Ch 10 - Hearing in the Environment

interaural time difference (ITD)

the difference in time between arrivals of sound at one ear versus the other

azimuth

the angle of a sound source on the horizontal plane relative to a point in the center of the head between the ears

medial superior olive (MSO)

a relay station in the brainstem where inputs from both ears contribute to detection of the interaural time difference

interaural level difference (ILD)

the difference between levels (intensities) of sound at one ear versus the other

lateral superior olive (LSO)

a relay station in the brainstem where inputs from both ears contribute to detection of the interaural level difference

cone of confusion

a region of positions in space where all sounds produce the same time and level (intensity) differences (ITDs and ILDs)

directional transfer function (DTF)

a measure that describes how the pinna, ear canal, head, and torso change the intensity of sounds with different frequencies that arrive at each ear from different locations in space

inverse-square law

a principle staring that as distance from a source increases, intensity decreases faster such that decrease in intensity is equal to the distance squared

harmonic spectrum

the spectrum of a complex sound in which energy is at integer multiples of the fundamental frequency

fundamental frequency

the lowest-frequency component of a complex periodic sound

timbre

the psychological sensation by which a listener can judge that two sounds with the same loudness and pitch are dissimilar

quality is conveyed by harmonics and other high frequencies

attack

the part of a sound during which amplitude increases (onset)

decay

the part of a sound during which amplitude decreases (offset)

auditory scene analysis

processing an auditory scene consisting of multiple sound sources into separate sound images

auditory stream segregation

the perceptual organization of a complex acoustic signal into separate auditory events for which each stream is heard as a separate event

similarity

gestalt grouping rule stating that the tendency of two sounds to group together will increase as the acoustic similarity between them increases

common fate

gestalt grouping rule stating that the tendency of sounds to group together will increase if they begin and/or end at the same time

good continuation

gestalt grouping rule stating that sounds will tend to group together as continuous if they seem to share a common path, similar to a shared contour for vision

acoustic startle reflex

the very rapid motor response to a sudden sound

very few neurons are involved in the basic startle reflex, which can also be affected by emotional state

inattentional deafness

the failure to notice a fully-audible, but unexpected sound because attention was engaged on auditory stream