Frequency Selectivity and Psychoacoustic Masking

Question 1

the ability to detect one sound in the presence of another different sound

Answer 1

frequency selectivity

Question 2

define masking

Answer 2

masking occurs when one sound raises the threshold of another sound

Question 3

What is partial masking?

Answer 3

occurs when one sound makes another sound more difficult to detect but doesn’t raise the threshold

Question 4

what is the masker?

Answer 4

the sound that is increasing the threshold of another sound

Question 5

test/probe signal is what?

Answer 5

the sound that is being masked

Question 6

what is the amount of masking?

Answer 6

the amound in dB of the threshold shift (unmasked)

Question 7

If an unmasked threshold is 40 dB SPL and a masked threshold is 50 dB SPL, what is the amount of masking?

Answer 7

10 dB SPL

Question 8

If an unmasked threshold is 50 dB SPL and a masked threshold is 70 dB SPL, what is the amount of masking?

Answer 8

20 dB SPL

Question 9

If an unmasked threshold is 15 dB SPL and a masked threshold is 55 dB SPL, what is the amount of masking?

Answer 9

40 dB SPL

Question 10

What factors influence the amount of masking?

Answer 10

intensity of the masker
spectral characteristics of the masker relative to the maskee or tone being masked
temporal characteristics of the masker (steady state vs. fluctuating amplitude)

Question 11

Describe Fletcher’s critical bandwidth experiment. What were his findings?

Answer 11

he asked “does increasing the bandwidth of the masker further raise the threshold of the maskee?” (how much of white noise actually contributes to the masking of a tone?)
He found that increasing the bw of the basker does this but to a point and beyond that point there is no further increase of threshold of the maskee. lead to the model of bm as a bank of overlapping filters. filter bw is approx 19% of the center frequency