Sound Properties

Question 1

Air

Answer 1

Made up of molecules and spaces between these molecules

Question 2

Elasticity

Answer 2

A property of air that causes air molecules that have been compressed together to spring apart.
Expl. Blowing up a balloon compresses the air molecules inside the balloon. When the balloon is popped, the air molecules spring apart.

Question 3

Compression

Answer 3

Occurs when air molecules are pushed together by a sound source.
Expl. Pulling back a guitar string and letting it go.

Question 4

Rarefaction

Answer 4

The area where there are fewer molecules than before because of the compressions.

Question 5

Compression Waves

Answer 5

A series of compression and rarefaction that propagate(move) through the air.

Question 6

Sound

Answer 6

Compression waves created by a vibrating body including:
- Strings
- Mouthpiece(brass / wood instruments)
Vocal Chords

Question 7

Sampling*

Answer 7

Recording real sounds and making them available on the keyboard

Question 8

Resonance

Answer 8

When the initial sound wave is passed through the body of an instrument in order to modify its pitch and timbre.

Example: The body of a violin or guitar is a resonator for the sound waves created by the strings.

Question 9

The Human Ear

Answer 9

Allows us to hear compression waves and can be divided into 3 basic parts:

• Outer Ear
• Middle Ear
• Inner Ear

Question 10

The Outer Ear

Answer 10

Consists of the Pinna and the Ear Canal.

Question 11

Pinna

Answer 11

The flesh on the outside of your head. It helps us locate the sound source and slightly filters the sound.

Question 12

Ear Canal

Answer 12

The length and shape of the ear canal emphasizes frequencies between 2,000 - 5,000 Hz

Question 13

The Middle Ear

Answer 13

Consists of the tympanic membrane (eardrum).

Question 14

Eardrum

Answer 14

Vibrates sympathetically with the incoming sound waves.

Example: A loud instrument played toward the head of a drum will cause the rum to vibrate without being struck.

Question 15

The Inner Ear

Answer 15

Consists of the Cochlea

Question 16

Cochlea

Answer 16

A fluid filled tube that is coiled up like a snail. The fluid in the cochlea vibrates an converts the vibration into neural impulses that are sent through the auditory nerve to the brain.

Question 17

Hearing Loss

Answer 17

Age and exposure to loud sounds cause the cochlea to become gradually less receptive to high frequencies.

Question 18

Physical Properties

Answer 18

The measurable properties of sound.

Example: Frequency is a physical property and is measured in Hz.

Question 19

Perceptual Properties

Answer 19

Are created by the brain in response to the physical properties of sound.

Example: Pitch is the perceptual property associated with frequency.

Question 20

Frequency (Physical Property)

Answer 20

Is the rate at which a sound moves through a full cycle.

Question 21

Waveform view

Answer 21

A graph of the change in air pressure at a particular location in time. It shows compression and rarefaction.

Question 22

Hertz(Hz)

Answer 22

the unit used to measure frequency

Question 23

Human Audio Range

Answer 23

The range of frequencies that humans are able to perceive as sounds. The human audio range is 20 Hz to 20,000 Hz (20 kHz). Human audio ranges vary from person to person and decrease over time, losing high frequencies.

Question 24

Ultrasonic Frequencis

Answer 24

Are above the human audio range.

Question 25

Infrasonic Frequencies

Answer 25

Are below the human audio range.

Example: Elephants can communicate below 20 Hz.

Question 26

Pitch (Perceived Property)

Answer 26

Is a measurement of sound made by our brains when we perceive frequency. Pitch is measured in a musical note values.
Example: The frequency 440Hz is perceived by our brains to the pitch of “A”

Question 27

Amplitude (Physical Property)

Answer 27

Is determined by how much the pressure in a compression wave differs from the normal air pressure.

• Plucking a string harder increases its amplitude.
• Amplitude is expressed as the height of the wave in the waveform view.

Question 28

Decibels of Sound Pressure (dB spL)

Answer 28

The unit used to measure amplitude.

Question 29

Timbre

Answer 29

Also known as tone color or tone quality, is the perceived sound quality of a musical note, sound or tone

Question 30

Threshold of hearing

Answer 30

is the quietest sound we can possibly hear and is represented by 0 db SPL

Question 31

Threshold of Pain

Answer 31

is the loudest sound we can bear without extreme pain and physical damage to our hearing. It is approximately 120 db SPL

Question 32

Temporary Threshold Shift

Answer 32

The sensation of having your hearing dulled or muted after exposure to sounds above 90 db SPL.
- Usually lasts a matter of hours in a day but can become permanent threshold shift.

Question 33

Tinitus

Answer 33

is the technical name for the ringing in your ears after your hearing has been damaged.
- Can be temporary or become permanent.

Question 34

Loudness (perceived property)

Answer 34

is the measurement of sound made by our brains when we perceive amplitude (volume)