional source.", "body": "Critical distance is the distance at which the direct and reverberant sound fields have equal sound pressure level for a directional source.\n\nWhat Acoustical Society of America (ASA/ANSI Acoustical & Bioacoustical Terminology Database) actually says:\n\n“Distance at which the sound pressure level of the direct and the reverberant sound fields are equal when dealing with a directional source. Unit, meter (m).”\n\nNote: The entry's annotation adds: \"The critical distance is dependent on the geometry and absorption of the space in which the sound waves propagate, as well as the dimensions and shape of the sound source.\"", "source_type": "official", "source_link": "https://asastandards.org/terms/critical-distance/", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "Acoustical Society of America (ASA/ANSI Acoustical & Bioacoustical Terminology Database)", "evidence_quote": "Distance at which the sound pressure level of the direct and the reverberant sound fields are equal when dealing with a directional source. Unit, meter (m).", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Room acoustics", "topic": "Critical distance", "applies_to_country": "*", "applies_to_scope": "Beyond the critical distance, moving the mic further away stops reducing the direct-to-reverberant ratio much, because r", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_pattern_omnidirectional", "category": "Studio", "title": "Microphone polar patterns: Omnidirectional pattern", "summary": "An omnidirectional microphone is equally sensitive to sound arriving from all angles.", "body": "An omnidirectional microphone is equally sensitive to sound arriving from all angles.\n\nWhat Shure actually says:\n\n“Omni mics are equally sensitive to sound arriving from all angles.”\n\nNote: Because an omni rejects nothing, distance is the only variable available to it for improving direct-to-reverberant ratio.", "source_type": "official", "source_link": "https://www.shure.com/en-US/insights/microphone-directionality-polar-pattern-basics", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Shure", "evidence_quote": "Omni mics are equally sensitive to sound arriving from all angles.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Microphone polar patterns", "topic": "Omnidirectional pattern", "applies_to_country": "*", "applies_to_scope": "Most phone and laptop built-in mics, and most lavalier mics, are omnidirectional. An omni cannot be aimed away from a fr", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_pattern_cardioid", "category": "Studio", "title": "Microphone polar patterns: Cardioid pattern rejection angle", "summary": "A cardioid microphone has a wide on-axis pickup area and its maximum rejection is at 180 degrees off-axis, directly behind the microphone.", "body": "A cardioid microphone has a wide on-axis pickup area and its maximum rejection is at 180 degrees off-axis, directly behind the microphone.\n\nWhat Shure actually says:\n\n“They have a wide on-axis pick-up area and maximum rejection at 180 degrees off-axis.”", "source_type": "official", "source_link": "https://www.shure.com/en-US/insights/microphone-directionality-polar-pattern-basics", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Shure", "evidence_quote": "They have a wide on-axis pick-up area and maximum rejection at 180 degrees off-axis.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Microphone polar patterns", "topic": "Cardioid pattern rejection angle", "applies_to_country": "*", "applies_to_scope": "Practical consequence: the null points at whatever is directly behind the mic, so a cardioid is aimed with its back to t", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_pattern_shotgun_interference_tube", "category": "Studio", "title": "How a shotgun (interference tube) microphone works", "summary": "An interference tube (shotgun) microphone consists of a first-order cardioid element plus a tube, and the tube increases directivity only from a given frequency upwards.", "body": "An interference tube (shotgun) microphone consists of a first-order cardioid element plus a tube, and the tube increases directivity only from a given frequency upwards.\n\nWhat DPA Microphones actually says:\n\n“In principle, the interference tube microphone consists of the 1st-order cardioid element and the tube.”\n\nNote: The page also states \"the interference tube increases directivity from a given frequency and up\", and that \"It is actually the inner mesh and its density that are responsible\" for the directivity rather than the outer slits. The page makes no claim about shotguns reducing reverberation.", "source_type": "official", "source_link": "https://www.dpamicrophones.com/mic-university/technology/how-to-specify-the-directivity-of-a-shotgun-mic/", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "DPA Microphones", "evidence_quote": "In principle, the interference tube microphone consists of the 1st-order cardioid element and the tube.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Microphone polar patterns", "topic": "How a shotgun (interference tube) microphone works", "applies_to_country": "*", "applies_to_scope": "Because the tube only works above a certain frequency, a shotgun is close to a plain cardioid at low frequencies. It nar", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_pattern_directional_rear_attenuation", "category": "Studio", "title": "How much a directional microphone actually rejects", "summary": "DPA states that sounds arriving from the rear of a directional microphone are attenuated at maximum by some 30 dB, and that this attenuation depends on frequency.", "body": "DPA states that sounds arriving from the rear of a directional microphone are attenuated at maximum by some 30 dB, and that this attenuation depends on frequency.\n\nWhat DPA Microphones actually says:\n\n“Sounds from the rear are at its maximum attenuated by some 30 dB but this attenuation is dependent of frequency.”\n\nNote: Quote reproduced with the source's own grammar.", "source_type": "official", "source_link": "https://www.dpamicrophones.com/mic-university/technology/directional-vs-omnidirectional-microphones/", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "DPA Microphones", "evidence_quote": "Sounds from the rear are at its maximum attenuated by some 30 dB but this attenuation is dependent of frequency.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Microphone polar patterns", "topic": "How much a directional microphone actually rejects", "applies_to_country": "*", "applies_to_scope": "30 dB is the best case at the null and at favourable frequencies, not a flat figure across the spectrum. It is the ceili", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_pattern_directional_wind_pop_sensitivity", "category": "Studio", "title": "Microphone polar patterns: Directional microphones and wind/pop sensitivity", "summary": "Directional microphones are far more sensitive to wind and pop noise than omnidirectional microphones because their diaphragms are more compliant.", "body": "Directional microphones are far more sensitive to wind and pop noise than omnidirectional microphones because their diaphragms are more compliant.\n\nWhat DPA Microphones actually says:\n\n“Directional microphones are far more sensitive to wind and pop noises than omnidirectional microphones, due to the use of more compliant diaphragms on directional microphones.”\n\nNote: The same page notes directional mics also \"tend to distort more than omnidirectional microphones\" and that a cardioid \"suffers from the so-called proximity effect; close to the source the lower frequencies are boosted\".", "source_type": "official", "source_link": "https://www.dpamicrophones.com/mic-university/technology/directional-vs-omnidirectional-microphones/", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "DPA Microphones", "evidence_quote": "Directional microphones are far more sensitive to wind and pop noises than omnidirectional microphones, due to the use of more compliant diaphragms on directional microphones.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Microphone polar patterns", "topic": "Directional microphones and wind/pop sensitivity", "applies_to_country": "*", "applies_to_scope": "A direct trade-off: the pattern that rejects the room is the pattern that needs a pop filter and a windshield most.", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_lav_placement_distance", "category": "Studio", "title": "Lavalier placement distance", "summary": "Rode advises positioning a lavalier microphone on the chest about a hand-span, 20 to 30 cm, from the mouth.", "body": "Rode advises positioning a lavalier microphone on the chest about a hand-span, 20 to 30 cm, from the mouth.\n\nWhat RØDE actually says:\n\n“position the mic on the chest, about a hand-span distance (20-30cm) from the mouth”\n\nNote: Note the interaction with the inverse-square law: a lav at 25 cm is roughly 6 dB down on a mic at 12 cm, but still far closer than a phone held at arm's length.", "source_type": "official", "source_link": "https://rode.com/en-us/about/news-info/how-to-use-a-lavalier-mic", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "RØDE", "evidence_quote": "position the mic on the chest, about a hand-span distance (20-30cm) from the mouth", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Lavalier microphones", "topic": "Lavalier placement distance", "applies_to_country": "*", "applies_to_scope": "Manufacturer placement guidance; not a measured study.", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_lav_clothing_rustle", "category": "Studio", "title": "Lavalier microphones: Clothing contact noise", "summary": "Rode advises keeping a lavalier microphone clear of any clothing that may rub against it, because such rubbing will be audible.", "body": "Rode advises keeping a lavalier microphone clear of any clothing that may rub against it, because such rubbing will be audible.\n\nWhat RØDE actually says:\n\n“keep the mic clear from any other piece of clothing that may rub against it, as this will be audible”\n\nNote: The page's summary sentence: \"Provided the mic is 20-30cm from your mouth, and does not have clothing rubbing against it, you will get a great result\".", "source_type": "official", "source_link": "https://rode.com/en-us/about/news-info/how-to-use-a-lavalier-mic", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "RØDE", "evidence_quote": "keep the mic clear from any other piece of clothing that may rub against it, as this will be audible", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Lavalier microphones", "topic": "Clothing contact noise", "applies_to_country": "*", "applies_to_scope": "This is the dominant practical failure mode of lavaliers, and it is not fixable in post.", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_acoustics_rt60_definition", "category": "Studio", "title": "Room acoustics: Reverberation time (RT60) definition", "summary": "Reverberation time is the time required for the level of the time-mean-square sound pressure in an enclosure to decrease by 60 dB after the source has stopped, for a stated frequency or frequency band.", "body": "Reverberation time is the time required for the level of the time-mean-square sound pressure in an enclosure to decrease by 60 dB after the source has stopped, for a stated frequency or frequency band.\n\nWhat Acoustical Society of America (ASA/ANSI Acoustical & Bioacoustical Terminology Database) actually says:\n\n“Of an enclosure, for a stated frequency or frequency band, time that would be required for the level of the time-mean-square sound pressure in the enclosure to decrease by 60 dB, after the source has been stopped. Unit, second (s); symbol T60.”\n\nNote: ISO 3382 is the measurement standard but is paywalled; this ASA/ANSI terminology entry is the freely readable tier-A definition.", "source_type": "official", "source_link": "https://asastandards.org/terms/reverberation-time/", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "Acoustical Society of America (ASA/ANSI Acoustical & Bioacoustical Terminology Database)", "evidence_quote": "Of an enclosure, for a stated frequency or frequency band, time that would be required for the level of the time-mean-square sound pressure in the enclosure to decrease by 60 dB, after the source has been stopped. Unit, second (s); symbol T60.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Room acoustics", "topic": "Reverberation time (RT60) definition", "applies_to_country": "*", "applies_to_scope": "RT60 is frequency-dependent by definition; a single-number 'RT60' for a room is always a summary.", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_acoustics_flutter_echo", "category": "Studio", "title": "Room acoustics: Flutter echo", "summary": "Flutter echo is a rapid but nearly even succession of echoes from a single sound source, caused by reflection between parallel or nearly parallel surfaces.", "body": "Flutter echo is a rapid but nearly even succession of echoes from a single sound source, caused by reflection between parallel or nearly parallel surfaces.\n\nWhat Acoustical Society of America (ASA/ANSI Acoustical & Bioacoustical Terminology Database) actually says:\n\n“Rapid but nearly even succession of echoes originating from the same sound source when the sound is reflected between parallel or nearly parallel surfaces.”", "source_type": "official", "source_link": "https://asastandards.org/terms/flutter-echo/", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "Acoustical Society of America (ASA/ANSI Acoustical & Bioacoustical Terminology Database)", "evidence_quote": "Rapid but nearly even succession of echoes originating from the same sound source when the sound is reflected between parallel or nearly parallel surfaces.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Room acoustics", "topic": "Flutter echo", "applies_to_country": "*", "applies_to_scope": "Domestic rooms are boxes: two pairs of parallel walls plus floor and ceiling. This is why a bare spare room produces flu", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_acoustics_absorption_coefficient", "category": "Studio", "title": "Room acoustics: Sound absorption coefficient", "summary": "The sound absorption coefficient is the ratio of the Sabine absorption of a surface to the area of that surface.", "body": "The sound absorption coefficient is the ratio of the Sabine absorption of a surface to the area of that surface.\n\nWhat Acoustical Society of America (ASA/ANSI Acoustical & Bioacoustical Terminology Database) actually says:\n\n“Ratio of Sabine absorption of a surface to the area of the surface. Unit, metric sabin per square meter.”\n\nNote: Pair with the transmission loss record below: the two quantities have different definitions, different units and different subjects, which is the formal basis for saying absorption and soundproofing are not the same thing.", "source_type": "official", "source_link": "https://asastandards.org/terms/sound-absorption-coefficient/", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "Acoustical Society of America (ASA/ANSI Acoustical & Bioacoustical Terminology Database)", "evidence_quote": "Ratio of Sabine absorption of a surface to the area of the surface. Unit, metric sabin per square meter.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Room acoustics", "topic": "Sound absorption coefficient", "applies_to_country": "*", "applies_to_scope": "Absorption is a property of a surface facing into a room. It describes energy lost at that surface, not energy stopped f", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_acoustics_transmission_loss", "category": "Studio", "title": "Room acoustics: Sound transmission loss (the soundproofing quantity)", "summary": "Transmission loss of a partition is the difference in decibels between average sound pressure levels in the reverberant source and receiving rooms, adjusted for partition area and receiving-room absorption.", "body": "Transmission loss of a partition is the difference in decibels between average sound pressure levels in the reverberant source and receiving rooms, adjusted for partition area and receiving-room absorption.\n\nWhat Acoustical Society of America (ASA/ANSI Acoustical & Bioacoustical Terminology Database) actually says:\n\n“Of a partition, for a specified frequency or frequency band, difference in decibels between the average sound pressure levels in the reverberant source and receiving rooms, plus ten times the logarithm to the base ten of the ratio of the area of the common partition to the total Sabine absorption in the receiving room.”\n\nNote: The same entry gives a general definition at 5.35: \"Reduction in magnitude of some characteristic of a signal between two stated points in a transmission system.\"", "source_type": "official", "source_link": "https://asastandards.org/terms/transmission-loss/", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "Acoustical Society of America (ASA/ANSI Acoustical & Bioacoustical Terminology Database)", "evidence_quote": "Of a partition, for a specified frequency or frequency band, difference in decibels between the average sound pressure levels in the reverberant source and receiving rooms, plus ten times the logarithm to the base ten of the ratio of the area of the common partition to the total Sabine absorption in the receiving room.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Room acoustics", "topic": "Sound transmission loss (the soundproofing quantity)", "applies_to_country": "*", "applies_to_scope": "This is the quantity that describes soundproofing: it is measured between two rooms across a partition. Absorption coeff", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_acoustics_absorption_vs_soundproofing", "category": "Studio", "title": "Room acoustics: Absorption/treatment is not soundproofing", "summary": "Sound entering or leaving a room is a soundproofing problem, whereas speech clarity, echo or a noisy-sounding environment is a sound treatment problem, and the two need different products.", "body": "Sound entering or leaving a room is a soundproofing problem, whereas speech clarity, echo or a noisy-sounding environment is a sound treatment problem, and the two need different products.\n\nWhat Primacoustic actually says:\n\n“If your main concern is with loud sounds entering or leaving a room that you don't want to hear, then you're dealing with a soundproofing issue. On the other hand, if your issue is with speech clarity, echo, or a noisy environment, then you're likely dealing with a sound treatment problem.”\n\nNote: Tiered B rather than A because Primacoustic sells acoustic treatment and this page is commercial content, not a specification or standard. The formal basis for the same distinction is in the two ASA definitions above (absorption coefficient vs transmission loss), which are tier A.", "source_type": "research", "source_link": "https://www.primacoustic.com/resources/soundproofing-vs-sound-absorption/", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "B", "source_publisher": "Primacoustic", "evidence_quote": "If your main concern is with loud sounds entering or leaving a room that you don't want to hear, then you're dealing with a soundproofing issue. On the other hand, if your issue is with speech clarity, echo, or a noisy environment, then you're likely dealing with a sound treatment problem.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Room acoustics", "topic": "Absorption/treatment is not soundproofing", "applies_to_country": "*", "applies_to_scope": "This is the distinction most often collapsed by consumer advice. Foam panels on a wall change how the room sounds; they ", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_noise_classroom_background_limit", "category": "Studio", "title": "ANSI/ASA S12.60 background noise and reverberation limits", "summary": "ANSI/ASA S12.60 limits the one-hour average background noise level in an unoccupied classroom to 35 dB A-weighted, with maximum reverberation time of 0.6 seconds for rooms under 10,000 cubic feet.", "body": "ANSI/ASA S12.60 limits the one-hour average background noise level in an unoccupied classroom to 35 dB A-weighted, with maximum reverberation time of 0.6 seconds for rooms under 10,000 cubic feet.\n\nWhat Larson Davis (PCB Piezotronics) actually says:\n\n“The ANSI S12.60 limit for the one-hour average of background noise level is 35 dB A-weighted”\n\nNote: Tier B: this is a second-hand report of ANSI/ASA S12.60, which is itself paywalled and was not opened. The RT60 figures come from the same page's summary table and carry the same caveat. Treat the exact numbers as needing confirmation against the standard before being quoted as authoritative.", "source_type": "research", "source_link": "https://www.larsondavis.com/learn/building-acoustics/ansi-standards-for-classroom-acoustics", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "B", "source_publisher": "Larson Davis (PCB Piezotronics)", "evidence_quote": "The ANSI S12.60 limit for the one-hour average of background noise level is 35 dB A-weighted", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Noise floor", "topic": "ANSI/ASA S12.60 background noise and reverberation limits", "applies_to_country": "US", "applies_to_scope": "A classroom standard, not a recording standard. Cited as a documented benchmark for what 'quiet enough for speech' means", "tags": { "lane": "any", "stage": "any", "region": [ "us" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_noise_reverberation_is_noise", "category": "Studio", "title": "Room acoustics: Reverberation degrades intelligibility", "summary": "DPA states that reverberation counts as noise for speech intelligibility purposes, and that intelligibility drops as soon as consonants are smeared out.", "body": "DPA states that reverberation counts as noise for speech intelligibility purposes, and that intelligibility drops as soon as consonants are smeared out.\n\nWhat DPA Microphones actually says:\n\n“Reverberation is considered noise when talking about speech intelligibility. A little reverb may support the speech, however as soon as the consonants are smeared out, intelligibility drops.”", "source_type": "official", "source_link": "https://www.dpamicrophones.com/mic-university/background-knowledge/facts-about-speech-intelligibility/", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "DPA Microphones", "evidence_quote": "Reverberation is considered noise when talking about speech intelligibility. A little reverb may support the speech, however as soon as the consonants are smeared out, intelligibility drops.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Room acoustics", "topic": "Reverberation degrades intelligibility", "applies_to_country": "*", "applies_to_scope": "Explains why a room can measure a low dB noise floor and still sound bad: the interference is the speaker's own sound ar", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_noise_mains_hum_uk", "category": "Studio", "title": "Noise floor: UK mains frequency", "summary": "The UK electricity grid alternates at 50 hertz, and the system operator is required to keep frequency within 0.5 Hz of 50 Hz.", "body": "The UK electricity grid alternates at 50 hertz, and the system operator is required to keep frequency within 0.5 Hz of 50 Hz.\n\nWhat National Energy System Operator (NESO) actually says:\n\n“In the UK, alternating current oscillates 50 times every second, meaning our frequency is 50 hertz (50Hz).”\n\nNote: The page also states: \"We're required to routinely keep the frequency within one percent (0.5Hz) of 50Hz\" and \"we set ourselves a tighter operational target than required, and aim to maintain frequency within 0.2Hz of 50Hz in normal conditions.\"", "source_type": "official", "source_link": "https://www.neso.energy/energy-101/electricity-explained/how-do-we-balance-grid/what-frequency", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "National Energy System Operator (NESO)", "evidence_quote": "In the UK, alternating current oscillates 50 times every second, meaning our frequency is 50 hertz (50Hz).", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Noise floor", "topic": "UK mains frequency", "applies_to_country": "GB", "applies_to_scope": "Mains hum picked up in a UK recording therefore has a fundamental at 50 Hz with harmonics at 100 Hz, 150 Hz and so on. A", "tags": { "lane": "any", "stage": "any", "region": [ "uk" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_noise_mains_hum_us", "category": "Studio", "title": "Noise floor: US mains frequency", "summary": "Interconnected electric systems in North America are designed to operate within a narrow band around 60 hertz.", "body": "Interconnected electric systems in North America are designed to operate within a narrow band around 60 hertz.\n\nWhat U.S. Energy Information Administration (EIA) actually says:\n\n“Interconnected electric systems in North America are designed to operate within a very narrow frequency band around 60 cycles per second (hertz).”\n\nNote: Older page (2011) but the nominal frequency is not a volatile figure.", "source_type": "official", "source_link": "https://www.eia.gov/todayinenergy/detail.php?id=3990", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "U.S. Energy Information Administration (EIA)", "evidence_quote": "Interconnected electric systems in North America are designed to operate within a very narrow frequency band around 60 cycles per second (hertz).", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Noise floor", "topic": "US mains frequency", "applies_to_country": "US", "applies_to_scope": "Mains hum in a US recording has a fundamental at 60 Hz with harmonics at 120 Hz, 180 Hz and so on. The correct notch fre", "tags": { "lane": "any", "stage": "any", "region": [ "us" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_levels_clipping_zero_dbfs", "category": "Studio", "title": "[Unverified - being checked] Recording levels: Clipping at digital full scale", "summary": "[Unverified - being checked] Zoom's H4n Pro manual defines clipping as the input level reaching the maximum the recorder can record, 0 dB, at which point the recorded sound could be distorted.", "body": "Zoom's H4n Pro manual defines clipping as the input level reaching the maximum the recorder can record, 0 dB, at which point the recorded sound could be distorted.\n\nWhat Zoom Corporation actually says:\n\n“What is clipping? If the input level reaches the maximum that the H4n Pro can record (0 dB), the recorded sound could be distorted. The recording level should be adjusted.”\n\nNote: The manual gives no recommended peak target and no statement that clipping is unrecoverable — see could_not_verify. It also states that clip indicators \"light if the recording or playback level reaches 0 dB and remain lit until the file ends or the stop button is pressed\", i.e. the recorder latches the warning.", "source_type": "official", "source_link": "https://zoomcorp.com/media/documents/E_H4n_Pro_REV3.pdf", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Zoom Corporation", "evidence_quote": "What is clipping? If the input level reaches the maximum that the H4n Pro can record (0 dB), the recorded sound could be distorted. The recording level should be adjusted.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Recording levels", "topic": "Clipping at digital full scale", "applies_to_country": "*", "applies_to_scope": "0 dBFS is a hard ceiling in fixed-point digital audio: there is no value above it to record, so the waveform is truncate", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" }, "verification": { "status": "unverified", "label": "Unverified - being checked", "reasons": [ "legal_fetch_over_cap" ], "checked_utc": "20261021-123916Z" } }, { "id": "learn_r27_audio_for_video_wind_foam_attenuation", "category": "Studio", "title": "Foam windshield and furry windjammer performance", "summary": "Rycote states that its microphone foams offer up to 20 dB of wind noise attenuation while keeping high frequency loss to a minimum, and are designed to protect against light wind and pop noise.", "body": "Rycote states that its microphone foams offer up to 20 dB of wind noise attenuation while keeping high frequency loss to a minimum, and are designed to protect against light wind and pop noise.\n\nWhat Rycote actually says:\n\n“Offer up to 20 dB wind noise attenuation, whilst keeping high frequency loss to a minimum.”\n\nNote: Confidence medium: 'up to' with no stated wind speed, measurement method or standard. The page also states foams are \"Designed to protect the microphone head against light wind and pop noise.\" — so a foam does address plosives as well as wind, though less effectively than a dedicated pop filter. On the same page the furry cover is quantified as an addition to the foam, not an alternative to it: \"Providing an additional 12 dB wind-noise attenuation\" in high-wind situations. Both figures are manufacturer claims without stated test conditions. Wind protection is largely irrelevant indoors, where plosives rather than wind are the problem.", "source_type": "official", "source_link": "https://rycote.com/microphone-windshield-shock-mount/mic-foams-and-windjammers/", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Rycote", "evidence_quote": "Offer up to 20 dB wind noise attenuation, whilst keeping high frequency loss to a minimum.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Wind and plosives", "topic": "Foam windshield and furry windjammer performance", "applies_to_country": "*", "applies_to_scope": "Manufacturer figure for its own product range; conditions of measurement are not stated on the page.", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_wind_windscreen_vs_popfilter", "category": "Studio", "title": "Wind and plosives: Windscreen versus pop filter", "summary": "A windscreen is foam that fits snugly over the microphone element casing, whereas a pop filter is acoustically transparent foam and/or mesh placed in front of the microphone element.", "body": "A windscreen is foam that fits snugly over the microphone element casing, whereas a pop filter is acoustically transparent foam and/or mesh placed in front of the microphone element.\n\nWhat Audio-Technica actually says:\n\n“Pop filters usually consist of acoustically transparent foam and/or mesh and work by being placed in front of the microphone element.”\n\nNote: The windscreen half reads: \"Windscreens are usually made from a foam material and are designed to fit snugly over the microphone element casing.\" The page refers to \"excessive plosives such as 'p's' and 'b's'\" but does not define plosives.", "source_type": "official", "source_link": "https://www.audio-technica.com/en-us/support/audio-solutions-question-of-the-week-what-is-the-difference-between-a-windscreen-and-a-pop-filter", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Audio-Technica", "evidence_quote": "Pop filters usually consist of acoustically transparent foam and/or mesh and work by being placed in front of the microphone element.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Wind and plosives", "topic": "Windscreen versus pop filter", "applies_to_country": "*", "applies_to_scope": "The physical difference is contact versus separation: the pop filter puts distance between mouth blast and diaphragm, th", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_wind_plosive_definition", "category": "Studio", "title": "Wind and plosives: What a plosive is", "summary": "Plosives are speech sounds created by releasing a small blast of air, which is what a pop filter is designed to intercept.", "body": "Plosives are speech sounds created by releasing a small blast of air, which is what a pop filter is designed to intercept.\n\nWhat Neumann actually says:\n\n“Linguists call such speech sounds 'plosives', because we create them by releasing a small blast of air.”\n\nNote: The same page describes construction: \"Pop screens, also called pop filters are a dedicated means of protection against such 'pops'. They usually consist of a ring holding two layers of thin fabric.\"", "source_type": "official", "source_link": "https://www.neumann.com/en-us/knowledge-base/neumann-im-homestudio/homestudio-academy/how-to-protect-your-microphone-against-pops", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Neumann", "evidence_quote": "Linguists call such speech sounds 'plosives', because we create them by releasing a small blast of air.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Wind and plosives", "topic": "What a plosive is", "applies_to_country": "*", "applies_to_scope": "Explains why the problem is airflow, not loudness: the diaphragm is being pushed by a puff of air, not overloaded by sou", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_wireless_us_unlicensed_bands", "category": "Studio", "title": "US unlicensed wireless microphone bands", "summary": "In the US, unlicensed wireless microphone use is permitted on the 902-928 MHz band, the 1920-1930 MHz band, and on portions of the 2.4 GHz and 5 GHz bands.", "body": "In the US, unlicensed wireless microphone use is permitted on the 902-928 MHz band, the 1920-1930 MHz band, and on portions of the 2.4 GHz and 5 GHz bands.\n\nWhat Federal Communications Commission (FCC) actually says:\n\n“Unlicensed wireless microphone use is permitted on the 902-928 MHz band, the 1920-1930 MHz, and on portions of the 2.4 GHz and 5 GHz bands”\n\nNote: Retrieved from the FCC's own PDF of the consumer guide; the HTML version at fcc.gov/consumers/guides/operation-wireless-microphones returned HTTP 403 to the fetch tool.", "source_type": "official", "source_link": "https://www.fcc.gov/sites/default/files/operation_of_wireless_microphones.pdf", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "Federal Communications Commission (FCC)", "evidence_quote": "Unlicensed wireless microphone use is permitted on the 902-928 MHz band, the 1920-1930 MHz, and on portions of the 2.4 GHz and 5 GHz bands", "volatility": "medium", "from_batch": "27-audio-for-video", "subject": "Wireless microphones", "topic": "US unlicensed wireless microphone bands", "applies_to_country": "US", "applies_to_scope": "These are the bands a solo creator's consumer wireless kit will normally sit in. Consumer 2.4 GHz systems share spectrum", "tags": { "lane": "any", "stage": "any", "region": [ "us" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_wireless_us_licence_eligibility", "category": "Studio", "title": "Who can be licensed for wireless microphones in the US", "summary": "In the US only specified entities can obtain a wireless microphone licence, including broadcast licensees, broadcast networks, cable operators, and venue operators or sound companies routinely operating 50 or more wireless mics.", "body": "In the US only specified entities can obtain a wireless microphone licence, including broadcast licensees, broadcast networks, cable operators, and venue operators or sound companies routinely operating 50 or more wireless mics.\n\nWhat Federal Communications Commission (FCC) actually says:\n\n“certain specified entities can obtain a license to operate under specified rules and interference protections. Such entities include licensees of AM, FM or TV stations, broadcast networks and cable-television system operators”\n\nNote: The 50-mic category appears separately on the page as \"venue owners/operators and professional sound companies that routinely operate 50 or more wireless mics for events and productions at large venues\".", "source_type": "official", "source_link": "https://www.fcc.gov/sites/default/files/operation_of_wireless_microphones.pdf", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "Federal Communications Commission (FCC)", "evidence_quote": "certain specified entities can obtain a license to operate under specified rules and interference protections. Such entities include licensees of AM, FM or TV stations, broadcast networks and cable-television system operators", "volatility": "medium", "from_batch": "27-audio-for-video", "subject": "Wireless microphones", "topic": "Who can be licensed for wireless microphones in the US", "applies_to_country": "US", "applies_to_scope": "An individual creator filming alone is not eligible for a licence and must therefore operate under the unlicensed rules.", "tags": { "lane": "any", "stage": "any", "region": [ "us" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_wireless_us_prohibited_bands", "category": "Studio", "title": "Wireless microphones: US 600 MHz and 700 MHz prohibition", "summary": "The FCC prohibited use of wireless microphones on unused broadcast channels in the 600 MHz service band and on the 700 MHz band, specifically 698 to 806 MHz.", "body": "The FCC prohibited use of wireless microphones on unused broadcast channels in the 600 MHz service band and on the 700 MHz band, specifically 698 to 806 MHz.\n\nWhat Federal Communications Commission (FCC) actually says:\n\n“the FCC prohibited the use of wireless mics and devices on unused broadcast channels on the 600 MHz service band and on the 700 MHz band – specifically the frequencies between 698 and 806 MHz”", "source_type": "official", "source_link": "https://www.fcc.gov/sites/default/files/operation_of_wireless_microphones.pdf", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "Federal Communications Commission (FCC)", "evidence_quote": "the FCC prohibited the use of wireless mics and devices on unused broadcast channels on the 600 MHz service band and on the 700 MHz band – specifically the frequencies between 698 and 806 MHz", "volatility": "medium", "from_batch": "27-audio-for-video", "subject": "Wireless microphones", "topic": "US 600 MHz and 700 MHz prohibition", "applies_to_country": "US", "applies_to_scope": "Older UHF wireless kit bought before the repack, or imported second-hand, may tune to bands it is now illegal to transmi", "tags": { "lane": "any", "stage": "any", "region": [ "us" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_wireless_uk_licence_exempt", "category": "Studio", "title": "UK licence-exempt wireless microphone bands", "summary": "In the UK, the ranges 173.8-175 MHz, 863-865 MHz and 2400-2483.5 MHz can be used for wireless microphones without a licence.", "body": "In the UK, the ranges 173.8-175 MHz, 863-865 MHz and 2400-2483.5 MHz can be used for wireless microphones without a licence.\n\nWhat Ofcom actually says:\n\n“The ranges 173.8 - 175 MHz and 863 - 865 MHz and 2400 - 2483.5 MHz can be used without a Licence”\n\nNote: The page separately describes two licensed routes: a \"UK wireless microphone licence\" for UHF shared frequencies usable nationwide, and \"Co-ordinated frequencies\" licensed at specific sites.", "source_type": "official", "source_link": "https://www.ofcom.org.uk/spectrum/radio-equipment/mics-monitors", "last_verified": "2026-08-29", "reliability": "VERIFIED RULE", "source_tier": "A", "source_publisher": "Ofcom", "evidence_quote": "The ranges 173.8 - 175 MHz and 863 - 865 MHz and 2400 - 2483.5 MHz can be used without a Licence", "volatility": "medium", "from_batch": "27-audio-for-video", "subject": "Wireless microphones", "topic": "UK licence-exempt wireless microphone bands", "applies_to_country": "GB", "applies_to_scope": "Ofcom also offers a UK wireless microphone licence for shared UHF frequencies usable nationwide, and site-specific co-or", "tags": { "lane": "any", "stage": "any", "region": [ "uk" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_wireless_dropout_causes", "category": "Studio", "title": "Causes of wireless dropouts", "summary": "Shure states that wireless microphone dropouts are most commonly caused by RF interference, antenna issues, frequency conflicts, or faulty system components.", "body": "Shure states that wireless microphone dropouts are most commonly caused by RF interference, antenna issues, frequency conflicts, or faulty system components.\n\nWhat Shure actually says:\n\n“Wireless microphone dropouts are most commonly caused by RF interference, antenna issues, frequency conflicts, or faulty system components.”\n\nNote: The page also states: \"Proper antenna distribution and placement will help to avoid objects such as wireless receivers (RF), rack hardware (metal), and people (water) - all of which can reflect the RF signal causing dropouts.\" It did not use the word multipath, and did not list battery state as a cause.", "source_type": "official", "source_link": "https://www.shure.com/en-US/insights/troubleshooting-wireless-dropouts-10-simple-steps", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Shure", "evidence_quote": "Wireless microphone dropouts are most commonly caused by RF interference, antenna issues, frequency conflicts, or faulty system components.", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Wireless microphones", "topic": "Causes of wireless dropouts", "applies_to_country": "*", "applies_to_scope": "Note that people are listed as RF reflectors: a body between transmitter and receiver is a real cause of dropout, which ", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" } }, { "id": "learn_r27_audio_for_video_sync_timecode_oscillator_drift", "category": "Studio", "title": "[Unverified - being checked] Sync: Clock accuracy and drift in dual-system recording", "summary": "[Unverified - being checked] The Sound Devices MixPre-10T timecode oscillator is specified at 0.1 ppm accuracy, equivalent to 0.25 frame of drift in 24 hours.", "body": "The Sound Devices MixPre-10T timecode oscillator is specified at 0.1 ppm accuracy, equivalent to 0.25 frame of drift in 24 hours.\n\nWhat Sound Devices actually says:\n\n“Accurracy: 0.1 ppm (0.25 frame in 24 hr)”\n\nNote: Quote reproduced with the manual's own typo (\"Accurracy\"). The MixPre-3 and MixPre-6 in the same guide carry no stated ppm accuracy. Do not generalise this figure to phones or consumer cameras — see could_not_verify.", "source_type": "official", "source_link": "https://cdn.sounddevices.com/wp-content/uploads/2022/05/MixPre-I-User-Guide_050622.pdf", "last_verified": "2026-08-29", "reliability": "STRONG PRACTICE", "source_tier": "A", "source_publisher": "Sound Devices", "evidence_quote": "Accurracy: 0.1 ppm (0.25 frame in 24 hr)", "volatility": "low", "from_batch": "27-audio-for-video", "subject": "Sync", "topic": "Clock accuracy and drift in dual-system recording", "applies_to_country": "*", "applies_to_scope": "This is a professional timecode-grade oscillator and is the good case, not the general case. Phones and consumer cameras", "tags": { "lane": "any", "stage": "any", "region": [ "any" ], "platform": "any", "topic": [ "unclassified" ], "explicitness": "any" }, "verification": { "status": "unverified", "label": "Unverified - being checked", "reasons": [ "legal_fetch_over_cap" ], "checked_utc": "20261021-123916Z" } } ] }