Hearing Threshold and Sensitivity Flashcards
Define Psychoacoustics
Psychoacoustics is defined as auditory perception and senstive to frequency amplitude phase and duration
What is detection
How minimal a stimulus you can perceive
What is recognition
Sense of having heard a stimulus before
What is identification
Being able to identify a stimulus
What is discrimination
Ability to tell 2 or more stimuli apart
What is the threshold of audibility
the smallest level required for detection to the frequency of the tone
What are the perceptual correlates of pitch, intensity, phase and time
Frequency-pitch
intensity- loudness
time- duration
How are sensitivity and threshold related
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
What is the minimum audibility curve
The auditory response area. The plot of threshold detection levels as a function of frequency
What is the minimum audibility field
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
What is Minimum audible pressure
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
How are MAP and MAF different
MAF is done without headphones in a free environment while MAP is done with
How do MAF and MAP curves relate in terms of threshold pressure
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
What is the reference equivalent threshold sound pressure level; and how is it measured
RETSPLS- there are different types of earphones and different types of couplers
What is a circum-aural earphone
Fits complexity over and around pinna and calibrated using artificial ear
What is supraural earphones
Fits over (against) pinna and calibrated to 6cc coupler
What is intra aural (insert) headphones-
Inserted earphones into outer ear canal and calibrated with occuluded ear stimulato
Define dB hearing level
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
What is an audiogram
When the detection of tones of different frequencies is plotted in dB HL instead of dB SPL
What are the effects of age, sex and noise on exposure of hearing thresholds
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
What are the duration effects to threshold of audibility
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
Describe Differential sensitivity
Sensitivity tells you what is the minimum change on frequency or intensity a person can detect
Describe Weber Fraction
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
