Can you ear me?? Hearing & the ear
description
Transcript of Can you ear me?? Hearing & the ear
![Page 1: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/1.jpg)
A brief discussion
CHAPTER 7 – Measured Tones
![Page 2: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/2.jpg)
ear
![Page 3: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/3.jpg)
![Page 4: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/4.jpg)
![Page 5: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/5.jpg)
WHY do we need to hearhear?
WHY did earsears evolve in most (not all) species??
![Page 6: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/6.jpg)
Must hang on the head in a place where it usually won’t be tightly covered.iPods etc. excluded
It should be very sexy. It can’t be too heavy. It should be sensitive. It should be able to sense direction of
the sound’s origin. (Why?) It should be able to distinguish a
range of frequencies. (Why?)
![Page 7: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/7.jpg)
A sound “collector” to channel as much of the sound as possible to the actual collector.
![Page 8: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/8.jpg)
![Page 9: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/9.jpg)
A sensor that collects the sound and converts it into something that moves. A membrane at the end of the collector would
work because it will move in response to the pressure changes in front of it as long as the pressure at the back of the membrane remains the same.
A converter to adjust the amplitude to the desired strength of the signal. Transmits forward into the process.
A frequency sensor/discriminator An “electrical signal” producer A “wire” or connection to the brain. A Brain A program in the brain’s computer (cortex)
that converts the signal into something perceived as sound.
![Page 10: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/10.jpg)
The Ear
![Page 11: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/11.jpg)
![Page 12: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/12.jpg)
collection
sensorad
just
men
t
freq. separate
wire
BrainBalance
![Page 13: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/13.jpg)
In the beginning … Paramecia patrol the ooze of early life
A spot detects levels of light (not yet an eye) She chemically senses her environment (not yet a
nose) She can sense collisions with objects (but not a sense
of touch) During first 80 % of the 3.5 billion years that
evolution proceeded Flatworms, mites and rotifers (whatever they may be) eyes, sense of touch, chemical receptors (taste?) No sound at all.
200,000,000 years later, the ear began to emerge.
![Page 14: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/14.jpg)
![Page 15: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/15.jpg)
canal to inner ear Deflects sound in
1 in 4 have a bump here
Pinna amplifies (resonance) the higher frequencies – consonants
Catches, reflects snd.
![Page 16: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/16.jpg)
Ear canal resonance
MinimalAmplification
1.0
100Later!
![Page 17: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/17.jpg)
Pinna
Ear C
anal
Ear Drum
Eustachian Tume
![Page 18: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/18.jpg)
Atm. Pressure
![Page 19: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/19.jpg)
Cochlea
![Page 20: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/20.jpg)
We have collected the sound and applies a bit or resonance via the pinna folds.
We sent the sound down the ear canal. We have moved the eardrum with the sound. We connected the eardrum to the cochlea.
It is NOT a dirty word!
![Page 21: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/21.jpg)
Balance
Frequency&
Transmissionto the brain.
AS COILED IN THE EAR
![Page 22: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/22.jpg)
![Page 23: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/23.jpg)
High
response
Low
![Page 24: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/24.jpg)
high frequency low frequency
crosssection
high frequency (Stiff) low frequency
What would a wave traveling down the basilar membranedo to the shape of the membrane??
f
![Page 25: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/25.jpg)
RESO
NAN
CE
![Page 26: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/26.jpg)
Incompressible
compressible
![Page 27: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/27.jpg)
Inne
rOut
er
![Page 28: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/28.jpg)
Brain
Many fire at the same time
![Page 29: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/29.jpg)
Neurons can spontaneously fire at a rate of a few tens of Hz.
It is the CHANGE in rate that IS the neural message.
The collector nerves are often in contact with more than one hair cell.
If a cell fires, there is a time before it can fire again.
![Page 30: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/30.jpg)
![Page 31: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/31.jpg)
![Page 32: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/32.jpg)
Long exposure to loud (later) music can literally fracture the hair cells.Those cells no longer respond to sound.This can lead to deafness.There is a “Society for Deaf Musicians” that
is a result of this. Modern bands usually take precautions.
Very loud noise can shatter an eardrumMay recover, may not.
Nerves can die. Bad news.
![Page 33: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/33.jpg)
Age 40Ear is only 10% of what it was when you
were younger. Age 80
You have lost most of your high frequency hearing so the “quality” of what you hear changes significantly.
Consonants sound in the high frequency region which explains why older people have difficulties hearing (without any pathology).
![Page 34: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/34.jpg)
You lose ½ Hz. per day in high frequency hearing.20,000 Hz. 10,000 Hz. 7000 Hz.
Dead Most music is in the <4000 Hz. range so
it is ok to put a stereo in your casket. As you age, you lose sensitivity to the
higher harmonics of some instruments.
![Page 35: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/35.jpg)
Move to
find dire
ction
![Page 36: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/36.jpg)
Slight delay due to different distances.
Pinna “bouncing” leads to different quality that the brain can sense
Can’t do this for long wavelengths
![Page 37: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/37.jpg)
Distance Effect Phase Amplitude
Pinna Effect Large
Amplitude and Phase differences are minimal Localization is difficult.
Very Low frequencies, hearing doesn’t work too well (next slide) soDANGER!!!
![Page 38: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/38.jpg)
Loudness Recruitment Cells lose sensitivity to low or moderate sound
intensities but respond normally at high intensities.
Beethoven had this problem!
loudness (soon)
HearingNormal Response
![Page 39: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/39.jpg)
Log of a number (for our purposes) is the number of zeros that it containswhen written as an integer.
Number of dB
X Zeros Log(X) 10 x Log(X)
10 1 1 10
100 2 2 20
1000 3 3 30
10000 4 4 40
100000 5 5 50
1000000 6 6 60
0
log10I
Idb
Let I0 be the lowest intensity (defined next time … use your imagination for now) of sound that you can hear. db or decibel definition:
![Page 40: Can you ear me?? Hearing & the ear](https://reader036.fdocuments.net/reader036/viewer/2022062321/56813c94550346895da64317/html5/thumbnails/40.jpg)