VR Audio Glossary

Definitions of technical terms VR audio terms.



Producing no echoes; very low or no reverberation.


A loss of energy; in acoustics, typically a reduction in volume.

Direct Sound

Sound that has traveled directly to the listener without reflecting (versus reverberant sound).

Early Reflections

Reflected sounds that arrive relatively soon at a listener's location (i.e., before Late Reflections).

Head-Related Impulse Response (HRIR)

A formal characterization of the effect of sound interacting with the geometry of a particular human body. Used to create head-related transfer functions.

Head-Related Transfer Function (HRTF)

A transformation of an acoustic signal using a head-related impulse response. Used to simulate the effects of interaction of a sound originating from a specific direction with the geometry of a particular human body.

Head Shadowing

The attenuation of sound caused by the head lying between an ear and the sound source.

Initial Time Delay

The interval between the arrival of a direct sound and its first reflection.

Interaural Level Difference (ILD)

The difference in a sound's level or volume between the two ears.

Interaural Time Difference (ITD)

The length of the interval between when a sound arrives at the first ear and when it arrives as the second ear.

Late Reflections

Reflected sounds that arrive relatively late at a listener's location (i.e., after early reflections).

Motion Parallax

When moving objects are father from a perceiver, their apparent speed of travel decreases; for example, a moving airplane on the horizon appears to be traveling more slowly than a nearby car. The apparent rate of travel of an object can therefore be used as a distance cue.


The visible portion of the ear that lies outside the head.

Reverberant Sound

Sound that has reflected or reverberated before arriving at a listener's location (versus direct sound).


The reflection of sound off of a surface, or the temporary persistence of sound in a space caused by reverberation.

Sound Localization

1. The process of determining the location of a sound's origin; or 2. the suggestion of an object's location based on the manipulation of auditory cues.

Sound Spatialization

The representation of a sound within three-dimensional space.