les bandes sons sont-elles isosoniques ?

» 12 Déc 2011 12:44

ok, un petit texte qui dit la même chose :

The acoustic realm is where sound actually occurs. Conversational voice level is approximately 65 dB Sound Pressure Level (SPL). Orchestral music in a concert hall ranges from about 50 dB SPL to 120 dB SPL, rock ‘n roll in a club from 80 to 125 dB SPL. Sound becomes really unpleasant for humans above 120 dB SPL, and air begins to distort above about 130 dB SPL. Low level noise floors hover around 50 dB SPL (I’m not going to discuss the meaning of A-weighting here) in our noisy modern world. Interestingly, that acoustical noise floor is not white, like electrical noise, but instead steeply biased toward low frequencies, so we can expect the acoustical noise floor level to be 30 dB louder at 30 Hz. than it will be at 3000 Hz.

More importantly, thanks to the way our hearing works, our perceived frequency response in the acoustical realm varies significantly as a function of loudness (the Fletcher-Munson or Equal Loudness Curves). The perceived loudness of 30 Hz. will probably be 40 dB less, relative to 1 kHz., at 40 dB SPL than it is at 100 dB SPL. That’s a big difference!

Finally, there is no fixed correspondence between electrical signal levels and acoustic sound pressure levels. However, in the film industry, such a level has (roughly) been established so that the electrical signal level 0 VU (usually the same as -20 dBFS in the digital realm) yields 85 dB SPL at the listener’s position for EACH loudspeaker. Meanwhile, in the television world, Dolby’s Dialogue Normalization (AKA “dialnorm”) is intended to calibrate the dialog level of video programs on the entirely reasonable assumption that viewer/listeners will intuitively set that dialog level, which is at –31 dBFS in a “good” stereo television set viewing a correctly calibrated program, to 65 dB SPL.

et beaucoup mieux puisque plus poussé et en français - merci Anaïs !

http://www.cst.fr/IMG/pdf/Sensibilisati ... 019_-1.pdf

» 13 Déc 2011 3:45

la RT019 est en version 3 (application au 1er janvier 2012) avec une valeur de loudness de - 23 LUFS.... on s'éloigne donc du "standard" cinéma à - 31 LKFS.... Le doc d'Anaïs est un poil ancien maintenant (Dolby a été complètement sortit du texte... mais il est vrai qu'Anaïs est consultante Dolby...

)

On se retrouve néanmoins avec le même niveau SPL : 74 dB pour la RT019 (@ -23 LUFS) et l'approche cinéma (@ - 31 LKFS)....

» 13 Déc 2011 11:37

TMS a écrit: Le doc d'Anaïs est un poil ancien maintenant (Dolby a été complètement sortit du texte... mais il est vrai qu'Anaïs est consultante Dolby... )

oui, 2009: un poil ancien, ça change vite dans ce domaine aussi...

Anaïs bosse chez Dolby, et son mémoire (de 2006 !!! une antiquité

) est très interessant:
http://www.ens-louis-lumiere.fr/fileadm ... 06-mem.pdf