HEARING EXAM

Period

Period

Time in seconds (don’t forget to convert msec to sec)

Periodic

Tonal, have pitch, vowels, integer multiple harmonic

Aperiodic

Noisy, no tone, no pitch, static, consonants, no clear organization

Pure sound aka sine wave

Not real in nature, only made by a machine, ONE sound

Find wavelengths

Wave length = c / f

What is the speed of sound ( c ) ?

343 m/sec

Find the frequency

F = 1/t

How to find the period of a complex periodic sound

Find the period of the lowest frequency t=1/f

Wavelength

Distance in meters (don’t forget to convert mm to m)

Convert 2 msec into seconds

.002

How do sound waves travel via air

Molecule vibration in an elastic medium

Compression

Positive pressure, top of wave

Rarefaction

Negative pressure, bottom of wave

When sounds fades, due to friction, its called

Damping

Sound wave propagation

Sound waves travel in all directions from the sound source

Frequency

Cycles per second, expressed in Hz

What is audiology?

Came from noise exposure from modern weaponry

What does presbycusis mean?

Age related hearing loss

What is hearing loss associated with?

Falls, depression, isolation, loneliness, reduced quality of life

Acoustic energy

Air molecule vibration

Mechanical energy

Ear drum, biological microphone

Electrochemical energy

Nervous system

Vibration

Tuning fork, a to-and-from motion

Properties of sound source vibration

Equilibrium (resting position)

Maximum displacement in one direction

Maximum displacement in another direction

Elasticity: wants to go back to equilibrium

Start at resting position, vibrates and restoring force because of inertia over shoots in the maximum direction and repeats until returning to resting

What is a vibration

A disturbance in both space and time (a wave)

Inertia

The tendency of an object set into motion to remain in motion

Elasticity

A physical property where a deformed object returns to its original form (related to restoring force)

Restoring force

The force that opposes the deformation of an elastic material or medium

Elasticity does not equal flexibility

Steel strings are more elastic than rubber strings because they resist more to the external force

Can you hear in a vacuum such as space?

Since there are no air molecules present to vibrate, there is no sound. There is no medium

The Doppler effect

Think of what you hear when a car comes towards you, away from you, or passes you left to right

Where do decibels come from

It’s a logarithmic scale to pascals

What is 0 decibels

Average quietest noise people can hear “reference value”