Hearing L1 Flashcards
what is pitch?
frequency
T or F
We are relatively insensitive to changes in the phase of a sound and thus there is no subjective correlate for phase
T
what is phase of a sound
Two sound waves of the same frequency that are perfectly aligned have a phase difference of 0 and are said to be “in phase.”
The speed of sound (for these lectures = ____ m/s in air)
The speed of sound (for these lectures = 340 m/s in air)
describe the decibel scale
0 dB means that the sound has the same pressure as the reference signal (Log 1= 0)
- It is not possible to express a level of zero sound in dB (Log 0 = - infinity)
- Negative values of dB do not mean negative sound - the specified sound is simply less than the reference
what are low and high pass filters?
& band pass filters
A filter that passes only frequencies below a designated ‘corner’, or cut-off frequency, while attenuating higher frequencies is called low-pass (LP). Conversely a high-pass (HP) filter attenuates frequencies below the corner frequency. A band-pass (BP) filter (Fig. 3c) only passes frequencies within a restricted range or bandwidth whereas a band-stop (reject) filter only passes frequencies outside of a restricted bandwidth.
why is the length of the external auditory meatus important?
The external auditory meatus (EAM) or ear canal acts as an open-ended tube and has resonant peaks that are predictable from knowing its length (2-3 cm in man). Figure 5 shows the gain measured in a real ear (solid line) and the gain calculated assuming an open tube of length 2.3 cm.
This gain coincides with the frequencies most important to human speech.
Explain how the pinna can modify sounds in a space dependant manner
the pinna modifies the specra.
first notich is a good cue for elevation of the noise
what happens if we lose the pinna? or alter it?
shows its very plastic
functions of the inner ear?
(i) impedance matching between air and cochlear fluids,
(ii) protection from loud sounds, including own vocalisations and
(iii) anti- masking of high frequency sounds by low frequency sounds - particularly at high sound levels.
function of the middle ear muscles?
The middle ear muscles (MEM) serve to dampen the vibrations of the ossicles thereby reducing the acoustic signal that reaches the ears.
giev some properties of the middle ear muscles
- They are the smallest skeletal muscles in the human body
- They contract about 100 ms after exposure to a loud sound and before a person vocalises.
- They are absent in frogs that do not vocalise
- They attenuate low frequencies more than high
- The MEM reflex is activated by sounds 80 - 90 dB above a person’s hearing threshold
The tensor tympani muscle is connected to
……
whereas the stapedius is connected to t/……..
The tensor tympani muscle is connected to the neck of the malleus whereas the stapedius is connected to the neck of the stapes
T or F
n humans, only the stapedius is active when exposed to loud sounds
T
is the MEM only seen in one ear if only that ear is exposed to the sound?
no - BOTH ears/
cross pathway
The audiogram in Figure 11 shows the hearing of a person with an inactive stapedius who had been exposed to loud sounds for a prolonged period.
The other line shows the hearing level of a person in a similar noisy environment but who has an intact stapedius.
describe where along the cochear low and high pitched sounds vibrate?
The cochlear partition is narrower and stiffer near its base than its apical end and therefore vibrates maximally for high frequency sounds near the base and maximally for low frequency sounds near its apex (
how are frequencies mapped out along the length of the cochlea
The frequencies are said to be mapped out tonotopically along its length with equal increments in distance corresponding to equal increments in logarithmic frequency
