Spatial audio psychoacoustics

Sound source localization

Try the Interaural Time Differences example

ILD - Amplitude and spectral cues

Listening Experiment

Experiment 2

Find an environment with a fairly steady high frequency component in the soundscape, e.g. a hiss or broadband sound from a motor or fan, or perhaps a light that is buzzing. Move your head around and you will easily hear the high frequencies getting louder and quieter in each ear. Note that something similar will not and cannot happen for low frequencies.

low frequencies are localized by ITD (interaural time differences)

high frequencies are localized by IAD (interaural amplitude differences)

Localization with only ITD, interaural time differences. Source: IPO73
The same effect in smaller steps with percussive sounds
Switching interaural phase differences of 45° for 500 Hz and 2 kHz tones. Source: IPO72

Listening Experiment - same sound different HRTFS

source: http://recherche.ircam.fr/equipes/salles/listen/sounds.html

PHRTF - Dolby Professional

Cocktail party effect

Same voice with mixed texts, mono then stereo
Two texts, one at a time, then mixed; source: Duda

Distance and depth perception

Distance perception

Quieter (extra distance traveled).
Less high-frequency content (air absorption).
More reverberant (in a reflective environment).
There is less difference between time of direct sound and first-floor reflection.
Attenuated ground reflection.

Apparent source width

Envelopment and spaciousness

Source - DALL-E

How enveloping or spacious is the listener’s perceived environment? This is hard to pin down.

Spaciousness refers to the perceived size of the acoustic space in which the sound is heard. Spaciousness is often used to describe the sense of open space or ‘room’ in which the subject is located, usually due to some sound sources such as musical instruments playing in that space. It is also related to the sense of ‘externalisation’ perceived – whether the sound appears outside the head rather than constrained to a region close to or inside it.

Envelopment refers to the degree to which the sound field surrounds the listener and provides a sense of being enveloped by sound. Envelopment is a similar term used to describe the sense of immersivity and involvement in a (reverberant) soundfield, with that sound coming from all around. It is regarded as a positive quality that is experienced in good concert halls.