Auditory Spatial Processing Lecture Flashcards
(29 cards)
What is a good starting assumption of the perceptual system
It wants to give you the most accurate information about your surrounding by combining information from all senses
Applications for sound processing
Effects of blindness and partial visual loss
Hearing loss and aging
Designing hearing aids
What are allocentric representations of sounds?
Where the sound is in relation to other sounds
What are egocentric representations of sound?
Where the sound it in relation to me
What makes internal representations inaccurate?
Limited information e.g dark and noisy
Spatial biases
Conflicting cues
Difficult to track multiple moving objects in space
How does spatial perception rely on cues?
Various location cues need to be available to be combined to give accurate perception of surroundings
Cues vary on environment
What does it mean to be binaural?
Listen with two ears
What is localisation in regards to auditory spatial processing?
Judging sound source location in terms of left-right direction distance or elevation
What are azimuth cues?
Interstitial time difference and interstitial level differences
Cues for locating sounds
Discrimination in sounds
Discrimination involved more than one sound
How can the smallest values for discriminating ITD and ILD be measured?
Using headphones with a set reference
Interaural time difference (ITD) cues for azimuth location
Takes approx 0.6 ms for sound to travel across the head
Inter aural level difference cues for azimuth localisation
Low frequency sounds are not substantially attenuated by the head so ILD cues are better for localising high frequency sounds
ITD and ILD discrimination threshold
A change in ITD is detectable at 900 hz, cannot be detected above 1500 hz
IDL threshold smallest for frontal sounds
What is the duplex theory?
The perceived azimuth of low frequency sounds dominated by the ITD. For high frequency stimuli, the auditory system weights the ILD more when determine the azimuth
When is sound localisation poorest?
Where neither ITD or ILD cues work well, around 1500 Hz
Auditory level as a cue for distance
Lower level cues are perceived as further away from
Sound level falls by 6 for each doubling of the source distance
Reverberation for auditory distance cues
Reverberant sounds are judgedas more distant
Depends on absorption by the surrounding walls floor and ceiling
Auditory elevation cues
Conviction of the outer ear result in direction dependent shaping of the spectrum of sound
The head related transfer function
How the ear received sound from a spatial location
Dealing with ambiguity
Using spectrum cues provided by peaks and dips in the sound spectrum for each ear
How can localisation abilities be tested?
Virtualisation techniques using headphones
Have precise control and multimodal experiments
using headphones to assess localisation
Headphones remove pinna cues, making the sound internalised. This is overcome using headphones related transfer function
What is the precedence effect?
When two identical versions of a sound are heard with a brief delay between, a single sound is heard. Spatial position determined by the first sound
