DTS Pro Series Surround Encoder – Installation and User Manual
The purpose of DIALNORM is to achieve a consistent level of dialog from one program or program source to the next. End-users set volume to achieve a pleasing and intelligible level of dialog. However, dialog level varies considerably across different program types. For example, in a feature motion picture, dialog typically averages -27 dBFS LeqA in order to allow sufficient headroom for explosions and other effects. In contrast, in a news broadcast the announcer s voice may average 15 dB, closer to full scale. Various other programs will have other dialog levels appropriate to their headroom needs. If there is no compensation, the end-user will have to turn up the feature film, turn down the news broadcast, etc. With dialog normalization, a DIALNORM value of -27 is assigned to the movie, and a value of -15 is assigned to the newscast. The dialog levels then match on playback and no user adjustment should be necessary.
For music, which contains no dialog, DIALNORM may be used to set playback loudness at a level appropriate in the context of other program material, determined subjectively.
A DIALNORM value of -31 results in no DIALNORM attenuation.
For broadcast or disc authoring of a feature motion picture, if direct measurement has not indicated a different level, set the DIALNORM value to -27. This has been widely accepted as typical for features, and THX-certified playback equipment assumes a value of -27 in aligning levels between the home and the dubbing stage.
If more than one codec is being used for the same audio track (for example, on DVD), DIALNORM value should be set the same on all codecs for a given program.
For further information on DIALNORM, including typical values for different types of programs and music, see:
Tomlinson Holman, 5.1 Surround Sound Up and Running. Boston: Focal Press, 2000. 163-167.
