Psychoacoustics for Audiologists Flashcards

Terms Definitions
What is a psychometric function?
a graph indicating percent correct as a function of stimulus being changed from this graph you can get % level for threshold that you want
The property of the ear to sum signal energy over time is ?
Temporal Integration
Measuring the limits of temporal sensitivity is done with what type of procedures?
Gap detection procedures:compare 2 stim. one with temporal gap &one with no gap.vary the gap duration to find the smallest detectable gap
Define masking
the shift (change) in the threshold of one sound due to the presence of another interfering sound.-how one or more sounds interfere with the perceptio of the sound you want to listen to
If the sound you want to hear is made less audible due to the presence of another sound we say .....
the signal is being masked
Why do we measure masking?
It is an effective means for studying frequency analysis
What is frequency analysis?
the ability of the ear to resolve the individual sinusoidal components of a complex sound.frequency selectivityfrequency selectivity
When measuring masking what is the 1st thing we need to know abou the audibility of the signal?
How well the listener can hear the signal when noise is not present = quiet threshold QAT
High frequency maskers are effective only over?
relatively narrow frequency range in the vicinity of the masker frequency
Low frequency maskers are effective over...
a wide range of frequencies
Masking PatternsStrongest masking occurs in the vicinity of ___ ____.Masking increases as ____ of masker is raised.Greatest masking occurs for tones____ than masker freq very little masking _____
Masker Frequencyintensity Higher (upward spread of masking)Below
What frequencies serve as best maskers?
frequencies near the signal frequency
The relative difference ratio is called?
The Weber Fraction
What are difference limens (DL) or JNDs?
Term used to describe sensitivity to changes in:- frequency- intensity- durationsmallest change in one of these parameters that can be detected
What is "dynamic range"
The useable range of hearing.- the difference between the threshold of discomfort and - threshold of hearing
Speech intelligibility as a function of SNR in anechoic &reverberant environment, performance is _____ in an AN environment when speech an noise are _____.Performance improves with ___SNR in the RV environment
better ...... separatedincreasing 'Signal is significantly > in the anechoic than in reverberent environments
Signals are generally detected more easily in ___ conditions than ___ or ____
If we measure threshold for a tone in noise in both ears (same S&N) then remove the signal from one ear what happens?
the threshold will improve
This improvement in threshold when the signal is removed is called
Masking level difference or release from masking
JNDs tend to (increase/decrease) as SL increases up to about __dB then slight (increase/decrease) up to 80dB?
decrease 30dBdecrease or flat
Puretones cannot be localized or lateralized at ___ frequencies based on ITD but can localize/lateralize with high frequency noise
high frequencyit is believed that listeners obtain informatio from the envelop of the stimulus not the microstructure
When localization is measured IA time and intensity differences can't be ___ ___. What is a measure that allows us to control these differences?
separated outlateralization-can control these differences using earphones- signals are turned on & off- subject often perceives as a movement of image inside head
What is echo threshold?
the delay at which fusion first breaks down & 2 separate sounds are heard
Precedence requires sounds with ___?
sharp transients
The biggest errors in localization judgment are from what azimuth?
Behind the head
Interaural intensity differences IIDs result from what 2 aspects of sound?
Proximity to the sound source (source is closer to 1 ear than the other)head shadow effect (major contributor)
Why does the head shadow effect produce big IIDs?
If the wavelength of the stimulus is equal or the higher the frequency the shorter the wavelenght --> the greater the sound shadow
Interaural Time differences (ITDs) occur at all frequencies but at high frequencies (> 1500Hz) they...
do not provide good cues for localizingat high frequ, time differences are confusing to the ear .. they happen too quickly
The largest interaural time difference occurs at what azimuth?
90 degrees
The two basic cues for localization are?
Interaural time differences (ITD)Interaural Intensity Differences
What are heterophasic stimuli?
uncorrelated stimuli presented to the 2 ears
Monotic or monaural stimuli ?
stimulus presented to only one ear
Dichotic stimuli?
Different stimulus presented to each ear
Diotic /homophasic stimuli?
same stimuli to both ears
ITDs are determined by
the difference in the distance to each ear from the source
What does the Cocktail Party effect refer to ?
our ability to follow what one person is saying when one or more people are talking at the same time.we are able to use binaural cues... binaural unmasking
Can we localize with only one ear?
Pinna cues or monaural spectral cues at high frequencies introduced by the pinna are important for the perception of elevation, front to back distinctions and monaural localizationLow freq cues associated with vertical localization
What is MAA
Minimum audible angle = smallest angular separation (in degrees) between 2 loudspeakers that a listener can just detect
What is the Precedent Effect?
The law of the 1st wavefront- information about the sound source location is contained in the 1st sound wave reaching the ears, even though in all reverberant environments there is more than one sound wave reaching the ears
Sounds are louder when we listen with 2 ears why?
binaural summation2:1 advantage
What is scaling?
A direct method where the listener is asked directly about the stimulus. - listener establishes a relationship between a standard & comparison stimulus-listener specifies a perceptual continum corresponding to a physical continuum.
4 different measurement scales?
What is ratio estimation?
Subject gives their subjective magnitude of a comparison stimulus as a ratio of the standard ex. 1/2 as loud or 2 times as loud
What is ratio production?
Subject adjusts comparison to sound like a particular fraction of the standard
What is Magnitude Estimation?
subject assigns numbers to a stimulus to describe the magnitude ex.on a scale of 1-100 judge loudness of different sounds
What is magnitude production?
subject given numbers and adjusts the stimulus to have a particular loudness ex.50% , 80%
What is cross modality matching
express the perceived magnitude estimation and production in terms of a different sensory modality like a linesoft______________ loud
What is psychoacoustics?
a branch of psychophysics concerned with the perception of sound in relation to the physical stimulus
2 general approaches to studying the relationship between psychological & physical aspects of a stimulus are?
Discrimination-same or different, indirect means of determining what a subject can respond toScaling procedures - Ask the subject directly about the stimuli (louder or softer)
Two general classes of methodology?
Classical methodsignal detection theory procedures
Three classical methods ?
Method of limits-affected by response bias, habituationmethod of adjustment- listener may change criteria for responsemethod of constant stimuli- takes a long time
What isSignal Detection Theory
The theory provides a tool to use to separate out the effects of bias and sensitivity in psychophysical measurement.
2 parts of signal detection theory
Decision theory- rules that are used in making the decision of signal present or notDistribution Theory - ROC analysis
Assumptions of Signal Det Theory?
There is always some noise present- internal/externalall stimulation is measurable along a continuum, is the SN or NDecisions are based on both sensitivity & response bias
4 possible outcomes of signal detection are
hit, miss, correct rejection, false alarm
The effect of frequency on the human ear has a ____ basis
logarithmic basis
the 12 tone musical scale is an example which evolved due to the way tones are ?
perceivedGoing 12 notes higher (an octave) is the same as doubling the frequency
Raw frequency resolution of the ear is best judged in terms of ____ or in ____ which is ____ of a ______
semitones cents1/100 of a semitone
Research has shown that infants can discriminate among vowel in their native language by what age?Consonants by what age?
6 mos11-12 months
What is temporal integration
the ability of the ear to sum energy over timethe ear is not a constant energy detector for sounds
The ear integrates energy over time up to about
500 msecfurther increases in duration ar not associated with decrease in threshold
typical temporal cues occur how?
binaurally-in the presence of reverberation -between signals of different intensity & frequency
When the frequency of the lead & trail are the same GDD is
comparable across age groups
When the frequency of the lead & trail differ the GDD
varies with age-young group GDD increases a little larger freq difference especially when trail is below leadFor middle age- GDD increases in the same way but more-The older group shows the largest effect of lead/trail freq difference on GDD and greater variability overall
There is a critical band of frequencies around a signal that we need in order to ?
mask a signal most efficiently
Once the critical band is reached if we make the masker wider ...
it will not provide any additional masking
The filter in the ear referred to as critical band implies
that the filter in the ear only allows certain frequencies to pass through
Masking patterns are sometimes called
Masking audiograms
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