Bioaccoustics

Question 1

What is bioacoustics ?

Answer 1

The scientific study of biological sounds.

Question 2

What is bioacoustics concerned with ?

Answer 2

The production and propagation of sound in water and air
The reception of sound
Echolocation
The affect of manmade sound on organisms.

Question 3

Why is sound a useful signal ?

Answer 3

Works in darkness 
Works when organisms out of sight 
Omnidirectional (don't have to be facing one another) 
Enables localisation 
Sound can be adapted

Question 4

Describe how sound signals can be adapted.

Answer 4

Can be switched off
Can carry different meanings
Can cover a desired distance
Can be signal for partner selection

Question 5

Sound does not require a medium

True or False ?

Answer 5

False,

Sound must have air, water or other substrate

Question 6

How do sound waves oscillate ?

Answer 6

They oscillate (medium particles) relative to their resting position

Question 7

Give the key features of the Longitudinal sound wave.

Answer 7

Sounds in air and water
Propagation direction >
Oscillation direction

Question 8

Give the key features of the Transverse wave

Answer 8

Sounds in solids
Propagation direction >
Oscillation direction (up/down)

Question 9

What two separate speeds does sound involve ?

Answer 9

The propagation speed of the waves

The speed of the oscillating particle

Question 10

What is another name for the propagation speed of the wave ?

Answer 10

The speed of sound

Question 11

What is another name for the oscillation speed of the particle ?

Answer 11

The Particle velocity.

Question 12

What is the speed of sound in air ?

Answer 12

340 m/s (770mph)

Question 13

What is the speed of sound in water ?

Answer 13

1500 m/s

Question 14

What is the Particle velocity dependent on ?

Answer 14

Amplitude

Question 15

What is the Particle velocity at the threshold of pain ?

Answer 15

Only 0.16 m/s

Question 16

Who invented the Dezibel dB scale ?

Answer 16

Professor Graham Bell

Question 17

How is sound used in the mating selection of crocodiles ?

Answer 17

Males that emit roars at the lowest pitch have the largest bodies
Will be sexually selected by females

Question 18

How is sound pressure measured ?

Answer 18

As a change in the local pressure in Pascal’s

Question 19

What Is ambient pressure ?

Answer 19

101325 Pascal’s

Pressure exerted by the weight of the earth in most circumstances.

Question 20

What does sound pressure oscillate between ?

Answer 20

20 to 63 uPa

Question 21

The louder sound we perceive….

Answer 21

The higher the pressure oscillation amplitude, A

Question 22

How did Bell create the dezibel dB scale ?

Answer 22

Created a sound pressure level
Set human hearing 20uPa as 0
Added a logarithmic scale

Question 23

Give the Dezibel formula.

Answer 23

20* log10 (Pm/Pr)

In dB SPL

Question 24

What does Pm (dezibel formula) stand for ?

Answer 24

Measured sound pressure

Question 25

What does Pr (dezibel formula) stand for ?

Answer 25

Threshold sound pressure,

20 uPa

Question 26

Give the human hearing threshold on the Decibel scale.

Answer 26

0 dB SPL

Question 27

What is the smallest change (in sound) we can perceive as being different ?

Answer 27

1 dB

Question 28

What is the numerical change in pressure level that occurs when a sound gets half as loud when its pressure halves ?

Answer 28

• 6 dB

Question 29

What is the numerical change in pressure level that occurs when a sound gets twice as loud when its pressure doubles ?

Answer 29

+ 6 dB