perception 5 Flashcards
how do we localise sound?
binaural and monaural cues
what is azimuth?
left right plane
what is elevation?
up down plane
what are binaural cues?
comparison of signals in left/right ears
signal location of sound in azimuth
what are monaural cues?
work with one ear
localise the elevation and distance of sound
what are interaural time differences?
relative time at which a sound arrives at the two ears
what are interaural time differences affected by?
its location in azimuth
if straight ahead= distance to each ear is the same, no difference in time
if positioned to one side- reaches nearer ear first
what does the range of interaural time differences depend on?
speed of sound
distance between the two ears
what is the maximum interaural time difference for humans?
600us
what do interaural time differences require?
precise signalling of timing
what type of sounds are interaural time differences most useful for?
low frequency or abrupt onset sounds
what are interaural level differences?
relative sound pressure reaching two ears depends on location of sound in azimuth
why do interaural level differences impact a reduction in sound?
reduced sound for far ear due to head for high frequency sounds
where does binaural processing begin?
within the brainstem in the superior olive
what does the lateral superior olive contain?
neurons that are sensitive to ILDs
what does the medial superior olive contain?
neurons that are sensitive to ITDs
which binaural cue is best for low frequency sounds?
ITDs
which binaural cue is best for high frequency sounds?
ILDs
what are the limitations of binaural cues?
only provide ambiguous information about elevation
don’t tell us about distance
there are points which produce identical ITDs and ILDs= cone of confusion
what are monaural localisation cues- elevation?
when sound reflects off the external ear(pinnae), the relative intensity of different frequency sound waves change with elevation
this is affected by individual’s ear shapes
what are two monaural localisation cues for distance?
relative intensity
reverberation
what is relative intensity?
sound intensity decreases with distance
further distance= weaker amplitude
what is reverberation?
multiple reflections combine to produce a persistence of sound
sound reflecting off an object provides a cue for distance- as it alters the intensity and timing
what is the precedence effect?
similar sounds arriving in quick succession from different locations are localised according to the direction of the first sound
for a short delay, only a single sound perceived
what is auditory scene analysis?
need to segregate components of sound from different sources
need to group components coming from the same sound source
what is spectral grouping?
combining different frequency sound components that occur at the same time
-if a sound has a different harmony will be heard separately
-frequency components that change together group together
what is sequential grouping?
combining sequences of sound over time
what is auditory stream segregation?
organising sounds over time into separate perceptual events
what is sequential grouping: similarity of pitch?
sounds with similar pitch are often produced by the same source
increasing the frequency difference promotes stream segregation
what is sequential grouping: temporal proximity?
sounds that occur in rapid progression tend to be produced by the same source
increasing presentation rate promotes stream segregation
what is sequential grouping: similarity of timbre?
sound sources often have distinct tembre which provides a cue for stream segregation
what is sequential grouping: continuity?
sounds that stay constant or change smoothly are often produced by the same source
perceived as continuous even when interrupted by noise
what is phonemic restoration?
sequential grouping continuity can occur with speech as well as tones
