Hearing Threshold and Sensitivity

Question 1

Define Psychoacoustics

Answer 1

Psychoacoustics is defined as auditory perception and senstive to frequency amplitude phase and duration

Question 2

What is detection

Answer 2

How minimal a stimulus you can perceive

Question 3

What is recognition

Answer 3

Sense of having heard a stimulus before

Question 4

What is identification

Answer 4

Being able to identify a stimulus

Question 5

What is discrimination

Answer 5

Ability to tell 2 or more stimuli apart

Question 6

What is the threshold of audibility

Answer 6

the smallest level required for detection to the frequency of the tone

Question 7

What are the perceptual correlates of pitch, intensity, phase and time

Answer 7

Frequency-pitch
intensity- loudness
time- duration

Question 8

How are sensitivity and threshold related

Answer 8

Sensitivity and threshold are related as high sensitivity and low threshold mean the same thing
From 0-1 kHZ sensitivity improves by 6db
and worsens by 24db/octave

Question 9

What is the minimum audibility curve

Answer 9

The auditory response area. The plot of threshold detection levels as a function of frequency

Question 10

What is the minimum audibility field

Answer 10

MAF thresholds are SPLS for pure tones at the threshold of audibility in a free field (no headphones).
You are listening binaural to sound coming from speakers.
Need to place a microphone where the listener would sit in order to calibrate threshold pressures

Question 11

What is Minimum audible pressure

Answer 11

MAP are thresholds are SPLS for pure tones at the threshold of audibility at the listeners tympanic membrane (using headphones).
The earphones are not usually calibrated in terms of pressure
A test coupler is attached to the earphone to approximate properties of the outer ear
SPL at eardrum is estimated from SPL at coupler

Question 12

How are MAP and MAF different

Answer 12

MAF is done without headphones in a free environment while MAP is done with

Question 13

How do MAF and MAP curves relate in terms of threshold pressure

Answer 13

MAF thresholds are always lower than MAP thresholds with usually about 6-10 db

Mostly due to various factors( head diffraction, outer ear resonances and calibration differences

Question 14

What is the reference equivalent threshold sound pressure level; and how is it measured

Answer 14

RETSPLS- there are different types of earphones and different types of couplers

Question 15

What is a circum-aural earphone

Answer 15

Fits complexity over and around pinna and calibrated using artificial ear

Question 16

What is supraural earphones

Answer 16

Fits over (against) pinna and calibrated to 6cc coupler

Question 17

What is intra aural (insert) headphones-

Answer 17

Inserted earphones into outer ear canal and calibrated with occuluded ear stimulato

Question 18

Define dB hearing level

Answer 18

the point of view of human hearing all of these different sound pressure levels have equal hearing level - they are all equally barely audible

Softest sound barely audible = 0dB HL

Question 19

What is an audiogram

Answer 19

When the detection of tones of different frequencies is plotted in dB HL instead of dB SPL

Question 20

What are the effects of age, sex and noise on exposure of hearing thresholds

Answer 20

Age- thresholds for frequencies above 4000 hz increase above 50 years

Sex: Slight female advantage

Noise exposure: Brief exposure to very loud noise (gunshot) or persistent exposure to sounds greater than 85db

Causes damage to hairs in the cochlea

Question 21

What are the duration effects to threshold of audibility

Answer 21

For very short durations there is a 4-12 db decrease for very 10 fold increase in tone duration
The ear responds to the amount of energy in the signal but depends on power and time

Question 22

Describe Differential sensitivity

Answer 22

Sensitivity tells you what is the minimum change on frequency or intensity a person can detect

Question 23

Describe Weber Fraction

Answer 23

Weber found that people could just barely distinguish a 1 lb weight from 1.1 weight but it was impossible to distinguish between 100lb from 100.1 lb

People needed a 10lb increase to discriminate