Class 8: Audition

In the cochlear nucleus, bands of cells with similar characteristic frequencies (increase/decrease) from anterior to posterior.

Increase

(Inner/outer) hair cells are responsible for sound transduction.

Inner

The ________ membrane overlies the hair cells embedded in the basilar membrane. Every time the hair cells move, they hit this membrane.

Tectorial

Tonotopy is preserved in which two places?

-Auditory nerve -Cochlear nucleus

To encode information about stimulus intensity, you should examine what two things?

-Firing rates of neurons -Number of active neurons

High pitch corresponds to (high/low) frequency. Low pitch corresponds to (high/low) frequency.

-High -Low

What are the three ossicles and where in the ear are they located?

-Malleus, incus and stapes -The middle ear

What are the three auditory pathways?

-Outer ear -Middle ear -Inner ear

Vibration of the ________ window results in fluid displacement and eventually in displacement of the ________ window.

-Oval -Round

High frequency has a (small/long) wavelength and low frequency has a (small/long) wavelength.

-Small -Long

The pinna enhances ______ to ______ kHz of sound in humans.

1.5 to 7 kHz

What is the audible sound range for humans?

20 Hz to 20,000 Hz

Loudness perceived is correlated with the number of _________ __________.

Active nerons

The middle ear helps with sound _________. Small vibrations in the tympanic membrane cause auditory responses.

Amplification

The __________ of a wave is its maximum disturbance from its undisturbed position.

Amplitude

Low frequency sounds are detected by the (base/apex) of the basilar membrane.

Apex

The cochlea is wider at the (base/apex).

Apex

The ________ ________ is a response when the onset of a loud sound causes tympanic muscle contraction.

Attenuation reflex

High frequency sounds are detected by the (base/apex) of the basilar membrane.

Base

The cochlea is stiffer at the (base/apex).

Base

Embedded in the _________ membrane are hair cells that are connected to stereocilia.

Basilar

The ________ frequency is the frequency at which a neuron is most responsive - from cochlea to cortex.

Characteristic

_______ ________ is when a neuron or a neural circuit can encode information by detecting the occurrence of temporally close but spatially distributed input signals.

Coincidence detection

Sound is a change in local _________ of molecules that is perceived by a receiver.

Concentration

A _______ is the distance between successive comprehensive patches of air.

Cycle

A ________ is the angle that describes the relative starting position of a wave, or how more than one wave relates to one another.

Cycle

_______ ________ refers to the lag in time between one ear hearing something and the other, and the intensity difference between ears due to your head's sound shadow.

Delay lines

________ fluid movement bends the basilar membrane near the base, and the waves move upwards.

Endolymph

________ is fluid in the scala media.

Endolymph

(True/false) Receptors are very sensitive to wave phases.

False, they are not. But some neurons are!

(True/false) A sound coming towards somebody head on still requires the delay lines principle.

False. There's no sound shadow head on.

What is the main function of the pinna?

Filtering sound. It also protects the middle and inner ear.

Sound _________ is the number of cycles per second expressed in hertz (Hz).

Frequency

Hair cells in the auditory system have vesicles filled with what NT?

Glutamate

Sound going from air to water experiences acoustic impedance. Where does this happen in the ear?

Going from the auditory canal to the fluid filled middle ear.

(High or low frequencies?) Phase locking is not fixed.

High frequency

(Lower/higher) frequencies do better in open areas with no hard surfaces.

Higher

Without a pinna, humans can locate sound on a (horizontal/vertical) plane.

Horizontal

Acoustic __________ measures of the opposition that a system presents to the acoustic flow resulting of an acoustic pressure applied to the system.

Impedance

(Sound localization on a horizontal plane) Interaural _________ difference is when sound at one ear is less intense because of the head's sound shadow.

Intensity

(Sound localization on a horizontal plane) _______ time delay is the difference in time for sound to reach each other.

Interaural

What is the function of the attenuation reflex?

It adapts the ear to loud sounds, protects the inner ear, and enables us to understand speech better.

High intensity (amplitude) waves are (louder/softer) than low intensity.

Louder

(High or low frequencies?) Phase locking on every cycle or some fraction of cycles.

Low frequencies

(Lower/higher) frequencies do not get distorted around hard objects. They can bend around.

Lower

From the base to the apex, the basilar membrane resonates with increasingly (higher/lower) frequencies.

Lower

Hair cells in the auditory system are what kind of receptors?

Mechanoreceptors

(Delay lines) Impulses from left and right ears reach the ________ neuron at the same time. This leads to summation and then an action potential.

Olivary

Motion at the _______ window pushes perilymph.

Oval

________ is fluid in the scala vestibuli and scala tympani.

Perilymph

When auditory neurons fire action potentials, they tend to respond at times corresponding to a peak in the sound pressure waveform. This is called ________ ________.

Phase locking

The outer ear is called the ________. It can be mobile or stationary.

Pinna

A _______ _______ refers to the area on the basilar membrane that a certain frequency stimulates.

Place code

(Endocochlear potential) Endolymph electrical potential is 80 mV more (positive/negative) than perilymph.

Positive

What are the positively charged ions that cause depolarization in the auditory system?

Potassium

Movement of an oscillator causes ___________ changes which spread from the source.

Pressure

The force of medium molecules per unit area is _________.

Pressure

Vertical sound localization is based on ________ from the pinna.

Reflections

A ________ wave is a smooth periodic oscillation.

Sinusoidal

________ is audible variations in air pressure.

Sound

A ________ _________ is an area through which sound waves fail to propagate.

Sound shadow

The oval window articulates with the _______, while the round window is as the other end of the cochlea.

Stapes

(Delay lines) When sound comes from the left side, activity in the left cochlear nucleus is sent to the _______ _______. The sound delayed to the right ear stimulates activity in the right cochlear nucleus.

Superior olive

Which graph has a higher frequency?

The bottom graph.

If a sound comes from your right, your right ear will process it first, then your left ear second after it has gone around your head. How does coincidence detection prevent this by stimulating both ears at the same time?

The sound on the side of your head it came from travels in a longer path to give the sound time to travel to the ear on the other side of your head.

A sound coming from the left side of this diagram would stimulate which place code? Why?

The third. It travels a longer path so the sound can reach the other ear as the same time.

The middle ear is bounded by two membranes. What are they?

The tympanic membrane (eardrum) and the oval window.

Owls can locate sound on a horizontal and vertical plane. How?

Their entire face acts as a satellite dish that funnels sound into their ears.

What is the relationship between wavelength and frequency?

They are inversely related

What is the role of the ossicles?

They transmit a signal between the tympanic membrane and the oval window.

_________ is the spatial arrangement of where sound is perceived, transmitted, or received.

Tonotopy

The surface area of the stapes is much smaller than the tympanic membrane. This reduction in area accounts for efficiency in sound _________.

Transduction

(True/false) Time delay depends on the head size of the animal.

True

Does sound travel better through water or through air?

Water