The Hearing Brain
This chapter first considers how sounds are processed by the early auditory system up to the primary and secondary auditory cortex. The hearing brain is concerned with extracting “constancy” out of an infinitely varying array of sensory inputs and actively interprets the sensory input, using stored knowledge of sound structure (e.g., in speech). Similarly to vision, there is evidence of auditory-based ventral routes (involved in processing the meaning of sounds) and dorsal route (involved in locating sounds, and also linking to the motor system). The chapter also considers auditory perception for three different classes of stimuli: music, voices, and speech. Within each of these domains, there may be further specialization of processing. In the example of music perception, there is a broad distinction between pitch versus rhythm processing.
Multiple Choice Questions
Flashcards
Sounds with a sinusoid waveform (when pressure change is plotted against time)
The perceived property of sounds that enables them to be ordered from low to high
The perceived intensity of the sound
The lowest frequency component of a complex sound that determines the perceived pitch
If the fundamental frequency of a complex sound is removed, then the pitch is not perceived to change (the brain reinstates it)
Missing fundamental phenomenon
The perceptual quality of a sound enables us to distinguish between different musical instruments
Part of the inner ear that converts liquid-borne sound into neural impulses
A membrane within the cochlea containing tiny hair cells linked to neural receptors
The main cortical area to receive auditory-based thalamic input
Part of secondary auditory cortex, with many projections from primary auditory cortex
Part of secondary auditory cortex, receiving projections from the adjacent belt region
The principle that sounds close to each other in frequency are represented by neurons that are spatially close to each other in the brain
In fMRI, a short break in scanning to enable sounds to be presented in relative silence
An internal model of how sounds get distorted by the unique shape of one’s own ears and head
Head-related transfer function (HRTF)
A part of auditory cortex (posterior to primary auditory cortex) that integrates auditory information with non-auditory information, for example to enable sounds to be separated in space
The difference in timing between a sound arriving in each ear (used to localize sounds)
Inter-aural time difference
The difference in loudness between a sound arriving in each ear (used to localize sounds)
Inter-aural intensity difference
The problem of attending to a single auditory stream in the presence of competing streams (with different acoustic and spatial properties)—for instance, attending to one person’s voice in a noisy room of other voices
The division of a complex auditory signal into different sources or auditory objects
Auditory stream segregation
An ERP component that occurs when an auditory stimulus deviates from previously presented auditory stimuli
Mismatch negativity (MMN)
An auditory agnosia in which music perception is affected more than the perception of other sounds
A developmental difficulty in perceiving pitch relationships
Tone-deafness (or congenital amusia)
Changes in the stress pattern of speech (e.g. to add emphasis), the rhythm of speech, or the intonation (e.g. rising/falling pitch to indicate questioning or sarcasm)
Patterns of pitch over time
Type of auditory agnosia in which patients are able to identify environmental sounds and music but not speech
This plots the frequency of sound (on the y-axis) over time (on the x-axis) with the intensity of the sound represented by how dark it is
Different spoken/acoustic renditions of the same phoneme
Horizontal stripes on the spectrogram produced with a relative free flow of air (e.g. by vowels)
Vibration of the vocal cords that characterizes the production of some consonants
The production of one phoneme is influenced by the preceding and proceeding phonemes
An auditory perception derived from a fusion of mismatching heard speech and seen speech
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Useful Links
Make your own spectrograms using the free software Audacity (www.audicityteam.org ). Here’s a simple guide: www.pretzellogic.net/2012/03/12/make-a-spectrogram/
