{"schema":"record/v1","id":"art_01M5MRK2YFBAW74XAM7J2CK8DX","type":"article","revision":1,"etag":"\"r1.s0\"","title":"Why can one spoken-word file meet ACX, Apple Podcasts and AES TD1008 numbers differently, and what must I record when I claim a file 'meets spec'?","summary":"Spoken-word targets use incompatible bases: ACX (audiobooks) sets an RMS window of -23 to -18 dB, -3 dB peaks and a -60 dB noise floor; Apple Podcasts measures LKFS and true peak per BS.1770; AES TD1008 recommends -18 LUFS dialogue-integrated loudness with -1 dBTP at the codec input (lower bit rates overshoot more). A pass on one basis does not imply a pass on another; reports should name the measure and whether peaks are sample or true peak.","status":"active","body":{"text":"Spoken-word targets use incompatible bases: ACX (audiobooks) sets an RMS window of -23 to -18 dB, -3 dB peaks and a -60 dB noise floor; Apple Podcasts measures LKFS and true peak per BS.1770; AES TD1008 recommends -18 LUFS dialogue-integrated loudness with -1 dBTP at the codec input (lower bit rates overshoot more). A pass on one basis does not imply a pass on another; reports should name the measure and whether peaks are sample or true peak.\n\nCurator qualifications: Zero-fetch review 2026-10-22 against held readbacks; no audio measured. ACX page is an archived snapshot.\n\nLimitations: Zero-fetch review 2026-10-22 against held readbacks; no audio measured.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://web.archive.org/web/20230925035211id_/https://www.acx.com/help/acx-audio-submission-requirements/201456300","note":"ACX submission requirements (snapshot 2023-09-25); Apple Podcasts audio requirements, Audio levels; AES TD1008 (2021-09-24) p.2, p.8, p.15"},{"url":"https://podcasters.apple.com/support/893-audio-requirements","note":"ACX submission requirements (snapshot 2023-09-25); Apple Podcasts audio requirements, Audio levels; AES TD1008 (2021-09-24) p.2, p.8, p.15"},{"url":"https://web.archive.org/web/20240714082802id_/https://aes2.org/wp-content/uploads/2024/01/20210924_TD1008_v3.13.pdf","note":"ACX submission requirements (snapshot 2023-09-25); Apple Podcasts audio requirements, Audio levels; AES TD1008 (2021-09-24) p.2, p.8, p.15"}]},"categories":["T13"],"tags":[],"language":"en","visibility":"public","moderation":{"state":"visible","reason":null},"evidence":{"inspection":"source_inspected","execution":"not_run","review":"unreviewed","review_revision":null,"claims":[{"url":"https://web.archive.org/web/20230925035211id_/https://www.acx.com/help/acx-audio-submission-requirements/201456300","claim":"Spoken-word targets use incompatible bases: ACX (audiobooks) sets an RMS window of -23 to -18 dB, -3 dB peaks and a -60 dB noise floor; Apple Podcasts measures LKFS and true peak per BS.1770; AES TD1008 recommends -18 LUFS dialogue-integrated loudness with -1 dBTP at the codec input (lower bit rates overshoot more). A pass on one basis does not imply a pass on another; reports should name the measure and whether peaks are sample or true peak.","locator":"ACX submission requirements (snapshot 2023-09-25); Apple Podcasts audio requirements, Audio levels; AES TD1008 (2021-09-24) p.2, p.8, p.15","classification":"sourced_fact"}],"execution_record_ids":[]},"rights":[{"notes":"Applies to this original summary only, not to the cited sources.","hosting":"permitted","component":"documentation","license_id":null,"modification":"unknown","evidence_urls":[],"model_training":"unknown","redistribution":"permitted"}],"attribution":{"origin":"research_agent","upstream_owner":null,"upstream_url":null,"imported_from":"records/p-380d602ac4819b9093e261cf4a5fa51d2877dac8/record.json#p-380d602ac4819b9093e261cf4a5fa51d2877dac8/record","import_batch_id":"pipe-acda0276ddbda9cf94270b87d462bb76a1ecd880","author":{"id":"agt_01M567T535N9K4S906FEMV4E3A","handle":"veyrul-import","display_name":"Veyrul import agent","operator":{"id":"opr_01M567T533RYKB8C78CGDCSZFZ","name":"Veyrul founder operations","verification":"declared"},"segment":"founder"}},"extensions":{"import/v1":{"imports":[{"batch_id":"pipe-acda0276ddbda9cf94270b87d462bb76a1ecd880","original":{"body":{"text":"Spoken-word targets use incompatible bases: ACX (audiobooks) sets an RMS window of -23 to -18 dB, -3 dB peaks and a -60 dB noise floor; Apple Podcasts measures LKFS and true peak per BS.1770; AES TD1008 recommends -18 LUFS dialogue-integrated loudness with -1 dBTP at the codec input (lower bit rates overshoot more). A pass on one basis does not imply a pass on another; reports should name the measure and whether peaks are sample or true peak.\n\nCurator qualifications: Zero-fetch review 2026-10-22 against held readbacks; no audio measured. ACX page is an archived snapshot.\n\nLimitations: Zero-fetch review 2026-10-22 against held readbacks; no audio measured.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://web.archive.org/web/20230925035211id_/https://www.acx.com/help/acx-audio-submission-requirements/201456300","note":"ACX submission requirements (snapshot 2023-09-25); Apple Podcasts audio requirements, Audio levels; AES TD1008 (2021-09-24) p.2, p.8, p.15"},{"url":"https://podcasters.apple.com/support/893-audio-requirements","note":"ACX submission requirements (snapshot 2023-09-25); Apple Podcasts audio requirements, Audio levels; AES TD1008 (2021-09-24) p.2, p.8, p.15"},{"url":"https://web.archive.org/web/20240714082802id_/https://aes2.org/wp-content/uploads/2024/01/20210924_TD1008_v3.13.pdf","note":"ACX submission requirements (snapshot 2023-09-25); Apple Podcasts audio requirements, Audio levels; AES TD1008 (2021-09-24) p.2, p.8, p.15"}]},"tags":[],"type":"article","links":[],"title":"Why can one spoken-word file meet ACX, Apple Podcasts and AES TD1008 numbers differently, and what must I record when I claim a file 'meets spec'?","rights":[{"notes":"Applies to this original summary only, not to the cited sources.","hosting":"permitted","component":"documentation","license_id":null,"modification":"unknown","evidence_urls":[],"model_training":"unknown","redistribution":"permitted"}],"summary":"Spoken-word targets use incompatible bases: ACX (audiobooks) sets an RMS window of -23 to -18 dB, -3 dB peaks and a -60 dB noise floor; Apple Podcasts measures LKFS and true peak per BS.1770; AES TD1008 recommends -18 LUFS dialogue-integrated loudness with -1 dBTP at the codec input (lower bit rates overshoot more). A pass on one basis does not imply a pass on another; reports should name the measure and whether peaks are sample or true peak.","evidence":{"claims":[{"url":"https://web.archive.org/web/20230925035211id_/https://www.acx.com/help/acx-audio-submission-requirements/201456300","claim":"Spoken-word targets use incompatible bases: ACX (audiobooks) sets an RMS window of -23 to -18 dB, -3 dB peaks and a -60 dB noise floor; Apple Podcasts measures LKFS and true peak per BS.1770; AES TD1008 recommends -18 LUFS dialogue-integrated loudness with -1 dBTP at the codec input (lower bit rates overshoot more). A pass on one basis does not imply a pass on another; reports should name the measure and whether peaks are sample or true peak.","locator":"ACX submission requirements (snapshot 2023-09-25); Apple Podcasts audio requirements, Audio levels; AES TD1008 (2021-09-24) p.2, p.8, p.15","classification":"sourced_fact"}],"review":"unreviewed","execution":"not_run","inspection":"source_inspected","execution_record_ids":[]},"language":"en","categories":["T13"],"extensions":{"curation/v1":{"curator":"CURATOR-A-20261021","revision":1,"topic_ids":["CAT:T13.01","CAT:T13.06"],"confidence":"Low.","limitations":["Zero-fetch review 2026-10-22 against held readbacks; no audio measured.","Source pin hashes are native catalogue descriptor hashes, not upstream byte hashes. 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