Hearing: The Auditory System, Localisation, And Auditory Scene Analysis Flashcards
1
Q
Define
Acoustic shadow
A
an area through which sound waves fail to propagate, due to topographical obstructions or disruption of the waves via phenomena such as wind currents, buildings, or sound barriers
2
Q
Define
Additive synthesis
A
process of adding harmonics to create complex sounds
3
Q
Define
Amplitude
A
the fluctuation or displacement of a wave from its mean value
4
Q
Define
Amplitude modulation
A
the modulation of a wave by varying its amplitude, used especially as a means of broadcasting an audio signal by combining it with a radio carrier wave
5
Q
Define
Amplitude-modulated noise
A
the detection of modulation versus the detection of modulation rate
6
Q
Define
Aperiodic sounds
A
sound whose pattern does not repeat itself as do those of the periodic sounds
7
Q
Define
Attack
A
changes occurring before the sound reaches its steady-state intensity
8
Q
Define
Audibility curve
A
the relationship between the threshold of hearing for a pure tone, expressed in decibels sound-pressure level (dB SPL), and the frequency of the tone
9
Q
Define
Auditory canal
A
canal leading from the opening of the external ear to the eardrum
10
Q
Define
Auditory localisation
A
describes an organism’s ability to perceive the location of the source of a sound
11
Q
Define
Auditory
A
falls between the audibility curve and and the. threshold for feeling
12
Q
Define
Auditory scene analysis
A
a proposed model for the basis of auditory perception. This is understood as the process by which the human auditory system organizes sound into perceptually meaningful elements
13
Q
Define
Auditory space
A
surrounds an observer and exists wherever there is sound
14
Q
Define
Auditory stream segragation
A
the perceptual grouping of sounds, to form coherent representations of objects in the acoustic scene, and is a fundamental aspect of hearing and speech perception
15
Q
Define
Azimuth
A
the direction of a celestial object from the observer, expressed as the angular distance from the north or south point of the horizon to the point at which a vertical circle passing through the object intersects the horizon.
16
Q
Define
Basilar membrane
A
a stiff structural element within the cochlea of the inner ear which separates two liquid-filled tubes that run along the coil of the cochlea, the scala media and the scala tympani.
17
Q
Define
Bass ratio
A
ratio of low to middle frequencies reflected from surfaces
18
Q
Define
Belt area
A
the secondary auditory cortex immediately surrounding the core
19
Q
Define
Binaural cues
A
any difference in the sound arriving at the two ears from a given sound source (interaural difference) that acts as a cue to permit auditory localization
20
Q
Define
Characteristic frequency
A
The frequency of a sound at which the threshold of a single fibre of an auditory nerve is lowest and to which it is therefore most responsive
21
Q
Define
Cilia
A
the mechanosensing organelles of hair cells, which respond to fluid motion in numerous types of animals for various functions, including hearing and balance
22
Q
Define
Cochlea
A
a spiralled, hollow, conical chamber of bone, in which waves propagate from the base (near the middle ear and the oval window) to the apex (the top or center of the spiral)
23
Q
Define
Cochlear amplifier
A
a positive feedback loop within the cochlea that amplifies the traveling wave
24
Q
Define
Cochlear nucleus
A
the obligatory nucleus in which all ascending information from the cochlea forms synaptic connections with the auditory brain
25
# Define
Coincidence detectors
the context of neurobiology is a process by which a neuron or a neural circuit can encode information by detecting the occurrence of temporally close but spatially distributed input signals
26
# Define
Condensation
part of a sound wave where the density is higher than normal
27
# Define
Decay
rate at which the music fades to silence
28
# Define
Direct sound
sound that reaches the listener's ears straight from the source
29
# Define
Effect of the missing fundamental
Removal of the first harmonic in a sound with the same perceived pitch, but with a different timbre
30
# Define
Event related potential
the measured brain response that is the direct result of a specific sensory, cognitive, or motor event
31
# Define
First harmonic
another term for the fundamental frequency which sets the repetition rate
32
# Define
Frequency
the number of occurrences of a repeating event per unit of time
33
# Define
Frequency spectrum
display of harmonics of a complex sound
34
# Define
Fundamental
the lowest frequency of a periodic waveform
35
# Define
Fundamental frequency
the lowest frequency which is produced by the oscillation of the whole of an object, as distinct from the harmonics of higher frequency
36
# Define
Hair cells
the sensory receptors of both the auditory system and the vestibular system in the ears of all vertebrates, and in the lateral line organ of fishes
37
# Define
Harmonic
a signal or wave whose frequency is an integral (whole-number) multiple of the frequency of some reference signal or wave
38
# Define
Hertz (Hz)
the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second
39
# Define
Incus
a bone in the middle ear. The anvil-shaped small bone is one of three ossicles in the middle ear
40
# Define
Indirect sound
sound that is reflected off of environmental surfaces and then to the listener
41
# Define
Inferior colliculus
the principal midbrain nucleus of the auditory pathway and receives input from several peripheral brainstem nuclei in the auditory pathway, as well as inputs from the auditory cortex
42
# Define
Inner hair cells
the sensory cells of the cochlea, are responsible for signal transduction
43
# Define
Interaural level difference (ILD)
the difference in loudness and frequency distribution between the two ears
44
# Define
Interaural time difference (ITD)
the difference in arrival time of a sound between two ears
45
# Define
Intimacy time
time between when sound leaves its source and when the first reflection arrives
46
# Define
Jeffress model
a neurocomputational model that explains how auditory systems can register and analyze small differences in the arrival time of sounds at the two ears in order to estimate the direction of sound sources in the azimuthal plane.
47
# Define
Loudness
the subjective perception of sound pressure
48
# Define
Malleus
a hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum
49
# Define
Medial geniculate nucleus
part of the auditory thalamus and represents the thalamic relay between the inferior colliculus (IC) and the auditory cortex (AC).
50
# Define
Melody
a sequence of single notes that is musically satisfying; a tune.
51
# Define
Middle ear
the portion of the ear internal to the eardrum, and external to the oval window of the inner ear
52
# Define
Middle ear muscles
two muscles which serve a protective function in the middle ear; the tensor tympani and stapedius
53
# Define
Monaural cue
relies on sounds reaching a single ear to constrain the set of possible sound sources
54
# Define
Octave
the interval between one musical pitch and another with double its frequency
55
# Define
Onset time
sounds that start at different times are likely to come from different sources
56
# Define
Organ of Corti
the receptor organ for hearing and is located in the mammalian cochlea. This highly varied strip of epithelial cells allows for transduction of auditory signals into nerve impulses' action potential.
57
# Define
Ossicles
three bones in either middle ear that are among the smallest bones in the human body.
58
# Define
Outer ear
the external portion of the ear, which consists of the auricle (also pinna) and the ear canal
59
# Define
Oval window
a membrane-covered opening that leads from the middle ear to the vestibule of the inner ear
60
# Define
Periodic sounds
sounds which repeats itself at regular intervals
61
# Define
Periodicity pitch
Removal of the first harmonic in a sound with the same perceived pitch, but with a different timbre
62
# Define
Phase locking
the mechanism by which the peripheral auditory system keeps track of the times of occurrence of the ongoing amplitude fluctuations in sounds
63
# Define
Pinnae
the external part of the ear in humans and other mammals; the auricle
64
# Define
Place theory
a theory of hearing that states that our perception of sound depends on where each component frequency produces vibrations along the basilar membrane
65
# Define
Precedence effect
a binaural psychoacoustical effect. When a sound is followed by another sound separated by a sufficiently short time delay (below the listener's echo threshold), listeners perceive a single auditory event
66
# Define
Presbycusis
the loss of hearing that gradually occurs in most individuals as they grow older
67
# Define
Primary auditory cortex (A1)
part of the temporal lobe that processes auditory information in humans and many other vertebrates
68
# Define
Pure tone
a sound with a sinusoidal waveform; that is, a sine wave of any frequency, phase, and amplitude
69
# Define
Rarefaction
reduction in the density of something, especially air or a gas
70
# Define
Resolved harmonics
lower harmonics that are separated out in the cochlea (i.e., they excite distinct places on the basilar membrane)
71
# Define
Resonance
the phenomena of amplification that occurs when the frequency of a periodically applied force is in harmonic proportion to a natural frequency of the system on which it acts
72
# Define
Resonant frequency
a natural frequency of vibration determined by the physical parameters of the vibrating object
73
# Define
Reverberation time
the time it takes sound to decrease by 1/1000th of its original pressure
74
# Define
Scale illusion
an auditory illusion in which principles of grouping by frequency, proximity, and spatial location are put into conflict and in which frequency proximity wins out
75
# Define
Sound
vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear.
76
# Define
Sound pressure level (SPL)
the pressure level of a sound, measured in decibels (dB)
77
# Define
Sound wave
a wave of compression and rarefaction, by which sound is propagated in an elastic medium such as air.
78
# Define
Spaciousness factor
fraction of all the sound received by listener that is indirect
79
# Define
Stapes
a small stirrup-shaped bone in the middle ear, transmitting vibrations from the incus to the inner ear.
80
# Define
Subcortical structures
a group of diverse neural formations deep within the brain which include the diencephalon, pituitary gland, limbic structures and the basal ganglia.
81
# Define
Superior olivary nucleus
a group of nuclei located in the brainstem near the junction of the pons and medulla. It is the first auditory relay after the cochlear nucleus on the way to the auditory cortex and is the major point at which information from the two ears is integrated.
82
# Define
Tectorial membrane
an extracellular connective tissue that covers the mechanically-sensitive hair bundles of the sensory receptor cells in the inner ear.
83
# Define
Temporal coding
a type of neural coding which relies on precise timing of action potentials or inter-spike intervals
84
# Define
Timbre
the character or quality of a musical sound or voice as distinct from its pitch and intensity.
85
# Define
Tip links
extracellular filaments that connect stereocilia to each other or to the kinocilium in the hair cells of the inner ear
86
# Define
Tonality
the arrangement of pitches and/or chords of a musical work in a hierarchy of perceived relations, stabilities, attractions and directionality
87
# Define
Tone height
perceptual experience of increasing pitch as tone's frequency (wavelength increases)
88
# Define
Tympanic membrane
a membrane forming part of the organ of hearing, which vibrates in response to sound waves. In humans and other higher vertebrates it forms the eardrum, between the outer and middle ear.
89
# Definition
an area through which sound waves fail to propagate, due to topographical obstructions or disruption of the waves via phenomena such as wind currents, buildings, or sound barriers
Acoustic shadow
90
# Definition
process of adding harmonics to create complex sounds
Additive synthesis
91
# Definition
the fluctuation or displacement of a wave from its mean value
Amplitude
92
# Definition
the modulation of a wave by varying its amplitude, used especially as a means of broadcasting an audio signal by combining it with a radio carrier wave
Amplitude modulation
93
# Definition
the detection of modulation versus the detection of modulation rate
Amplitude-modulated noise
94
# Definition
sound whose pattern does not repeat itself as do those of the periodic sounds
Aperiodic sounds
95
# Definition
changes occurring before the sound reaches its steady-state intensity
Attack
96
# Definition
the relationship between the threshold of hearing for a pure tone, expressed in decibels sound-pressure level (dB SPL), and the frequency of the tone
Audibility curve
97
# Definition
canal leading from the opening of the external ear to the eardrum
Auditory canal
98
# Definition
describes an organism's ability to perceive the location of the source of a sound
Auditory localisation
99
# Definition
falls between the audibility curve and and the. threshold for feeling
Auditory
100
# Definition
a proposed model for the basis of auditory perception. This is understood as the process by which the human auditory system organizes sound into perceptually meaningful elements
Auditory scene analysis
101
# Definition
surrounds an observer and exists wherever there is sound
Auditory space
102
# Definition
the perceptual grouping of sounds, to form coherent representations of objects in the acoustic scene, and is a fundamental aspect of hearing and speech perception
Auditory stream segragation
103
# Definition
the direction of a celestial object from the observer, expressed as the angular distance from the north or south point of the horizon to the point at which a vertical circle passing through the object intersects the horizon.
Azimuth
104
# Definition
a stiff structural element within the cochlea of the inner ear which separates two liquid-filled tubes that run along the coil of the cochlea, the scala media and the scala tympani.
Basilar membrane
105
# Definition
ratio of low to middle frequencies reflected from surfaces
Bass ratio
106
# Definition
the secondary auditory cortex immediately surrounding the core
Belt area
107
# Definition
any difference in the sound arriving at the two ears from a given sound source (interaural difference) that acts as a cue to permit auditory localization
Binaural cues
108
# Definition
The frequency of a sound at which the threshold of a single fibre of an auditory nerve is lowest and to which it is therefore most responsive
Characteristic frequency
109
# Definition
the mechanosensing organelles of hair cells, which respond to fluid motion in numerous types of animals for various functions, including hearing and balance
Cilia
110
# Definition
a spiralled, hollow, conical chamber of bone, in which waves propagate from the base (near the middle ear and the oval window) to the apex (the top or center of the spiral)
Cochlea
111
# Definition
a positive feedback loop within the cochlea that amplifies the traveling wave
Cochlear amplifier
112
# Definition
the obligatory nucleus in which all ascending information from the cochlea forms synaptic connections with the auditory brain
Cochlear nucleus
113
# Definition
the context of neurobiology is a process by which a neuron or a neural circuit can encode information by detecting the occurrence of temporally close but spatially distributed input signals
Coincidence detectors
114
# Definition
part of a sound wave where the density is higher than normal
Condensation
115
# Definition
rate at which the music fades to silence
Decay
116
# Definition
sound that reaches the listener's ears straight from the source
Direct sound
117
# Definition
Removal of the first harmonic in a sound with the same perceived pitch, but with a different timbre
Effect of the missing fundamental
118
# Definition
the measured brain response that is the direct result of a specific sensory, cognitive, or motor event
Event related potential
119
# Definition
another term for the fundamental frequency which sets the repetition rate
First harmonic
120
# Definition
the number of occurrences of a repeating event per unit of time
Frequency
121
# Definition
display of harmonics of a complex sound
Frequency spectrum
122
# Definition
the lowest frequency of a periodic waveform
Fundamental
123
# Definition
the lowest frequency which is produced by the oscillation of the whole of an object, as distinct from the harmonics of higher frequency
Fundamental frequency
124
# Definition
the sensory receptors of both the auditory system and the vestibular system in the ears of all vertebrates, and in the lateral line organ of fishes
Hair cells
125
# Definition
a signal or wave whose frequency is an integral (whole-number) multiple of the frequency of some reference signal or wave
Harmonic
126
# Definition
the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second
Hertz (Hz)
127
# Definition
a bone in the middle ear. The anvil-shaped small bone is one of three ossicles in the middle ear
Incus
128
# Definition
sound that is reflected off of environmental surfaces and then to the listener
Indirect sound
129
# Definition
the principal midbrain nucleus of the auditory pathway and receives input from several peripheral brainstem nuclei in the auditory pathway, as well as inputs from the auditory cortex
Inferior colliculus
130
# Definition
the sensory cells of the cochlea, are responsible for signal transduction
Inner hair cells
131
# Definition
the difference in loudness and frequency distribution between the two ears
Interaural level difference (ILD)
132
# Definition
the difference in arrival time of a sound between two ears
Interaural time difference (ITD)
133
# Definition
time between when sound leaves its source and when the first reflection arrives
Intimacy time
134
# Definition
a neurocomputational model that explains how auditory systems can register and analyze small differences in the arrival time of sounds at the two ears in order to estimate the direction of sound sources in the azimuthal plane.
Jeffress model
135
# Definition
the subjective perception of sound pressure
Loudness
136
# Definition
a hammer-shaped small bone or ossicle of the middle ear which connects with the incus and is attached to the inner surface of the eardrum
Malleus
137
# Definition
part of the auditory thalamus and represents the thalamic relay between the inferior colliculus (IC) and the auditory cortex (AC).
Medial geniculate nucleus
138
# Definition
a sequence of single notes that is musically satisfying; a tune.
Melody
139
# Definition
the portion of the ear internal to the eardrum, and external to the oval window of the inner ear
Middle ear
140
# Definition
two muscles which serve a protective function in the middle ear; the tensor tympani and stapedius
Middle ear muscles
141
# Definition
relies on sounds reaching a single ear to constrain the set of possible sound sources
Monaural cue
142
# Definition
the interval between one musical pitch and another with double its frequency
Octave
143
# Definition
sounds that start at different times are likely to come from different sources
Onset time
144
# Definition
the receptor organ for hearing and is located in the mammalian cochlea. This highly varied strip of epithelial cells allows for transduction of auditory signals into nerve impulses' action potential.
Organ of Corti
145
# Definition
three bones in either middle ear that are among the smallest bones in the human body.
Ossicles
146
# Definition
the external portion of the ear, which consists of the auricle (also pinna) and the ear canal
Outer ear
147
# Definition
a membrane-covered opening that leads from the middle ear to the vestibule of the inner ear
Oval window
148
# Definition
sounds which repeats itself at regular intervals
Periodic sounds
149
# Definition
Removal of the first harmonic in a sound with the same perceived pitch, but with a different timbre
Periodicity pitch
150
# Definition
the mechanism by which the peripheral auditory system keeps track of the times of occurrence of the ongoing amplitude fluctuations in sounds
Phase locking
151
# Definition
the external part of the ear in humans and other mammals; the auricle
Pinnae
152
# Definition
a theory of hearing that states that our perception of sound depends on where each component frequency produces vibrations along the basilar membrane
Place theory
153
# Definition
a binaural psychoacoustical effect. When a sound is followed by another sound separated by a sufficiently short time delay (below the listener's echo threshold), listeners perceive a single auditory event
Precedence effect
154
# Definition
the loss of hearing that gradually occurs in most individuals as they grow older
Presbycusis
155
# Definition
part of the temporal lobe that processes auditory information in humans and many other vertebrates
Primary auditory cortex (A1)
156
# Definition
a sound with a sinusoidal waveform; that is, a sine wave of any frequency, phase, and amplitude
Pure tone
157
# Definition
reduction in the density of something, especially air or a gas
Rarefaction
158
# Definition
lower harmonics that are separated out in the cochlea (i.e., they excite distinct places on the basilar membrane)
Resolved harmonics
159
# Definition
the phenomena of amplification that occurs when the frequency of a periodically applied force is in harmonic proportion to a natural frequency of the system on which it acts
Resonance
160
# Definition
a natural frequency of vibration determined by the physical parameters of the vibrating object
Resonant frequency
161
# Definition
the time it takes sound to decrease by 1/1000th of its original pressure
Reverberation time
162
# Definition
an auditory illusion in which principles of grouping by frequency, proximity, and spatial location are put into conflict and in which frequency proximity wins out
Scale illusion
163
# Definition
vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear.
Sound
164
# Definition
the pressure level of a sound, measured in decibels (dB)
Sound pressure level (SPL)
165
# Definition
a wave of compression and rarefaction, by which sound is propagated in an elastic medium such as air.
Sound wave
166
# Definition
fraction of all the sound received by listener that is indirect
Spaciousness factor
167
# Definition
a small stirrup-shaped bone in the middle ear, transmitting vibrations from the incus to the inner ear.
Stapes
168
# Definition
a group of diverse neural formations deep within the brain which include the diencephalon, pituitary gland, limbic structures and the basal ganglia.
Subcortical structures
169
# Definition
a group of nuclei located in the brainstem near the junction of the pons and medulla. It is the first auditory relay after the cochlear nucleus on the way to the auditory cortex and is the major point at which information from the two ears is integrated.
Superior olivary nucleus
170
# Definition
an extracellular connective tissue that covers the mechanically-sensitive hair bundles of the sensory receptor cells in the inner ear.
Tectorial membrane
171
# Definition
a type of neural coding which relies on precise timing of action potentials or inter-spike intervals
Temporal coding
172
# Definition
the character or quality of a musical sound or voice as distinct from its pitch and intensity.
Timbre
173
# Definition
extracellular filaments that connect stereocilia to each other or to the kinocilium in the hair cells of the inner ear
Tip links
174
# Definition
the arrangement of pitches and/or chords of a musical work in a hierarchy of perceived relations, stabilities, attractions and directionality
Tonality
175
# Definition
perceptual experience of increasing pitch as tone's frequency (wavelength increases)
Tone height
176
# Definition
a membrane forming part of the organ of hearing, which vibrates in response to sound waves. In humans and other higher vertebrates it forms the eardrum, between the outer and middle ear.
Tympanic membrane
177
What are the two different definitions of sound?
1. Physical definition: sound is created by pressure changes in the air or other medium
2. Perceptual definition: sound is the experience we have when we hear
178
How do loud speakers produce sound?
* The diaphragm of the speaker moves out, pushing air molecules together called condensation.
* The diaphragm also moves in, pulling the air molecules apart called rarefaction.
* The cycle of this process creates alternating high- and low-pressure regions that travel through the air.
179
What is the term used to describe our perception of sound amplitude?
Loudness
180
What unit is loudness measured in?
Decibels (dB)
181
The higher the amplitude, the ________ the loudness
The higher the amplitude, the **higher** the loudness
182
What unit is frequency measured in?
Hertz (Hz)
183
What is the term used to describe our perception of frequency?
Pitch
184
What is tone height?
Tone height is the increase in pitch that happens when frequency is increased.
185
\_\_\_\_\_\_\_\_\_\_\_\_ is the repetition rate and is called the first harmonic
**Fundamental frequency** is the repetition rate and is called the first harmonic
186
\_\_\_\_\_\_\_\_\_\_\_ - process of adding harmonics to create complex sounds
\_\_\_\_\_\_\_\_\_\_\_\_ - display of harmonics of a complex sound
\_\_\_\_\_\_\_\_\_\_\_\_\_ - buildup of sound at the beginning of a tone
\_\_\_\_\_\_\_\_\_\_\_ - decrease in sound at end of tone
\_\_\_\_\_\_\_\_\_\_ - basically a function of frequency; the perceived pitch of complex sound is determined by the fundamental frequency
**Additive synthesis -** process of adding harmonics to create complex sounds
**Frequency spectrum -** display of harmonics of a complex sound
**Attack of tones -** buildup of sound at the beginning of a tone
**Decay of tones -** decrease in sound at end of tone
**Pitch -** basically a function of frequency; the perceived pitch of complex sound is determined by the fundamental frequency
187
What does timbre reflect?
The number and magnitude of harmonics
188
Why do different musical instruments playing the same chord sound different?
Timbre - even though the fundamental frequency is the same, the higher order harmonics differ
189
What happens when you remove the first harmonic of a complex periodic sound?
Removal of the first harmonic results in a sound with the same perceived pitch, but with a different timbre.
\>This is called a periodicity pitch
190
What is the range of human hearing?
20 to 20,000 Hz
191
What are the names of the boundaries of the auditory response area of the auditory curve?
Threshold of feeling
Threshold of hearing
192
193
194
195
What is being shown in this diagram?
(a) Movement of hair cilia in one direction opens ion channels in the hair cell, which results in the release of neurotransmitter onto an auditory nerve fiber; (b) Movement in the opposite direction closes the ion channels so there is no ion flow and no transmitter release.
196
What are the two ways nerves fibers signal frequency?
* *Which* fibers are responding
* Specific groups of hair cells on basilar membrane activate a specific set of nerve fibers;
* *How* fibers are firing
* Rate or pattern of firing of nerve impulses
197
What is Bekesys' Place Theory of Hearing? How was it determined?
Frequency of sound is indicated by the place on the organ of Corti that has the highest firing rate.
Békésy determined this in two ways:
* Direct observation of the basilar membrane in cadavers.
* Building a model of the cochlea using the physical properties of the basilar membrane.
198
Which part of the cochlea receives low frequencies? Which receives high frequencies?
Base: High frequencies (~20,000 Hz)
Apex: Low frequencies (~20 Hz)
199
How does the base of the basilar membrane differ physically to the apex?
Base of the membrane (by stapes) is:
* Three to four times narrower than at the apex.
* 100 times stiffer than at the apex.
200
What is this diagram showing?
A perspective view showing the traveling wave motion of the basilar membrane. This picture shows what the membrane looks like when the vibration is “frozen,” with the wave about two thirds of the way down the membrane. (From Tonndorf, 1960). A tone causes different points of the membrane to move up and down (out of phase
201
Envelope of the traveling wave:
1. Indicates \_\_\_\_\_\_\_\_
2. Hair cells at this point are \_\_\_\_\_\_
3. Position of the peak is a function of \_\_\_\_\_\_\_\_\_\_.
Envelope of the traveling wave:
1. Indicates **the point of maximum displacement of the basilar membrane**
2. Hair cells at this point **are stimulated the most strongly leading to the nerve fibers firing the most strongly at this location.**
3. Position of the peak is a function of **frequency.**
202
What is this diagram showing?
The outer hair cells (a) elongate when cilia bend in one direction; (b) contract when the cilia bend in the other direction. This results in an amplifying effect on the motion of the basilar membrane – ‘mechanical frequency tuning’
203
What is this diagram showing?
How hair cell activation and auditory nerve fiber firing area synchronized with pressure changes of the stimulus. The auditory nerve fiber fires when the cilia are bent to the right. This occurs at the peak of the sine-wave change in pressure.
204
In which structures do auditory nerve fibers synapse?
Cochlear nucleus
Superior olivary nucleus
Inerior colliculus
Medial geniculate nucleus
Auditory receiving area (A1)
205
Hierarchical processing occurs in the cortex
* Neural signals travel through the \_\_\_\_, then \_\_\_\_\_, followed by the \_\_\_\_\_\_area.
* Simple sounds cause activation in the \_\_\_\_\_\_area.
* \_\_\_\_\_\_and \_\_\_\_\_\_\_\_\_areas are activated in response to more complex stimuli made up of many frequencies.
Hierarchical processing occurs in the cortex
* Neural signals travel through the **core**, then **belt**, followed by the **parabelt** area.
* Simple sounds cause activation in the **core** area.
* **Belt** and **parabelt** areas are activated in response to more complex stimuli made up of many frequencies.
206
207
What are the three main auditort areas?
Core area
Belt area
Parabelt area
208
Which of the three main auditory areas is the primary auditory receiving area (A1) located?
Core area
209
How are neurons arranges in A1?
Tonotopic maps are found in A1
* Neurons that respond better to low frequencies are on the left and those that respond best to high frequencies are on the right.
210
211
True or False:
People find locating sounds behind them the most difficult
True
212
True or False:
Location cues are not contained in the receptor cells like on the retina in vision
True
213
Processing of interaural disparity cues occurs in the _____________ - first site of binaural interaction
Processing of interaural disparity cues occurs in the **superior olivary complex (SOC)** - first site of binaural interaction
214
What is this diagram showing?
The principle behind interaural time difference (ITD). The tone directly in front of the listener, at A, reaches the left and the right ears at the same time. However, when the tone is off to the side, at B, it reaches the listener’s right before it reaches the left ear.
215
For what type of frequencies is an acoustic shadow relvant for? Why
Only relevant for high frequencies
The spaces between high-frequency sound waves is small compared to the head. The head interferes with the sound waves, creating an acoustic shadow on the other side of the head. Whereas, the spacing between low-frequency sound waves is large compared to the person’s head, so the sound is unaffected by the head.
216
What structure creates the acoustic shadow?
Head
217
Why are ILD and ITD not effective for judgments on elevation?
In many locations they may be equal (cone of confusion)
218
What two mechanisms have been proposed for source localisation?
Narrowly tuned ITD neurons
* They are found in the inferior colliculus and the superior olivary nuclei.
* This response is a form of specificity coding.
Broadly-tuned ITD neurons
* Research on gerbils indicates that neurons in the left hemisphere respond best to sound from the right, and vice versa.
* Location of sound is indicated by the ratio of responding for two types of neurons.
* This is a distributed coding system
219
What is this image describing?
How the Jeffress circuit operates. Axons transmit signals from the left ear (blue) and right ear (red) to neurons, indicated by circles. (a) Sound in front: signals start in left and right channels simultaneously. (b) Signals meet at neuron 5, causing it to fire. (c) Sound to the right: signal starts in the right channel first. (d) Signals meet at neuron 3, causing it to fire.
220
Identifying the sources of sound is largely a *top-down/bottom-up* process
Identifying the sources of sound is largely a **top-down** process
221
What heuristics help to perceptually organise sound stimuli?
Onset time
Location
Similarity of timbre and pitch
222
What does this image describe?
(a) When high and low tones are alternated slowly, auditory stream segregation does not occur, so the listener perceives alternating high and low tones. (b) Faster alternation results in segregation by grouping of pitch into high and low streams
