# feb7

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```					Alexis Harvey
Psyc 375
February 7, 2012

Detection: thresholds
 Audibility
 Minimal audible pressure (MAP)
 Minimal audible field (MAF)
 Dynamic Range
 The stuff we care to listen to. Below the pain threshold but above the
audibility threshold.

Summation of Energy
 Temporal
 Hughes' Law - gives prediction or compensation for integration over
time.
 Combining information over time
 Across Frequency
 Critical band = processing unit = 1/3 octave wide
 Combine frequency over a certain range.
 Anything within a certain frequency range will be treated (the 1/3 of
an octave)
 A frequency increases, critical band gets wider
 Across ears
 binaural threshold = 1/2 of monaural

 Interferes with perception of supra-threshold sound
 Most interfence is going to happen when the mask and the target are
close together in frequency
 Upper spread of masking means more interference in target in one
direction. If the mask is below the frequency of the target, you are
more like to get interference than when it is higher.
 Psychophysical tuning curves: produced om tonal masking
experiments. Possible to get behavioral data that maps perfectly to
physiological data

Noise Making
 Signal/Noise (S/N) Ratio
 Positive is good use so signal is louder than noise
 How we decide how loud something such as a warning alarm should
be.
 Critical Band
   The range over which we coud have interference.
   Critical band size
   Equivalent rectangular bandwidth (ERB) filter

1.        Simultaneous
2.        Forward: M --> T ( ISI <300 ms)
3.        Backward: T --> M (<25-40 ms)
4.        Central: T (ear 1) + M (ear 2)
         Maks needs to me at Lear 30 to 50 decibels less than
target.

Pitch
 Pitch Scales --> log frequency scales, meaning as we increase frequency, you
will need a bigger change in frequency to hear a change in pitch
 Music Scale
 Some factors influencing pitch
 Level (e.g., Doppler Effect)
 Duration - tone pip vs second long tone, without repetition there is no
pitch.

Place Theory
 = look at this slide online
 Problems
 Missing fundamental - not in all instances is pitch going to change
when fundamental is removed
 Broad pattern of variation below 500 Hz - makes it hard to place
 Modern Alternatives
 Periodicity Pitch vs. Virtual Pitch
 Virtual pitch is experiencing pitch form something what should not
produce it. It is random, there is no repetition.

Frequency/Temporal Theory
 = firing pattern across neurons. Volley Principle

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