4.4 Audition: More Than Meets the Ear

Question 1

How does the sense of hearing work?

Answer 1

Sound waves; detecting changes in air pressure unfolding over time

Question 2

What are the three physical dimensions of a sound wave?

Answer 2

Amplitude

Frequency

Complexity

Question 3

How does Frequency change sound?

Answer 3

Frequency affects the PITCH heard.

Difference in frequency is characterized as a change in Wavelength

Question 4

How does Amplitude change sound?

Answer 4

Amplitude affects the LOUDNESS of the sound.

Difference in wave height is defined as a change in Amplitude

Question 5

How does Complexity change sound?

Answer 5

Complexity changes the TIMBRE of the sound. This can be described as the quality or clarity of the sound heard.

Complexity is the mix of sound frequencies

Question 6

How does our anatomy contribute to localizing sound sources?

Answer 6

We have two ears on opposite sides of our heads. Our heads block the sound from entering each ear equally.

Our ears also receive sounds at slightly different times, since they’re in different locations.

Question 7

What are the three distinct parts of the human ear?

Answer 7

Outer ear

Middle ear

Inner ear

Question 8

What is the primary/basic function of each of the three parts of the ear?

Answer 8

Outer - Collect and funnel sounds into the Middle ear

Middle - Transmits vibrations to the Inner Ear

Inner - Transduces vibrations into neural impulses

Question 9

What’s the outermost part of the ear called?

Answer 9

Pinna

Question 10

What parts of the ear are included in the Outer ear?

Answer 10

Pinna—> Auditory Canal

Question 11

What parts of the ear are included in the Middle ear?

Answer 11

Eardrum—> Ossicles—->

Question 12

What parts of the ear are included in the Inner ear?

Answer 12

Cochlea—-> Semicircular canals

Question 13

Describe the composition of the Cochlea;

Answer 13

A fluid-filled tube that is the organ of auditory transduction

Houses the BASILAR MEMBRANE + HAIR CELLS

Question 14

What does the Cochlear Membrane do?

Answer 14

A structure in the inner ear that undulates when vibrations from the ossicles reach the cochlear fluid

Question 15

What are Hair Cells?

Answer 15

Specialized auditory receptor neurons embedded in the basilar membrane

Theyrelease neurotransmitter molecules, initiating a neural signal in the auditory nerve that travels to the brain

Question 16

Where do action potentials in the auditory nerve travel to?

Answer 16

The Thalamus and ultimately to an area of the Cerebral Cortex called the primary auditory cortex (also called area A1) in the Temporal Lobe

Question 17

What do the auditory regions of the left and right hemispheres do?

Answer 17

the auditory region of the LEFT hemisphere analyzes sounds related to LANGUAGE

the RIGHT hemisphere specializes in RHYTHMIC sounds and music

Question 18

What are the two distinct streams of the auditory regions?

Answer 18

Spatial (where); allow you to locate the source of a sound in space, are handled by areas towards the back

Non-Spatial (what); allow you to identify the sound, are handled by areas in the lower (ventral) part of the auditory region

Question 19

What is Place Code?

Answer 19

The process by which different frequencies stimulate neural signals at specific places along the basilar membrane, from which the brain determines pitch

Question 20

What range of frequencies is the human ear most sensitive to?

Answer 20

1000 to 3500Hz

Question 21

What part of the basilar membrane moves the most from low-frequency sounds?

Answer 21

Apex (floppy tip)

When the frequency is low, the wide, floppy tip (apex) of the basilar membrane moves the most

Question 22

What part of the basilar membrane moves the most from high-frequency sounds?

Answer 22

Base (stiff end)

Question 23

Define “Temporal Code”

Answer 23

The process whereby the cochlea registers low frequencies via the firing rate of action potentials entering the auditory nerve (up to ~5000Hz)

Question 24

Conductive Hearing Loss

Answer 24

Arises because the eardrum or ossicles are damaged to the point that they cannot conduct sound waves effectively to the cochlea (Middle ear)

In many cases, medication or surgery can correct the problem.

Question 25

Sensorineural Hearing Loss

Answer 25

Caused by damage to the cochlea, the hair cells, or the auditory nerve, and it happens to almost all of us as we age. (Inner ear)

Sensorineural hearing loss can be heightened in people regularly exposed to high noise levels.

Hearing sensitivity can also be lost in this type, creating “blurry hearing”

Question 26

Cochlear Implant

Answer 26

An electronic device that replaces the function of the hair cells

The implanted parts include a receiver just inside the skull and a thin wire containing electrodes inserted into the cochlea to stimulate the auditory nerve. Sound picked up by the microphone is transformed into electric signals by the speech processor, which is essentially a small computer. The signal is transmitted to the implanted receiver, which activates the electrodes in the cochlea.

Question 27

In which type of hearing loss does sound amplification help?

Answer 27

Sensorineural

Question 28

Musicians have greater plasticity in the ________, compared with non-musicians

Answer 28

Motor Cortex