1
Q
What are the physical definitions and the perceptual definitions of sound
A
Physical
- > sound is pressure changes in the air or other medium
- > transmits vibrations
Perceptual
->sound is the experience we have when we hear
2
Q
Compare condensation to rarefaction
A
Condensation
- > pressure increases
- > density of the molecules near the source increases
Rarefaction
- > pressure decreases
- > density of molecules near the source decreases
3
Q
What are pure tones? Where are they produced?
A
- pure tones occur when changes in the air pressure occur in a pattern
- > specifically a sine wave pattern
- > they occur occasionally within the environment
-note tuning forks, whistling or flutes can produce pure tones as well
4
Q
What is frequency and amplitude referring to
A
Frequency
->number of cycles per second
Amplitude(dB)
->would be the size of the pressure change
5
Q
What frequencies can humans perceive
A
-they can perceive from 20Hz to 20kHz
6
Q
Do complex tones waveforms repeat?What is this repetition rate referred to as
A
- yes it does
- > because like a pure tone, it is a periodic tone
-note that repetition rates are referred to as the fundamental frequency
7
Q
How is the complex tone related to the pure tone
A
- complex tones are made up of a number of pure tones(sine wave) components added together
- > the first harmonic is referred to as the fundamental tone
- > higher harmonics are pure tones with whole numbers multiples of the fundamental tone
8
Q
What is a frequency spectra?
A
- it is another way to represent the harmonic components of a complex tone
- horizontal axis is frequency instead of time
- the position of each line on the horizontal line indicates the frequency of each of the tone’s harmonics
- height indicates the harmonic’s amplitude
9
Q
What would happen to the repetition rate if you removed a harmonic? Let’s say you removed the fundamental of the tone(first harmonic)
A
- the repetition rate would not change
- >there is still information in the waveform indicating the fundamental frequency
10
Q
What is loudness in terms of perception
A
- loudness is the perceptual quality most closely related to level or amplitude
- > eg; increasing the sound level by increasing from 40 dB to 50 dB increases the loudness by 2
11
Q
What is the audibility curve indicate? What is the range of hearing?What is the most sensitive hearing range?
A
- it is a curve which indicates the threshold of hearing vs frequency
- we are most sensitive to sounds between frequencies of 2000 and 4000
12
Q
What is the auditory response area
A
-tones that we can hear fall within this area
13
Q
What is the threshold of feeling
A
- tones with high amplitude
- > these are painful tones that we can feel
-threshold of feeling is are the upper boundary of the auditory response area
14
Q
How is frequency and loudness related
A
- at each frequency, there is a threshold or baseline
- >decibels at which it can be heard
15
Q
What is an equal loudness curve
A
- a way of looking at the relationship between frequency and loudness
- > this curve shows the same perception of loudness at different frequencies
- note that at threshold
- > the level of loudness can vary for different frequencies
- > at some levels above threshold, different frequencies can have a similar loudness at the same decibel
16
Q
What is pitch? What is it associated with?
A
- pitch is the perceptual quality that use to describe as high or low
- pitch can be associated with the musical scale or property of speech
- it is a psychological property of sound
- > not a physical one
17
Q
How is pitch related to fundamental frequency
A
- pitch is most closely related to fundamental frequency
- low fundamental frequencies= low pitches
18
Q
What is tone height
A
- it is the increasing pitch that accompanies increases in a tone’s fundamental frequency
- > it occurs as you move from the low to the high end of the piano keyboard
19
Q
Tone chroma
A
- notes with the same letter on the piano sound similar
- > every time you pass the same letter on the piano, you are going up an octave
- > tones separated by the octaves have the same tone chroma
- within the same chroma, the fundamental frequency are separated by multipes of two
20
Q
Effect of the missing fundamental
A
- the tone or pitch of a sound remains the same
- >even when you have removed a harmonic or the fundamental harmonic
21
Q
What is timbre
A
- it distinguishes between two tones that have the same loudness, pitch and duration
- > they still sound different tho
22
Q
How is timbre created
A
-it is created by the differences in harmonics
23
Q
What else is timbre related to other than differences in harmonics
A
- it is related to time course
- specifically, the time course of a tone’s attack and that of a tone’s decay
- attack is the buildup of sound at the beginning of the tone
- decay is the decrease in sound at the end of the tone
24
Q
What are aperiodic sounds?
A
- they are sound waves that do not repeat
- >eg; a door slamming shut or people talking or noises such as static on radio
25
How do ossicles help in transferring air vibrations on to the inner ear?
- concentrate the vibrations of the large tympanic membrane onto the much smaller stapes
- >increases pressure by a factor of 20
- the ossicles are hinged
- >creates a lever action
26
What are middle ear muscles
- smallest skeletal muscles in the body
- at very high sound
- >they dampen the ossicles vibrations
- >reduces transmission of low frequency sounds
- >helps prevent low frequencies from interfering with the perception of high frequency sounds
27
What is the upper half of the cochlea called? What is the bottom half? What are they separated by?
- upper half is called the scala vestibuli
- lower half is called the scala tympani
- they are separated by a structure called the cochlear partition
28
What is the important thing that the Organ of corti contain
- they contain the hair cells
| - >these are the receptors crucial for hearing
29
Where do cilia protrude from
- they protrude from hair cells
| - human beings contain one row of inner hair cells and about three rows of outer hair cells
30
Describe the bending if cilia and this relation to tip links
- bending causes structures tip links to stretch
- >tip links link different cilia
- >this stretching opens ion channels in the membrane of the cilia
- >potassium ions flow into the cell and an electrical signal result
- >neurotransmitters released at the synapse separating the inner hair cells from the auditory nerves
- when cilia bend other way
- >tip links slacken
- >ion channels close
- >ion flow stops
31
Where does the organ of corti sit? Which membrane? And which membrane is above it?
- organ of corti sits on the basilar membrane
| - >tectorial membrane is arched over the hair cells
32
Describe the process of when the oval window sends vibrations to the cochlea? How this affects the basilar membrane
- oval window transmits vibrations to the liquid inside the cochlea
- sets the basilar membrane in motion
- organ of corti has up and down motion
- tectorial membrane moves back and forth
- >causes the cilia of the outer hair cells to bend
- >the cilia of other outer hair cells and inner hair cells bend in response to pressure waves in the liquid
33
What is phase locking?
- property of firing at the same place in the sound stimulus
- overall firing matches the frequency of the sound stimulus
- sound's repetition rate produces a pattern of nerve firing in which the timing of nerve spikes matches the timing of the repeating sound stimulus
34
What motion does the basilar membrane vibration resemble
- it resembles that of a travelling wave
- >like when the person holds a rope and snaps it
- >sending a wave travelling down the rope
- note most of the basilar membrane vibrates but some more than others
- >the place that vibrates the most DEPENDS on the frequency of the tone
35
What happens to vibrations on the basilar membrane as frequency changes
- as frequency increases
- >the places on the membrane that vibrates the most moves from the apex at the end of the cochlea to the base at the oval window
36
What is a tonotopic map
-it is a map of the various frequencies in the cochlea
37
What is a neural frequency tuning curve
- it is a measurement of the response of auditory nerve fibers to specific frequencies
- present pure tones of different frequencies
- >measure the sound level necessary to cause the neuron to increase its firing above the baseline
38
How is the cochlea's filtering action reflected by the tuning curve
1)Neurons respond best to one frequency
2) Each frequency is associated with nerve fibers located along specific locations in the basilar membrane
3) Curves become wider at higher frequencies
- >filtering of the sounds is more selective at lower frequencies
39
Where does the Cochlear amplifier take place? What does it do?
- takes place outer hair cells
- major purpose of outer hair cells is to influence how the basilar membrane vibrates
- >they accomplish this by changing length
- ion flow in outer hair cells cause it to expand and contract
- >they become elongated when cilia bends in one direction and contracts when it bends in the other
- >this movement of contraction and expansion increases the motion of the basilar membrane
- >it also sharpens its response to specific frequencies
40
Summarize how the cochlear implant influences the tuning in each place of the cochlea
-it greatly sharpens the tuning of each place in the cochlea
41
What is the place theory?
-relation between sound frequency and the place along the basilar membrane when it is activated
42
What are reasons against place theory
- one argument was based on the effect of the missing fundamental
- >this did not change the pitch
- >a tone which has fundamental frequency of 200 has the same frequency after the 200 Hz is removed
- >there is no longer peak vibration at the place associated with 200 Hz
43
What is amplitude modulated noise? How does it go against place theory
- sound that isn't associated with the vibration of the basilar membrane
- >but it still created a perception of a pitch
- >the level or intensity of the sound fluctuated up and down rapidly
-therefore, pitch is perceived even in the absence of place information
Psych 367
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