Psychoacoustics lll

Question 1

What are the two general criteria that the frequency discrimination limen can be measured?

Answer 1

Absolute terms Δf or relative terms Δf/f (Weber’s fraction)

Question 2

How do the methods to measure intensity discrimination compare to frequency discrimination? (3)

Answer 2

Gated Pulse tone method: must be used with appropriate methods to reduce splattering.
Continuous Pulse Tone Increment method: is a simultaneous presentation, so not suitable for frequency discrimination tasks due to pitch “fusion.”
Modulation Tone: should be changed to frequency modulation instead of amplitude modulation.

Question 3

What are the two methodological concerns?

Answer 3

Pitch fusion: Two tones of different frequencies (larger than the Δf) can produce a fused pitch (one pitch) if they are presented simultaneously or close; this is called pitch fusion. The sequential presentation should be used to avoid fusion. Frequency splitting (or splattering): When a tone is turned on and off quickly, the frequency will spread to an unwanted region.

Question 4

What are the two situations that masking is used to help alleviate methodological concerns?

Answer 4

Shallow ramp & Masking with notch noise.

Question 5

Describe the take-home of what is happening in this image.

Answer 5

The relationship between the frequency to both the sensation level and the frequency discrimination limen. In the low freq range, the minimum freq difference detected does not change much as freq increases (i.e., compare 125 Hz and 500 Hz). However, when the freq. is beyond 2000 Hz, Δf increases quickly with F: at the higher F, we need a larger Δf to recognize there is a difference. Overall, the Sound level impacts Δf: large Δf at the low sound levels, especially at high F and vice versa (discrimination limen for frequency is lower at higher sound levels)

Question 6

How does the pulsed signal compare to frequency modulation results for the frequency discrimination limen?

Answer 6

FM produces better or lower threshold or limens for frequency discrimination.

Question 7

What is the effect of stimulus duration on the frequency discrimination limen?

Answer 7

The Δf improves (gets smaller) up to durations of 100 to 200 ms

Question 8

When does pitch sensation exist?

Answer 8

Pitch sensation only exists when the sound is heard

Question 9

What can occur with pitch when two tones with different frequencies are played?

Answer 9

Two tones with different frequencies may evoke the same pitch if close enough in frequency and in time

Question 10

What does pitch change with (which acoustic parameter)?

Answer 10

Pitch changes with intensity

Question 11

What is pitch NOT LINEARLY related with?

Answer 11

Pitch is not linearly related with frequency

Question 12

What unit is used to measure pitch?

Answer 12

Mels

Question 13

What is the relationship between frequencies and MELS?

Answer 13

1000 mels: the pitch produced by a 1000 Hz tone of 40 dB SL

Question 14

How does MELS relate to the musical scale?

Answer 14

No direct relationship between Mels and musical scale

Question 15

How does the ratio vary between MELS and frequency?

Answer 15

Just the relationship between the two, no linear or quantitative between both. That ratio does not always hold.

Question 16

What is the unit to measure the critical band?

Answer 16

Bark is the unit for critical band and one bark is 1 critical band.

Question 17

How much does it measure on the basilar membrane?

Answer 17

No matter where you measure the 100 Mels, the change sin pitch corresponding in distance across the basillar membrane in 1.3mm.

Question 18

What determines the pitch?

Answer 18

Fundamental frequency determines the pitch

Question 19

What determines the timbre?

Answer 19

Harmonic components determine timbre

Question 20

What is the difference between the synthetic and analytic pitch?

Answer 20

Analytic pitch is the ability to hear the partials (harmonic components) as well as the fundamental requires training. Synthetic pitch is the single dominant pitch that arises from a complex tone–virtual pitch (we all have this).

Question 21

What is a beat?

Answer 21

If two tones are presented individually and simultaneously and their frequency are within several hundred hertz, you can hear the amplitude of the signal change.

Question 22

Describe the missing fundamental theory.

Answer 22

If a group of harmonics are presented and we sense the pitch of fundamental frequency even when it is not there. The harmonic not there in terms of energy BUT still hear the pitch corresponding to that.

(Extra Information: A complex periodic tone and energy is above 1200Hz: 1200, 1400, 1600Hz- so the spacing between the tones, the harmonics, is 200 Hz. When presenting this complex tone, and there is the missing 200Hz but all those higher harmonics are present, even if it is all above 1200Hz, STILL, the subject will match the pitch to 200Hz.)

Question 23

What are the two aspects of temporal processing?

Answer 23

-Discrimination and integration
-Resolution versus summation

Question 24

High temporal resolution is unique for auditory system due to the______________________ and the
_______________of the auditory signals

Answer 24

High temporal resolution is unique for auditory system due to the poor spatial resolution and the nature of the auditory signals

Question 25

What is Temporal resolution?

Answer 25

Ability to follow fast changes of
signal with time

Question 26

Temporal summation is also seen in ___________________ tasks

Answer 26

Discrimination tasks

Question 27

Spatial (binaural) summation is seen on
on _________________ , and many other aspects of auditory sensation

Answer 27

loudness

Question 28

What are the binaural benifits?

• _______________ summation
• Improved _________________
• Better __________________
• Better ___________________
• Against __________________

Answer 28

• Spatial summation
• Improved discrimination
• Better sound localization
• Better sound quality
• Against noise masking

Question 29

Fill in the blanks related to Sound localization:
- Tasks: _____________
- Analytic measures: _______________
- Signal presentation: __________________________

Answer 29

• Tasks: two planes
• Analytic measures: using tone signal
• Signal presentation: open field or earphone

Question 30

Fill in the blanks related to spectrum cues:

• Produced by ____________
• Exist in ______________
• The only cues in ______________
• Do not require ______________
• Help source _________________

Answer 30

• Produced by HRTF
• Exist in both planes
• The only cues in elevation
• Do not require both ears
• Help source localization in azimuth

Question 31

Fill in the blanks related to Localization in horizontal plan:

More accurate than in ________________
- Based upon ___________ cues
- ITD/IPD—_______ frequency
- ITD for the ________________,
- IPD for _____________ sound
- IID— _____________ frequency
- Error: larger in ____________ frequency
- Localization error and minimal audible angle
- Accuracy change with azimuth—best in ______ degree

Answer 31

More accurate than the vertical plan
- Based upon binaural cues
- ITD/IPD—low frequency
- ITD for the onset/offset,
- IPD for continuous sound
- IID—high frequency
- Error: larger in the middle frequency
- Localization error and minimal audible angle
- Accuracy change with azimuth—best in 0 degree