Chapter 11-Introduction to the auditory system

Question 1

What is the physical aspect of sound?

Answer 1

Pressure changes in the air- or other physical mediums

Question 2

What is the perceptual aspect of sound?

Answer 2

The experience of hearing

Question 3

If a tree falls in the woods and no one is around to hear it; is there a sound according to the physical aspect

Answer 3

Yes there’s a sound bc here was a change in air pressure

Question 4

If a tree falls in the woods and no one is around to hear it; is there a sound according to the perceptual aspect?

Answer 4

No there was not a sound because nobody was around to experience the tree falling

Question 5

What is condensation?

Answer 5

AKA compressed
When a force pushes surrounding air molecules together causing a slight increase in air molecule density around the origin of the force leading to an increase of air pressure above atmospheric pressure

Question 6

Do air molecules move during condensation and refraction?

Answer 6

Not a lot- similar to if a small boat floating in a puddle is interrupted by a pebble falling, the boat will bob up and down

Question 7

What is rarefaction?

Answer 7

when there is a decrease in density of air molecules following condensation, resulting in lower air pressure

Question 8

What does a cycle of rarefaction and condensation cause?

Answer 8

a soundwave

Question 9

What kind of soundwaves are pure tones?

Answer 9

Sine waves

Question 10

What is a frequency?

Answer 10

The amount of cycles per second that pressure changes repeat

Question 11

What pitch does a higher frequency usually have?

Answer 11

Usually a higher pitch

Question 12

What is the frequency of a pure tone/sine wave?

Answer 12

1/t (Hz)

Question 13

What is amplitude?

Answer 13

The difference of the pressure change between the high and low peaks of a sound wave

Question 14

What is the result of a larger amplitude

Answer 14

A louder sound

Question 15

What represents a pitch change

Answer 15

darkening–> increased pressure
Lightening–> decrease in pressure

Question 16

How is amplitude measured?

Answer 16

decibels–> this is a physical measurement

Question 17

What range of Db can humans tolerate

Answer 17

0dB (barely audible) 160dB- pain threshold (jet plane taking off)

Question 18

What is the connection between dB, loudness and amplitude

Answer 18

Amplitude is the change between the highest and lowest points of a wave. The larger the change in amplitude, the louder the sound. Loudness is dependent on the frequency of the wave and the dB This sound is measured in dB.

Question 19

Can pure tones vary in frequency?

Answer 19

yes

Question 20

How are frequency and pitch connected?

Answer 20

The frequency of a sound is linked to the perception of pitch. So a high frequency is equal to a high pitch.

Question 21

What is a key difference between frequency and pitch?

Answer 21

Frequency is physical and can be measured. Whereas pitch is perceptual and cannot be measured- therefore it is very subjective

Question 22

Define tone height

Answer 22

a perceptual experience of increasing pitch as sound frequency increases.

How we perceive pitch

this is the basis of the music industry

Question 23

What is an example of tone height?

Answer 23

Keyboards have repeating notes A-G. These notes that are repeated but sound different are an octave apart and have the same tone chroma

Question 24

Define an octave?

Answer 24

Describes music notes and other sounds

Question 25

What is the audibility curve?

Answer 25

A threshold for Hearing (dB) vs Frequency (Hz)

Question 26

What is Timbre

Answer 26

The quality that allows us to find a difference between two tones with the same loudness, pitch and duration

Question 27

What is an additive synthesis?

Answer 27

multiple frequencies that make up complex tones depends on the harmonic structure and the attacks and decays of the tones harmonics

Question 28

What is the effect of the missing harmonic?

Answer 28

The timbre changes when a harmonic is missing. However it does not changed the perceived pitch

Question 29

What is the attack of tones?

Answer 29

The build-up of sound of a tone Not necessarily at the beginning of the note- depends on the instrument ex. when a piano plays the notes are high attack at the beginning because intensity comes at the beginning from the hammer hitting the string. Whereas an organ has a high attack at the end of a note because the intensity builds.

Question 30

What is the decay of tones?

Answer 30

The decrease in sound at the end of a tone

Question 31

Define Periodic

Answer 31

a pattern of pressure changes that repeat ex. musical notes/pure tones

Question 32

Define aperiodic

Answer 32

a pattern of sound waves that does not repeat ex. a door slamming

Question 33

What does the outer ear consist of?

Answer 33

Pinna auditory canal Eardrum/tympanic membrane

Question 34

What does the middle ear consist of?

Answer 34

Ossicles- malleus, incus, stapes middle ear muscles oval window

Question 35

What does the inner ear consist of?

Answer 35

Semicircular canals Round window cochlea

Question 36

What is the pinnae?

Answer 36

the part of the ear on the outside of the head

Question 37

What is the function of the auditory canal?

Answer 37

to amplify sound within 2000-5000 Hz via resonance

Question 38

Define resonance

Answer 38

when sound waves are reflected off the tympanic membrane to create constructive interference with oncoming waves.

Question 39

What is the tympanic membrane/eardrum?

Answer 39

found at the end of the auditory canal and borders the middle and outer ear

Question 40

What is the general function of the middle ear?

Answer 40

To amplify sound

Question 41

What are the ossicles?

Answer 41

Three of the smallest bones in the body consist of the melleas, incus and stapes

Question 42

What are the functions of the ossicles bones?

Answer 42

They are responsible for amplifying sound Connect the tympanic membrane to the cochlea

Question 43

What is the order in which the ossicle bones are found from closest to the outer ear to closest to the inner

Answer 43

Malleas, incus, stapes

Question 44

What are the common names for the mallaes, incus and stapes in that respective order?

Answer 44

hammer, anvil, stirrup

Question 45

What is the purpose of muscles in the middle ear?

Answer 45

they dampen the vibrations of the ossicles

Question 46

How does amplification in the middle ear work?

Answer 46

The vibrations are concentrated by the ossicles to a smaller are this increases the pressure from the vibrations by aprox 17 times

Question 47

Why is amplification so important in the middle ear?

Answer 47

Because the inner ear is full of fluid, therefore if vibrations are not strong , there is no way that sound can pass through to the inner ear

Question 48

Why do fish lack outer and middle ear structures?

Answer 48

Because they live in water- water and the fluid found in the cochlea/inner ear have similar densities

Question 49

What is found in the inner ear?

Answer 49

the cochlea organ of corti Hair cells basilar membrane apex

Question 50

How is the cochlea built?

Answer 50

split into two structures by the cochlear partition. These two structures are known as the scala vestibuli and the scala tympani

Question 51

Where is the organ of corti found?

Answer 51

On the outer spiral of the cochlea

Question 52

What is the function of the organ of corti?

Answer 52

Where transduction for sounds takes place--> sounds turn into neural activity

Question 53

What are the two parts the cochlea is broken into?

Answer 53

Scala vestibuli Scala tympani

Question 54

How are the scala vestibuli and scala tympani different

Answer 54

The scala vestibuli is the top half of the cochlea and extends from the oval window to the apex. Whereas the scala tympani is the bottom half of the cochlea and extends from the round window to the apex

Question 55

what is found in the organ of corti?

Answer 55

one row of cilia three rows of outer hair cells

Question 56

What is found in the scala media?

Answer 56

Fluid

Question 57

What is the difference between inner and outer hair cells in the organ of corti?

Answer 57

inner hair cells diverge, with each cell connecting to 8-30 auditory nerve fibres. Whereas outer hair cells converge, so each auditory nerve is connected to multiple outer hair cells

Question 58

How is the transduction process initiated?

Answer 58

Cilia, connected to hair cells bend which is how transduction starts

Question 59

How does information get through the cochlea?

Answer 59

1. The stapes vibrates, making the oval window vibrate. 2. This causes pressure changes in the cochlear fluid.