{"schema":"record/v1","id":"art_01M5P23R1E88F2TNKTRMNCPBZN","type":"article","revision":1,"etag":"\"r1.s0\"","title":"What is Leq(m), what does the M in it stand for, and why is it used for trailers and cinema ads rather than A- or C-weighting?","summary":"Problem. Cinema trailers and ads need a loudness number that tracks perceived loudness, and peak or A/C-weighted levels did not. Conditions. Short-duration promotional material with strong upper-mid content; the account is from Dolby's Ioan Allen. Method. Leq(m) is an Leq (long-term average level) with an M-weighting curve, proposed after Dolby research in 1996; the paper says M-weighting, favouring the 2 to 3 kHz region, gave a better loudness 'hierarchy' (ranking of louder/quieter) on trailers and cinema-specific commercials than C-weighting, A-weighting or none. Example. The paper's 'm' stands for 'movies'. Failure modes. A plain long-term Leq on a whole feature misleads (a loud final reel averages low), which is why a rolling window was later proposed in C3-B784-04. Limitations. The M-weighting curve values are in a figure, not the text; the Leq(m) meter/standard documents (ISO 21727, Dolby meter manuals) were not fetched, so the exact filter is not stated here. Version/date. IS...","status":"active","body":{"text":"Problem. Cinema trailers and ads need a loudness number that tracks perceived loudness, and peak or A/C-weighted levels did not. Conditions. Short-duration promotional material with strong upper-mid content; the account is from Dolby's Ioan Allen. Method. Leq(m) is an Leq (long-term average level) with an M-weighting curve, proposed after Dolby research in 1996; the paper says M-weighting, favouring the 2 to 3 kHz region, gave a better loudness 'hierarchy' (ranking of louder/quieter) on trailers and cinema-specific commercials than C-weighting, A-weighting or none. Example. The paper's 'm' stands for 'movies'. Failure modes. A plain long-term Leq on a whole feature misleads (a loud final reel averages low), which is why a rolling window was later proposed in C3-B784-04. Limitations. The M-weighting curve values are in a figure, not the text; the Leq(m) meter/standard documents (ISO 21727, Dolby meter manuals) were not fetched, so the exact filter is not stated here. Version/date. ISDCF-Doc11, 2016-03-15.\n\nCurator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.\n\nLimitations: Author is the originator's employer; the paper reports no sample size for the weighting comparison and shows the curve only in a figure. ISO 21727 text is paywalled and was not read.\n\nEvidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.","citations":[{"url":"https://files.isdcf.com/papers/ISDCF-Doc11-MovieLoudnessMeasurement20160315.pdf","note":"ISDCF-Doc11 p.2 (Leq(m)); ISDCF-Doc11 p.3 (Hierarchy); ISDCF-Doc11 p.4 (references); researcher reasoning"}]},"categories":["T13","T14"],"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://files.isdcf.com/papers/ISDCF-Doc11-MovieLoudnessMeasurement20160315.pdf","claim":"Problem. Cinema trailers and ads need a loudness number that tracks perceived loudness, and peak or A/C-weighted levels did not. Conditions. Short-duration promotional material with strong upper-mid content; the account is from Dolby's Ioan Allen. 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Short-duration promotional material with strong upper-mid content; the account is from Dolby's Ioan Allen. Method. Leq(m) is an Leq (long-term average level) with an M-weighting curve, proposed after Dolby research in 1996; the paper says M-weighting, favouring the 2 to 3 kHz region, gave a better loudness 'hierarchy' (ranking of louder/quieter) on trailers and cinema-specific commercials than C-weighting, A-weighting or none. Example. The paper's 'm' stands for 'movies'. Failure modes. A plain long-term Leq on a whole feature misleads (a loud final reel averages low), which is why a rolling window was later proposed in C3-B784-04. Limitations. The M-weighting curve values are in a figure, not the text; the Leq(m) meter/standard documents (ISO 21727, Dolby meter manuals) were not fetched, so the exact filter is not stated here. Version/date. IS...","evidence":{"claims":[{"url":"https://files.isdcf.com/papers/ISDCF-Doc11-MovieLoudnessMeasurement20160315.pdf","claim":"Problem. 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