Lecture 3 Definitions: Hearing, Music, and Speech

place code (place principle)

the frequency of a sound is coded by the place along the cochlear partition that has the greatest mechanical displacement

temporal code (frequency principle)

the frequency of a sound is coded by the timing of neural firing as it relates to the period of the sound

harmonic spectrum

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

fundamental frequency

lowest frequency of harmonic spectrum

missing fundamental effect

perceived pitch corresponds to the fundamental frequency, even if it is missing

azimuth

the angle of a sound source on the horizon relative to a point in the centre of the head between the ears

interaural time differences (ITD)

the difference in time between a sound arriving at one ear versus the other

interaural level differences (ILD)

the difference in level/intensity between a sound arriving at one ear versus the other

cone of confusion

region of positions in space where all sounds produce the same ITDs and ILDs

directional transfer function

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 (azimuth and elevation)

spectral composition

higher frequencies decrease in energy more than lower frequencies with distance (atmospheric absorption, objects)

tone height

sound quality corresponding to the level of pitch

tone chroma

sound quality shared by tones that have the same octave interval

octave

the interval between two sound frequencies having a ratio of 2:1

source segregation (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

spectrogram

a pattern for sound analysis that provides a three-dimensional display plotting time on the horizontal axis, frequency on the vertical axis, and intensity in colour or gray scale

coarticulation

the influence of one phoneme on the acoustic properties of another, due to the articulatory movements required to produce them in sequence

motor theory of speech perception

motor processes used to produce speech sounds are used in reverse to understand the acoustic speech signal

medial superior olives (MSOs)

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

lateral superior olives (LSOs)

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

inverse-square law

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

attack

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

decay

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

similarity

gestalt grouping rule stating that the tendency of two features to group together will increase as the 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 two elements will tend to group together if they seem to lie on the same contour

acoustic startle reflex

very rapid motor response to a sudden sound

inattentional deafness

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

melody

sequence of sounds perceived as a single coherent structure

syncopation

any deviation from a regular rhythm

vocal folds

pair of elastic tissues that vibrate as a result of airflow generated by lungs, depending on how close or apart and how tense or lax they are

phonation

the process through which vocal folds are made to vibrate when air pushes out of the lungs

vocal tract

airway above the larynx used for the production of speech. vocal tract includes the oral tract and nasal tract

articulation

the act or manner of producing a speech sound using the articulators—vocal tract structures including the mouth, tongue, soft palate, and jaw

categorical perception

phenomenon by which the discrimination of items is no better than the ability to label items