Sound/HearingSensation & Perception

Characteristics of Sound

• Frequency– corresponds to the perceptual term pitch.

•Wavelength – Hertz (Hz) – waves (cycles) per second–Pitch

• High• Low

Properties of Sound

Perceiving Pitch

• Place Theory– The pitch we hear is linked to a particular

place where the cochlea’s membrane is stimulated

• Frequency Theory– The rate of nerve impulses traveling up the

auditory nerve matches the tone

Perceiving Pitch

• Problem: individual neurons can’t fire faster than 1000 times per second, but we can hear frequencies abobe that.

• Solution: The volley principle.– Neural cells alternate firing to achieve faster

responses.

Characteristics of Sound

• Amplitude – corresponds to the perceptual term

loudness (volume).

Characteristics of Sound

• Frequency– corresponds to the perceptual term pitch.

• Amplitude – corresponds to the perceptual term

loudness (volume).• Complexity

– corresponds to the perceptual term timbre (quality).

Properties of SoundComplexity: A violin and a piano sound different, even

though they may be playing the same note.

The Ear

The ear is divided into the outer, middle and inner ear.

The Ear

The sound waves travel down the auditory canal to the eardrum.

The Ear

Eardrum = tight membrane that vibrates when struck by sound waves.

The Ear

Bones of the middle ear = the hammer, anvil, stirrup which vibrate with the eardrum.

The Ear

Cochlea = a coiled, body, fluid-filled tube in the inner ear through which sound waves

trigger nerve impulses.

The Ear

Auditory nerve = nerve which sends the auditory message to the brain via the

thalamus.

Hearing Loss

• Conduction Hearing Loss– Caused by damage to the mechanical

system that conducts sound waves to the cochlea

• Sensorineural Hearing Loss– Caused by damage to the cochlea’s receptor

cells or to the auditory nerve• Teen hearing loss has risen by one-third

since the early 1990s. 1 in 5.

Hearing Loss

• Hearing Aids– Increase amplitude on

specific frequencies– Cochlear Implants

convert sounds into electrical signals and stimulate the auditory nerve.

Cochlear implant example #1

Anna’s Activation

Type Cochlear implant into youtube’s search box for more.

Locating Sounds

• Sound waves strike one ear sooner and more intensely than the other.

Assignment

• AP Psychology: Read Module 21 “The Other Senses” pages 202 – 212 before Wednesday.

• Psychology 1: Read modules 7.6 about taste and smell (pages 88-90) and 7.7 about other sensory systems (pages 91-92) before Wednesday.