Hearing Flashcards
what is a sound
sound arises from the movement or vibration of an object
the movement squeezes air molecules together and pulls them apart and the pressure wave spreads outward towards the listener
how is pitch expressed?
in Hertz - the number of times a period is repeated every second so a sound with a period of 5ms has a frequency of 200Hz
what are some attributes of sounds
physical - amplitude, frequency, complexity
psychological - loudness, pitch, timbre
how is loudness defined
attribute of auditory sensation in terms of which sounds can be ordered on a scale from quiet to loud
how are decibels defined
scale for measuring intensity of one sound compared to another
how is pitch defined
attribute of auditory sensation in terms of which sounds can be ordered on a musical scale
how is timbre defined
attribute of auditory sensation in terms of which a listener can judge two sounds similarly presented and having the same loudness and pitch are disimilar
what is meant by ossicles
found in middle of ear
what is meant by stapedial reflex
automatic muscle contraction in middle of ear in response to loud sounds - muscle stiffen in ossicular chain to prevent damages to cochlea (inner ear)
whats the cochlea
principal job of cochlea is to act as a frequency analyser to convert energy at different frequencies into neural activity in different fibres of the auditory nerve
whats the basilar membrane
vibrates when the stapes move the fluid in the inner ear
what’s the intensity (loudness) of a tone coded by?
how quickly the fibres are discharging in the auditory nerve
describe the auditory nervous system
- cochlea acts as a frequency analyser
- superior olive analyses the location of sound
- inferior colliculus and medial geniculate analyse pitch
- primary auditory area in the cerebral cortex analyses higher order features of sounds including their spectral shape
what is frequency selectivity
ability to separate out sounds with different frequencies that occur at the same time
- determined by the properties of the basilar membrane
how do we know the basilar membrane is so selective?
we demonstrate this using a selective laser interferometry
- this measures the responsiveness of the basilar membrane in terms of speed of its movement and we can see that the basilar membrane is selective because the velocity of the membrane at the tested location depends on the frequency of the tone
what does frequency selectivity help with?
good for speech perception
- helps distinguish a vowel from another through distinguishing the formats
- the spectrum of sound starts at the larynx then the vocal chords
- the vowels in speech are characterised by patterns of peaks and valleys in their spectra
whats the bottom up effect on hearing
ascending to different connections
- cochlea -> cochlear nucleus -> superior olive -> inferior colliculus -> cortex
CCSIC
Describe the ganong effect as a top down effect on hearing
the ganong effect occurs when ambiguous speech is heard - listener categorises the sounds in a way that forms a real word (between g and k)
describe phenomene restoration as a top down approach on hearing
trick system into hearing a sound that is not there / long term language can create or retrieve illusions of sounds not present
describe the mcgurk effect as a top down effect on hearing
auditory illusion when someone looks like they’re saying BA we hear BA but they might be saying something else / visual information distorts auditory perception
Describe the sinewave speech as a top down effect on hearing
speech signal in which the formats of speech have been replaced with pure tones tracking the intensity modulations of those formats over time
why do we need to locate the sources of sounds
- location is important for information itself
- location of sound may orient visual attention
- sound location can separate sequences of sounds arising from different locations
Describe azimuth and elevation
- azimuth: left to right, 0 azimuth is straight ahead
- elevation: positive above 0 and negative below 0 up and down
Describe the minimum audible angle (MAA)
all suspended cylinders are speakers
minimum angle that allows you to carry out experiments to see how far we can hear sound
- when MAA is at 0-1 degree angle, ppts can tell where sounds are at low frequency
- as angle increased, the frequency increases and decreases with peak at 14 degree angle
