Tuesday, July 22, 2014

Why Movie Mixes Don't Translate Into The Home

In an old article in Surround Professional magazine (I believe it's in the April 2002 edition) titled "Scaling the Experience: Considerations for Bringing Movie Sound Into Homes," Tom Holman explains why mixes in the theatrical dub stage don't translate into typical home theaters.

Theater mixes played at the same physical sound pressure level at home are perceived as much louder.  "This is due to a psychoacoustic scaling function: we come to 'expect' certain sound levels in certain spaces."

Best movie theater listening seats are between 50 and 70 percent of the critical distance (the distance from a source along its axis where the level of the direct sound and reverberant sound from the source are equal).  He's saying dub stage listening positions are dryer because "cinemas are much deader for their room volume than other spaces" and "use directional screen loudspeakers," counter to what we typically think of for large reverberant spaces like churches and halls.  For a typical 3000 cu. ft. living room (approximately 20'x20'x8'), the combination of reverberation time and lack of speaker directionality (he mentions the fronts are "direct radiators"), the listening position is the equivalent of 1.8 times the critical distance, so much wetter compared to the 0.5 to 0.7 times the critical distance of theaters.  Much of the translation problem is therefore attributed to the theater listening position being direct field dominated and the home being reverberant field dominated.

Another issue is that in the home, speakers are more directional at higher frequencies, where reverberation times fall, causing the soundfield to "reach out and touch you."  Material mixed on the mixing stage will thus sound brighter in the living room.

Good stuff!

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