Working with Sounds

Question 1

What is a sound?

Answer 1

A propagated disturbance in the ambient pressure of a medium (air, water, etc.)

Question 2

What is a signal?

Answer 2

A perceivable behaviour/feature that has evolved and has acquired the specific characteristic of conveying information about the signaller or the signaller’s environment

Question 3

What is a cue?

Answer 3

Any feature or pattern produced by an organism without the purpose of communication, from which other organisms can obtain information

Question 4

How does a microphone work?

Answer 4

It converts the variations in pressure created by a passing sound wave into electrical signals that mimic the rise and fall of sound pressure at the microphone

Question 5

How do you measure frequency?

Answer 5

f= 1/T (in seconds)

Question 6

Name two ways in which amplitude can be measured

Answer 6

1) peak to peak

2) RMS (root mean square)

Question 7

Define amplitude

Answer 7

A measure of the average variation in pressure associated with the sound

Question 8

Define the Fourier analysis

Answer 8

The analysis of a complex waveform expressed as a series of sinusoidal functions, the frequencies of which form a harmonic series

Question 9

Fourier analysis

Any periodic function can be written as the _____________ with __________ and _________ values that can be measured

Answer 9

Any periodic function can be written as the SUM OF PURE SINE WAVES with FREQUENCY and AMPLITUDE values that can be measured.

Question 10

What body part is the generator of sound?

Answer 10

The larynx (also known as the voice box)

Question 11

What body parts does the larynx connect?

Answer 11

It connects the pharynx (throat) with the with the trachea (windpipe)

Question 12

What is the epiglottis and how does it work?

Answer 12

It is a small flap at the top of the larynx that prevents food and water from entering the voice box. When you swallow, the larynx rises to meet the epiglottis to seal off the trachea.

Question 13

What and where are the vocal cords?

Answer 13

They are two strips of tissue found in the larynx.

Question 14

Is a higher or lower pitch created when the vocal cords are pulled tighter?

Answer 14

A higher pitch is created

Question 15

What is the source-filter theory?

Answer 15

Speech can be seen as a source signal produced in the larynx and then filtered by the cavities of the vocal tract

Question 16

What do ‘tubes’ in the vocal tract do?

Answer 16

They act as an acoustic resonator or filter

Question 17

What do ‘valves’ in the vocal tract do?

Answer 17

1) Open and close the vocal tract to some tubes

2) Serve as sound source

Question 18

Summarise what was discovered concerning fallow deer vocalisations

Answer 18

1) Body size affects Formant Frequencies

2) Dominant status affects fundamental frequency or pitch

Question 19

What are formants?

Answer 19

They are broad peaks in the spectrum of a complex sound. They correspond to frequencies of vocalisations that are amplified by the vocal tract.

Question 20

Define frequency

Answer 20

The number of crests of the sound wave that pass a given point in one unit of time

Question 21

What is the fundamental frequency?

Answer 21

It is the lowest harmonic of a multi-harmonic sound. It is produced by the vibration of a sound-producing object over its full length, while higher harmonics correspond to modes of vibration in a fraction of the length

Question 22

What is a harmonic?

Answer 22

It is a sound wave whose frequency is an integer multiple of a reference frequency, so if the reference frequency is f then the harmonics will have frequencies 2f, 3f, 4f etc. The reference frequency is called the fundamental frequency

Question 23

Define pitch

Answer 23

the quality of a sound governed by the rate of vibrations producing it; the degree of highness or lowness of a tone.

For pure tones (tones that can be described as a single sine wave), the pitch tends to follow the actual frequency of the sound quite closely.