Dialogue Normalization
Dear Gary: Hopefully you guys can answer a question for me. Two DVDs you guys have reviewed,(Charlie’s Angels and Vertical Limit) are said to have a dialnorm of -7, but my Denon AVR-4800 display says -3 on it for both of these DVDs. Is there a reason for this or is it possible my receiver could be defective?
Movie Sound Editor Perry Sun Comments:
Both Charlie’s Angels and Vertical Limit indeed have been encoded with a dialnorm offset of -7 dB. Your Denon AVR-4800, and some other receivers apply a 4 dB increase in overall level with Dolby Digital soundtracks, apparently to compensate for the fact that the majority of DVD movie soundtracks feature a -4 dB offset, which is the default setting of the Dolby Digital encoders (-27 dBFS, or 27 dB below full-scale digital, to be more exact). Therefore, the dialnorm reading you get is 4 dB higher than what it should be. Dolby justifies the -27 dBFS dialnorm setting for movie soundtracks on the basis of the fact that the dialogue normally occurs at around this level (or equivalently 78 dB sound pressure level). However, you need to also calibrate your sound system with test tones that have been encoded with this dialnorm setting (such as with the AVIA Guide To Home Theater DVD), to be sure that output levels are properly reproduced. Of course, another consequence of calibrating in this manner is that DTS soundtracks, which are always encoded and decoded with no overall gain, will be 4 dB too high at the reference level volume setting. And if you elect to use your Denon’s internal test tones for calibration, which like all other THX-certified receivers and surround processors, are referenced to the film sound calibration level, DTS soundtracks play correctly at the reference level setting, but Dolby Digital soundtracks are 4 dB too low. If you have a receiver or surround processor that can defeat the dialnorm offset, these problems will then be avoided. What a confusing world!
You can E-mail Widescreen Review @ mailto:editorgary@widescreenreview.com