pitch

Question 1

pitch

Answer 1

the “attribute of auditory sensation in terms of which sounds may be ordered on a musical scale” (ANSI, 1994)

Question 2

frequency discrimination

Answer 2

How sensitive are you to changes in something, can you tell that its not the same as before? Rule: at 1000hz the freq different limen is about 2hz.
around .2-.3 of a %. need larger greq different to tell things apart.

Question 3

limen

Answer 3

threshold for frequency

Question 4

2 ways to determine pitch of pure tones

Answer 4

temporal code; place code

Question 5

phase locking

Answer 5

you can see when the neuron fires in relation to the cycle of the stimulus. time tells you when spikes occur in relation to when the cycle began
Neurons are firing systematically. They’re sensitive to where you are in the waveform. When they’re firing its orderly.

Question 6

temporal code

Answer 6

So if your neurons fire regularly and you can tell, then you can mentally figure out that THIS is the certain freq youre listening to.
You can use time (time between) the neural firings which will tell you the period of the cycle to calculate what the frequency actually is.

Question 7

Synchrony index

Answer 7

how well the firings fit into 1 half of a cycle of a waveform.
The better the neuron is firing into that cycle, the better our index is.
harder to fire and reload for high freq

Question 8

volley principle

Answer 8

safety net at 4kHz
as the freq increases, what youre doing is working with a # of diff fibers that are working together. Its phase locked, just not on every cycle.

Use info from multiple neurons to get phase lock info up to 4kHz

Question 9

place code

Answer 9

von bekesy.
Basilar membrane is already encoding in diff freq, so lets pay attention to which is firing. If its this place, its higher freq than this place.
Think about auditory nerve position 1 firing at low freq and position 2 firing at high freq. we can tell theyre different freqs because of the position along the BM

Question 10

Pure tones: Timing code vs Place code

Answer 10

low freq: timing AND place. High freq: place only.
Phase locking only for tones below 4 kHz.
Frequency difference threshold increases rapidly above 4 kHz.
Musical pitch absent above ~4 kHz (top of piano)

Question 11

pitch of complex waveforms

Answer 11

most = periodic.
spectra has harmonics (integer multiples of the fundamental)
pitch of a complex periodic tone is close to the pitch of a sine wave @ fundamental
The pitch that you hear is the lowest component/fundament freq.

Question 12

Place theory

Answer 12

Helmholtz; pitch is heard @ fundamental because fundamental freq is the highest level low-freq component; thus gives lowest freq peak on BM

Question 13

Helmholtz hypothesis/prediction?

Answer 13

(Hypothesis) If the pitch of a complex waveform is heard at the fundamental because the fundamental frequency is the highest level low-frequency component and thus gives the lowest frequency peak on the basilar membrane…

(Prediction) Then, the pitch should change if the energy at the fundamental frequency is removed.

Question 14

Seebeck’s siren

Answer 14

a place theory test.created a stimulus where the low freq component is gone and the new pitch should be 2/T. B and C should be the same pitch, but they’re not! A and C are.

Question 15

Virtual pitch

Answer 15

pitch of the missing fundamental

Question 16

distortion

Answer 16

Helmholtz (who favored place theory) countered Seebeck’s results by suggesting that the ear reintroduces energy at the fundamental by a process of distortion
not intended to be presented..just shows up!

Question 17

how distortion works

Answer 17

Distortion produces energy at frequencies corresponding to the difference between two components physically present (i.e. at the harmonic spacing).

Any pair of adjacent harmonics would generate energy at the fundamental. (explanation)

Question 18

Evidence against place theory

Answer 18

Near threshold listening; masking; pitch shift

Question 19

Virtual pitch: near threshold listening

Answer 19

high level sounds can produce distortion, where low level sounds dont.
(Hypothesis) If virtual pitch is heard because the ear reintroduces energy at the fundamental by a process of distortion…
(Prediction) Then, the pitch should disappear if the harmonics do not produce distortion.
Listeners can still detect a virtual pitch with low-level sounds, so virtual pitch cannot be attributed to distortion.

Question 20

Virtual pitch: masking noise

Answer 20

(Hypothesis) If virtual pitch is heard because the ear reintroduces energy at the fundamental by a process of distortion…
(Prediction) Then, the pitch should disappear (or at least change) if the energy at the fundamental frequency is masked.
aka if distortion was generating this tone, then we couldn’t mask it.

Question 21

Virtual pitch: pitch shift

Answer 21

(Hypothesis) If virtual pitch is heard because the ear reintroduces energy at the fundamental by a process of distortion…
(Prediction) Then, the pitch should remain constant so long as the frequency separation between the component tones remains constant
didn’t work. the pitch was shifting

Question 22

temporal theory

Answer 22

Schouten (1941) proposed that the brain times the intervals between beats of unresolved harmonics of a complex sound, in order to find the pitch. pith is based on the period of the waveform.

Question 23

evidence against temporal theory

Answer 23

dominant region; cross ear pitch

Question 24

virtual pitch: dominance region

Answer 24

(Hypothesis) If virtual pitch is heard because the brain times the intervals between beats of unresolved harmonics of a complex sound

(Prediction) Then, unresolved harmonics should produce more salient pitch than resolved harmonics

Question 25

virtual pitch dominance region experiment

Answer 25

Changes in the frequency of components in the dominant region influence the pitch of a complex sound more strongly than in any other frequency region. dominance region should be at high freq (>~2khz), BUT the dominant region of pitch perception is 600-1400 where harmonics are resolved

Question 26

virtual pitch: cross-ear pitch

Answer 26

(Hypothesis) If virtual pitch is heard because the brain times the intervals between beats of unresolved harmonics of a complex sound

(Prediction) Then, there should be no virtual pitch if consecutive frequency components go to opposite ears.
place 1 tone in each ear and theyre in isolation because they’re in different filters because theyre in diff ears. listeners could still hear a virtual pitch! means dont need to interact temporally in the cochlea. (no distortion)

Question 27

pattern recognition theory

Answer 27

if not place/temporal theory, then what is it?
Goldstein’s theory states that pitch is determined by a pattern recognition process on the resolved harmonics from both ears.

The brain finds the best-fitting harmonic series to the resolved frequencies, and takes its fundamental as the pitch.