Chapter 7 Flashcards
amplitude
intensity of a sound wave
loudness
related to amplitude; a sensation
frequency
number of compressions/second measured in Hz, most adults hear from 15-20,000 Hz
Pitch
related aspect of perception
pinna
outer ear structure of flesh and cartilage attached to the side of the head; alters reflections of sound waves to help us locate the source of a sound
tympanic membrane
ear drum, in the middle ear, vibrates with same frequency as the sound wave that strikes it; connected to three tiny bones (hammer, anvil and stirrup or malleus, incus and staples) that transmit vibrations to the oval window
oval window
membrane of the inner ear
hair cells
auditory receptors; lie between the basilar membrane of the cochlea on one side and the tectorial membrane on the other
cochlea
snail shaped structure of the inner ear that contains 3 long fluid filled tunnels: the scala vestibuli, scala media, and scala tympani
place theory
the basilar membrane resembles strings of a piano in that each area along the membrane is tuned to a specific frequency; each frequency activates hair cells at only one place along basilar membrane and nervous system distinguishes among frequencies based on which neurons respond; downfall: basilar membrane too tightly packed for this
frequency theory
basilar membrane vibrates in synchrony with a sound causing auditory nerve axons to produce action potentials at the same frequency (i.e. 50 Hz = 50 action potentials); downfall: refractory period is typically 1/1,000 second, so maximum firing rate of a neuron is about 100 Hz
current theory
modification of place and frequency; for low (under 100 Hz) - frequency theory; soft sounds activate fewer neurons than loud; volley theory up to 4000 Hz; place theory 4000+
volley theory
the auditory nerve as a whole produced volleys of impulses for sounds up to about 4000/sec
Primary auditory cortex (A1)
superior temporal cortex
conductive/middle ear deafness
deafness as a result of diseases, infections or tumourous bone growth that can prevent the middle ear from transmitting sound waves properly to the cochlea; can be temporary, can be corrected; normal cochlea and auditory nerve, and own voice is audible
nerve deafness/inner ear deafness
results from damage to the cochlea, the hair cells, or auditory nerve; can occur in any degree and may be confined to any part of the cochlea in which case someone hears certain frequencies and not others; can be inherited or developed (i.e. exposure to rubella, syph, toxins in womb, inadequate oxygen during birth, deficient thyroid, diseases incl. MS and meningitis, childhood reactions to certain drugs, loud noise exposure