Chapter 6: Hearing

Physiological psychology

What is the first part of a sound wave that we are aware of?

The frequency or how often the sound wave occurs

How are sound waves measured?

They are measured from one peak to the next peak. This is measured by hertz (Hz)

How many sound waves can human hear?

From 20-20,000 Hz

Apart from the frequency of sound waves, what is another characteristic that we are aware of?

The amplitude of the sound wave

How is amplitude measured?

It is measured from peak to trough and measured in decibels (Db)

What does amplitude relate to?

The intensity of the sound

True or False: We process incoming sound waves based on their complexity

True

How do we process incoming sound waves?

Based on their complexity

What do we refer to as incoming sound waves based on their complexity?

Timbre 

What does the complexity of a sound wave refer to?

The overtones that you hear

What do the overtones that we hear help distinguish?

The difference between someone playing a C note on a piano and a C note on a violin

What is a the pinna?

It is the part of the ear that we can actually see 

What is the purpose of the pinna?

To capture the sound wave from the environment and funnel it towards the inner ear

The larger the pinna__

The more information that can be received from a greater distance

Where does the pinna channel sound waves that come from the enviornment?

Into the middle ear

What would happen if someone’s pinna were sticking straight out?

That individual is limited in their perception of sound waves. They miss the information that is coming to them from their side

What can misshapen pinna create?

They can create up to 60% hearing loss

Once the sound wave is captured by the pinna, where is it channeled into?

The auditory canal

Where is the boundary between the outer ear and the middle ear?

At the end of the auditory canal

Where does the auditory canal end?

At the tympanic membrane

What is the tympanic membrane?

A thin layer between the outer ear and the middle ear also known as your eardrum

What is the tympanic membrane surrounded by?

Air on both sides

The middle ear is filled with air but where does that air come from?

From your oral cavity

Where does the tympanic membrane transmit the sound wave to?

Three smallest bones called ossicles

Where are ossicles located in our ear?

In the middle ear

What are the tree ossicles called?

Malleus, incus, and stapes

What are the functions of ossicles?

To transmit and amplify the sound wave from the outside world to the inner ear

What is the boundary into the inner ear known as?

As the oval window

Why is the amplification of the sound wave important?

Because the structure behind the oval window, the cochlea, is filled with fluid

What is the cochlea?

A snail-shaped structure that is divided into 3 fluid-filled canals

What are the 3 fluid-filled canals that make up the cochlea?

The vestibular duct, cochlear duct, and tympanic duct

What is the inner tunnel of the cochlea called?

The Scala media. It is bordered by the Scala vestibuli on top and the Scala tympani on the bottom

What does the scala media contain?

The organ of corti which houses the receptors for hearing

What are the actual receptors for hearing called

Hair cells and they are mounted on the basilar membrane

What are a part of the organ of corti?

Hair cells and the tectorial membrane

As sound waves travel through the scala media, what does the basilar membrane do?

It moves, and its movement causes the hair cells to bend against the tectorial membrane.

What does the bending of the hair cells do?

It stimulates these hair cells to produce an action potential, which is sent along the auditory nerve to the brain

How many sets of hair cells are in how many rows?

Two sets of hair cells in four rows

In order to amplify the incoming sound wave, humans rely on…?

The ossicles in the middle ear and the hair cells in the cochlea

Where does the auditory nerve begin?

In the cochlea

What happens once the aurditory nerve begins?

It send information to the brainstem and then to the inferior collicus in the midbrain. 

What happens after receiving auditory signals?

The inferior colliculus forwards this info to the medial nucleus in the thalamus and then to the primary auditory cortex.

What is one of the theories about how we determine what sound we hear?

The predominant theories

What is the predominant theory?

Cochlear place coding theory. Different frequencies produce maximal stimulation of hair cells at different points along the basilar membrane

What is a predominant theory believed to be?

A tonotopic organization of the basilar membrane

What is the tonotopic organization of the basilar membrane?

It is where higher-pitches sounds are senses newr the oval window while lower pitches soundes are sense at the apex. 

Why are high-pitched sounds near the oval window?

The area is narrower and stiffer, so it is more sensitive to higher frequencies

Why are low-pitches sounds near the apex?

The apical end is wider and less stiff, which is more responsive to lower frequencies

Besides the predominant theory, what is a second theory of hearing?

The temporal coding theory

What is the temporal coding theory?

The perception of tone depends on the frequency at which hair cells fire

How do we localize the origin of a sound?

We use the difference in sound between our two ears: Binaural cues

What are binaural cues?

They are cues that allow us to localize sound

How do binaural cues help us localize sound?

Latency differences between the ears. The ear that is closest to the sound will be aware of it first before the ear that is furthest. The same goes for how loud it is.

When would be the only times we do not know where a sound is coming from?

When it is directly behind us, above us, or below us.

How loud is a whisper?

20 Db loud

How loud is typical speech

60 Db

If you have mild hearing loss, how loud is a whisper?

40 Db

What reflex protects your ears so they are not damaged due to exposure to a sudden loud noise?

Acoustic stapedius reflex

How does the acoustic stapedius reflex protect your hearing?

They are muscles that are tightened to prevent the bones from slamming into the oval window

What are problems that can cause hearing loss?

Meningitis, chicken pox, and listening to very loud music

Regular exposure to loud noises can cause…?

Hearing loss and tinnitus

What is tinnitus?

It is a high-pitched noise after being exposed to loud music for a few hours

What happens in the ear when experiencing tinnitus?

It is due to the damage of the hair cells in the inner ear

Does tinnitus last forever?

No but if it does, it can suggest an underlying medical condition

How can tinnitus be cured?

There are no medications to treat nerve damage. You may have to undergo surgery or use hearing aids,

True or False: Another form of hearing loss is conductive deafness

False. That results in deafness

What is conductive deafness?

A type of deafness that can occur if there is a problem conducting the sound wave from the environment to the inner ear

What type of deafness involves damage to the brain regions that process sound?

Central deafness

What do people experiencing central deafness hear?

They can hear sounds, but they cannot make sense of what they hear

Physiologically, what is connected to the auditory system?

Vestibular system

What is the vestibular system?

It is a structure that is found within the inner ear, and it helps us maintain balance and posture

What are the semicircular canals of the vestibular system?

They are a jellylike substance that is lined with hair cells. They are sensory receptors that send information to the brain regarding our balance and posture

What are otolithic organs?

They send information the to brain about the position of our head.

How many otoliths are there?

2, utricle and saccule

What is vertigo?

It is when a person feels like they are moving or there is movement around them when there is not 

What can vertigo result from?

From a problem in the semicircular canals of the ear