Perception 4 Flashcards
What is sound and why does it occur?
Sound is referred to as what we experience when we hear
It is due to pressure changes that occur within the air, caused by vibration of an object
A pure tone is…
when changes in pressure can be defined as a sine wave
Amplitude is…
Height of the sound wave
Related to loudness perception
Frequency is…
How many times a sound wave will repeat itself within a second (Hz)
Related to pitch perception
A higher frequency is a shorter wavelength
What parts make up the outer ear?
-Pinnae
-Auditory canal
-Tympanic membrane (eardrum)
The pinnae is…
The external parts of the ear that is visible
The auditory canal is…
The main tube that protects the middle ear
The tympanic membrane (eardrum)…
Membrane separating the outer ear and middle ear, it vibrates due to sound waves causing pressure either side of the eardrum
Large amplitude = large vibrations
High frequency = fast vibrations
What parts make up the middle ear and what do they do?
Ossicles (smallest bones in body):
-Malleus (hammer)
-Incus (anvil)
-Stapes (stirrup)
These bones enhance the vibrations that come from the eardrum and send them to the inner ear
What parts make up the inner ear?
-Cochlea
-Oval window
The cochlea…
is a liquid filled organ that is snail-like, and consists of 3 parallel canals; vestibular, middle and tympanic
Describe auditory transduction
Caused by vibration of basilar membrane
When the hair cells within the Organ of Corti become bent, triggers a response which is then sent to the optic nerve
If there’s too much noise then this can damage the hair cells as they as they are extremely sensitive
What is a rate code and what does it relate to?
Related to loudness perception
It’s a coding method that is used to process sound waves by looking at how many spikes there are in a neutron in a given period of time
What are the key points of loudness perception?
-Higher amplitude = faster the auditory nerve fibres respond
-For a sound to be perceived as twice as loud as it’s original, the amplitude has to be increased by 10dB
What are the key points for pitch perception?
-Relies on frequency
-The lowest frequency a human can hear is 20Hz and the highest is 20,000Hz
-Pitch tends to be determined by what the fundamental frequency is e.g. instruments may have the same fundamental frequency (play the same note) but they differ in harmonics (sound slightly different)
