perceptual

the (audible) energy of vibrating particles 

# cycles/second in Hertz (Hz).  A 1000 Hz tone goes through 1000 cycles every second

Magnitude of displacement from equilibrium 

• the relative timing of the sound wave.  
• When does it start relative to another sound wave?

the perceptual correlate of frequency (how we perceive it)

amplitude of sound pressure level being perceived

20-20,000 Hz

sound --> outer ear --> middle ear --> inner ear --> brain

pinna (external, visible portion) and the ear canal (external auditory meatus)

collects and funnels sounds into the ear

boosts the high frequencies by about 5dB

helps with sound localization

boosts frequencies around 2500-3500 Hz by about 15dB

eardrum (tympanic membrane)

3 ossicles (bones): malleus (hammer), incus, stapes (stirrup)

vestibule semicircular canals

cochlea

Stapes vibrates --> sets fluids of the cochlea into motion --> moves the hair cells back and forth --> causes an electrochemical change that converts the signal into neural impulses (action potentials) in the auditory nerve

carries info (still organzied tonotopically) to the brainstem and beyond

located in the temporal lobe in the sylvian fissure (heschl's gyrus) of the superior surface of the temporal lobe

cell organization is similar to that of the visual system

The neuron fires at the same frequency as the incoming sound

The frequency of the incoming sound stimulates a particular point on the basilar membrane, and the neurons connected to that frequency region fire