Audition Part 1 Flashcards
what are the two steps of sound & what do they mean
compression = pushing air molecules together rarefraction = then stretches them apart & repeat..
what is a pure tone?
a tone with one frequency
what is a wave of a pure tone called
sine wave
a graph of pressure changes over time is called a…
waveform
what are the three critical features or parameters of waves
- frequency: how many full waves in a second (in Hz), corresponds to pitch of the sound - pitch
- amplitude: how high is the wave? (deciBels, or dB), corresponds to loudness of the sound - loudness
- phase: how far through the wave are we (degrees) - timbre
what are sound waves?
linear e.g. they add together logically (sum the values at each point in time)
what are natural sounds a collection of?
simple sine waves added together
the waveform of any sound can be expressed as what?
a sum of sine waves with different freqs, amps & phases
what is fourier analysis
when you decompose a complex sound into its component frequencies, amplitude & phase
what happens when you add two soundwaves
the frequency stays the same but the amplitude gets higher
what happens when you add sounds of different frequencies
they form a complex wave
discuss a complex wave form
- made up of sounds of different frequencies
- wave forms are periodic (they repeat) the x-axis (time) gives little info
what is a spectrum
when you re-plot the wave-form graph as amplitude vs frequency rather than amplitude v time
what is a fundamental
the component with the lowest frequency
what does the fundamental frequency give
the pitch
what gives the characteristic sound in instruments that have the same frequency/pitch
the characteristic overtones
what are the three parts to the ear
- outer ear
- middle ear
- inner ear
what composes the outer ear
- pinna
- meatus
what composes the middle ear
- ossicles
- tympanic membrane (ear drum)
what composes the inner ear
- cochlea
- baslar membrane
what does the outer ear do
pinna: the flexible flap on outside of the ear
focuses sound waves into the ear canal (meatus)
shape and size of outer ear have the effect of amplifying medium sound frequencies
what does the middle ear do
the small bones (ossicles) in the middle ear transmit sound energy from the eardrum to the oval window in the ear
discuss the inner ear
containes a small coiled tube (cochlea) filled with fluid
- oval window & other window help to make the fluid vibrate
- has three parts
- transfers sound energy into chemical energy that is used by the nerves
how do the middle ear & the inner ear work together
the middle ear vibrates the inner ear’s fluid & transmits this vibrating energy into the inner ear
what is the organ of Corti (inner hair cells)
receptor organ located in the cohlea has epithelial cells and allows for the transduction of auditorty signals into nerve impulses action potential
how many inner hairs do we have & where do they protrude from
3500, basilar membrane
how many nerve fibres do we have
50,000
the base of the baslar membrane is
thin & stiff & hears high frequency
the apex of the baslar membrane is
wide & floppy & hears low frequency
