CSD 303 Unit Two

Human Audibility Curve

the graphic representation of auditory sensitivity across frequencies

Psychophysical Methods

the methods applied in order to find auditory sensitivity

Temporal Integration (Summation)

the change in sensitivity with duration- our sensitivity improves as the duration of a stimulus is lengthened from the shortest duration that produces a perception of tonality; i.e 10 ms for a wide range of pure tones, to about 300 ms

Define threshold and identify the variables that affect minimum auditory sensitivity

threshold is the lowest signal intensity at which the signal can be identified 50% of the time
variables: ?

Describe the effect of stimulus duration on auditory testing

the absolute threshold reaches its lowest point as a duration of sound is extended - stays at the lowest point if duration is extended out any further

Identify the three primary psychophysical methods used determine threshold

1) method of limits- the changing of one parameter of the auditory stimulus (intensity in this case), by the person performing the test, with the person being tested asked to indicate in some way when he or she detects the stimulus
2) method of adjustment- the subject adjusts the parameters (the intensity level in this case) to the point where it is barely audible
3) method of constant stimuli- uses a technique called the "two-alternative-forced-choice procedure" where the listener makes a choice from two options, yes or no

Temporal Integration

auditory system's ability to make use of and integrate signal information over time

Temporal Patterning

the auditory system's ability to discern pattern differences in auditory signals\

Temporal Resolution

the ability to detect rapid changes in an auditory signal over time

Describe temporal processing skills including temporal integration, temporal resolution, temporal patterning

temporal integration is the idea that as a sound gets longer, the absolute threshold will go down, temporal resolution refers to how sensitive you are to the way a sound varies over time, temporal patterning determines how you recognize patterns in auditory signals

Equal Loudness Contours

what results on a graph if we were to present 1 kHz pure tone at one sound pressure level, then ask listeners to determine a level at which other frequencies of pure tones sound equally loud, then repeat this process with other SPLs of our 1 kHz

Loudness

the subjective perception of the intensity of a sound

Magnitude Estimation

a technique standardly applied in psychophysics to measure judgements of sensory stimuli

Magnitude Production

a scale which requires participants to adjust a stimulus to match the magnitude which they are shown on a piece of card and which coreepsonds to the scale

Mel Scale

an interval scale that quantifies the difference in pitch; 2000 mels is equivalent to a pitch that is twice that of 1000 mels

Phon

the level in dB of the standard 1 kHz tone against which the subjective loudness of other frequencies is matched

Pitch

the psychological perception of the physical property of frequency

Sone

a unit of measurement used for a loudness scale

Describe the perceptual concepts of loudness and pitch and relate them to the physical measurements of intensity and frequency

loudness and intensity are directly related; pitch and frequency are directly related

Identify the differences between a phon and a sone as units of measurement

phon: phon scale is an example of an ordinal scale in that it shows an order of magnitude but makes no attempt to quantity the actual difference in magnitude sone: sone scale is an example of an interval scale in that we can determine that a sound of 4 sones is half as loud as a sound of 8 sones; the actual difference in magnitude can be specified

Staircase Method

a modern and more efficient variation on the method of limits: descending methods of limit runs start well above a listener threshold and ascending runs start well below it. So a lot of time is spent testing at intensities that are a long way from the true threshold, which is inefficient

Weighting

an adjustment applied to sound measurement to reflect how a noise is perceived by the human ear.

Backward Masking

when the signal is presented and terminated just before the presentation of the masker.

Band-pass Filter

the combination of high-pass and low-pass filters, it allows frequencies between two points to pass through

Critical Band

range of frequencies surrounding a given stimulus frequency that contribute to the masking of that frequency. when a ton is just masked by a noise, energy falling within the critical band equals that of the tone.

Forward Masking

the masker is presented and terminated just before the signal is presented.

High-pass Filter

allows only frequencies above a certain frequency to pass through.

Low-pass Filter

allows only frequencies below a certain point to pass through.

Narrowband Noise

a noise that is restricted in its frequency range: to produce a narrowband noise, we employ an electric or digital filter, which allows only the desired frequencies to pass through it.

Wideband Noise

an auditory stimulus with equal amplitude of all frequency components. it produces a more generalized masking pattern than narrow bands of noise for broader-band stimuli.

Masking

a process in which the threshold one of sound is raised by the presentation of another sound- involves the introduction of a sound to an ear (the masker) to preclude a person from hearing another sound (the signal) in the ear

Describe the concept of the upward spread of masking when pure tones mask other pure tones

when a masking sound gets turned up, its masking effect with spread into the higher frequencies more rapidly than it will the lower frequencies

Identify the concept of critical band and its application to masking

critical bands protect the ears from masking from any frequencies outside the filter's band pass

Identify a low-pass, high-pass, and band-pass filter and explain the function of each filter type

low-pass filters allows lower frequencies to pass through, high-pass filters allow high frequencies to pass through. the band-pass lets a band of frequencies pass through and attenuates frerquencies below and above that band. All of these are considered critical bands

Just Noticeable Difference (JND)

another name for difference threshold

Weber's Law (Weber-Fechner Law)

For every sensation, the just barely detectable amount of change in a stimulus (JND) will be some constant fraction of the stimuli thats already present

Explain the difference between absolute thresholds and difference limens

absolute threshold is the minimum amount of stimulation required to trigger a reaction or produce a sensation; difference limen is the smallest difference between two stimuli than can be accurately detected