Hearing Flashcards
What was studied in relation to the auditory system?
The outer, middle and Inner ear The cochlea and corti Auditory nerve fibres Superior Olive Inferior Collicus
What was studied in relation to sound localisation?
Inter aural time difference
Inter aural level difference
Pinna and head cues
What was studied in relation to Auditory distance perception?
Relative intensity
Spectral composition
Direct vs reverberant energy
What does hearing a sound suggest?
You have detected a change In Air pressure
What is the frequency of sound and what is it measured in?
The number of times per second that a wave repeated (changes in pitch)
Hertz
What is the range of human hearing in hertz?
20-20,000 Hz
What was studied in relation to sound?
The auditory system Frequency and Amplitude Sound Localisation Auditory Distance perception Scene analysis, continuity and restoration Categorical perception
What is meant by amplitude in relation to sound and what is it measured in?
The intensity or magnitude of the sound wave (loudness)
Decibels (dB)
What is the range of decibels detected by humans?
0-140 (painful)
What is a spectra?
The sound wave pattern and shape
What is timbre?
The quality of sounds conveyed through harmonics
What are the parts in the outer ear (external ear canal)?
Pinna
External Auditory Canal
Ear Lobe
What are the parts of the Middle ear?
Malleus Eardrum (tympanic membrane) Incus Stapes Oval window
What are the parts of the Inner ear?
Semi- circular canals (labyrinth)
Auditory nerve
Cochlear
Eustachian tube
What is the path of sound through the ear?
Ear canal > ear drum > vibration > malleus moves > anvil (incus) moves > stapes moves > oval window distortion > fluid pushed into vestibular canal of cochlear
Once fluid starts to move in the cochlear, what is the path?
Movement in the tympanic canal > distortion of the basilar membrane (separates vestibular canal and cochlear duct) > organs of corti
What happens after the basilar membrane separates the vestibular canal and the cochlear duct?
The organ of corti presses against the tectorial membrane
What is the force called that is formed from the organ of corti pressing against the tectorial membrane?
Shearing force
What does the shearing force do?
Bends the stereocilia in different directions which sends signals to the auditory nerve fibres to then send to the brain
How is frequency coded in the cochlear?
Lower frequencies cause displacement near the thinner part of the basilar membrane (apex)
Higher frequencies cause displacement closer to the oval window (thicker and wider)
Explain top-down hearing.
Auditory nerve fibres although they send messages to the brain (bottom-up)
They also send messages from the brain to the ear’s outer hair cells to tune in to particular frequencies
Where do auditory nerve fibres first synapse?
In the brain stem
What parts of the brain are involved in binaural integration?
Cochlear nuclei
Superior olive
After auditory nerve fibres synapse in the brain stem, what parts of the brain are involved in further processing?
Inferior Colliculus (second stage) Thalamus (integration of audio & visual reflexes) Auditory Cortex in the Temporal Lobe (higher processing)
How is the auditory cortex organised?
Tonotpically (different frequencies mapped onto different areas)
Which parts of the auditory cortex process the more complex stimuli?
The surrounding belt and the parabelt
What are the 3 things that help us tell where sound is coming from?
Interaural time difference
Interaural level difference
Head and pinna cues
What is Interaural time difference?
The difference in the times the same sound is processed by the medial superior olive (brain stem) depending on what angle it comes from and which ear it enters first
What is Interaural level difference?
the difference in intensity between the sound arriving at one ear versus the other (better for low frequency sounds because they are not as obstructed)
What are head an pinna cues?
the placement of your head and the shape (pinna) of your outer ear
To get a good grasp on the perception of auditory distance we need to process:
The relative intensity of the sound
The spectral composition
The relative amounts of direct vs. reverberant energy
To detect relative frequency we need to have:
An expectation of how loud a sound should be
better detected if the sound is moving
To detect spectral composition clues include:
Far away sounds = more muffled if higher in frequency because more easily absorbed
eg. thunder close by is a crack but far away is a rumble
What is the difference between direct and reverberant energy?
direct = coming from the source reverberant = bounced off from surfaces in the environment (generally sounds from further away- different quality of sound)
What is spatial segregation?
sounds coming from the same location are probably from the same source
What is grouping by onset?
sounds that start together tend to be perceived as from the same source
What is grouping by frequency?
Sounds similar in frequency are probably from the same source.
What is grouping by timbre?
sounds from the same timbre typically come from the same source
How can you group sounds?
By: Spatial segregation Onset Frequency Timbre
What does occluded mean?
hidden behind or interrupted
What is it called when our auditory system fills in the gaps in sound streams so that we perceive the sound as continuous?
Restoration
Which sound more continuous? Sounds that are occluded or sounds that have silences?
sounds that are interrupted with other sounds
What is amusia?
not being able to perceive the differences in melodies
How early can babies differentiate between a familiar vs unfamiliar melody?
2 months
4 months they prefer consonant melodies (not dissonant)
What are 3 things that have been suggested for the reason that we have developed music perception?
sexual attraction
group bonding
side effect of language evolution
What are formants?
bands of acoustic energy on a spectrogram caused by a particular resonance in the vocal tract (e.g I miss (higher) you (lower) )
What is coarticulation?
the production of one speech sound overlaps with the next (eg. Bahhh has a different B sound do Boo and Bee)
What is the lack of invariance?
the fact that the articulation of sounds is not consistent and changes depending on the surrounding sounds (surrounding letters) eg. DI and DA
What does the categorical perception of speech sounds refer to?
The fact that we place sounds in categories however they are actually on a continuum. Ba and Da are not two distinct sounds, they are just placed at different places with many interpretations of the sounds between them along the continuum.
Why do some adults not hear sounds from a different culture?
Because they are not categorised in their native language eg. B vs V in spanish are not separate sounds (or letters) they are simply placed on a continuum of long V and short V
