Sound Localization - Binaural

n Interaural time difference - 2 parts

q Diff in time of arrival (up to 600 ms) – can detect as small as 10 ms

q Phase difference – good for low pitched tones (<1500 hz) – diff portion of wave hits each ear

n Interaural intensity difference

q Sound falls off with distance

q Portion of energy blocked because of head (sound shadow)

q High pitched tones (> 1000 hz)– up to 20 db diff

Monaural and other factors

n Pinna – features force sound wave to bounce around slightly before entering ear – pattern of delay depends on original location of sound directional transfer function - sounds from side, see decreases around 6K, 11K, and 14K hz, from front, 10K, peak at 13K, from above, note between 8K and 10K.

n Doppler shift – waves pile closer together moving toward you – increase pitch (decrease if move away)

n Usually listening to complex tone

n Move head and body to solve ambiguities

Surround sound home - digital

n Center, 2 front, 2 side, subwoofer (and maybe back)

n Subwoofer

n place anywhere because <100 hz, problems localizing sound

n Other speakers use binaural sound localization (older systems dolby surround - back speakers were mono)

n Need more treble at home than movies because layout of movies (chairs, drapes, size)

n Loudness button amplify lo and hi pitches (at low amp)

Subwoofer

– place anywhere because <100 hz, problems localizing sound best near wall for bass
Center – 50% of soundtrack, most of dialogue
Front – floor has more bass that bookshelf or satellite (so need subwoofer esp if not floor)
Set equidistance pts to rt and lt with center – form arc, tweeters at ear level when seated for best high freq, not too near wall (good bass, not good midrange freq)
Surround/side – side or just behind
Sound should go over head not directly at you