Sound

Question 1

What does sound need to travel

Answer 1

A medium

Question 2

How is sound produced

Answer 2

Vibration and collision of particles in a medium

Question 3

What is sound

Answer 3

Longitudinal wave: Has wave behavior like refraction, diffraction, and interference

Question 4

Characteristics of a sound wave

Answer 4

Pitch, loudness, music vs noise, hearing sound, intensity of sound, loudness vs intensity: subjective vs objective

Question 5

Pitch

Answer 5

Frequency of a sound wave

Question 6

Loudness

Answer 6

Amplitude of a sound wave

Question 7

Music vs noise

Answer 7

Regular pattern of frequencies vs irregular mixture of frequencies

Question 8

Hearing sound

Answer 8

Human range of hearing is 20Hz-20kHz

Question 9

Infrasonic

Answer 9

Sound waves below 20Hz

Question 10

Ultrasonic

Answer 10

Sound waves above 20kHz

Question 11

Intensity of sound

Answer 11

Amount of energy carried by sound waves (pW/m^2)

Question 12

Loudness vs intensity

Answer 12

Loudness is generally subjective while intensity is objective

Question 13

Echo problem

Answer 13

For an echo to return you have to account for the distance to the object and then the reflection (Δd*2)

Question 14

Doppler effect

Answer 14

Phenomenon of an object approaching you has an increased frequency (pitch), and decreased wavelength (compression), while moving away from you has a decreased frequency (pitch) and an increased wavelength (stretched)

Question 15

Breaking the sound barrier (sonic boom)

Answer 15

Produces auditory and visual waves when something breaks the sound barrier because of the sudden change in pressure & the object moves faster than sound

Question 16

What happens in a two speaker system

Answer 16

Creation of nodal lines (silent points) and anti-nodal lines (loud points)

Question 17

Beats

Answer 17

Full cycle of loudness of variation from loud to soft to loud due to alternating constructive and destructive interference from two sound waves

Question 18

Standing waves

Answer 18

Stationary patterns of vibrations consisting of nodes, anti-nodes, and the loops, produced by interference and phase shifts

Question 19

Phase shifts

Answer 19

Difference between two crests

Question 20

Scientific & musical names of standing waves

Answer 20

1: first harmonic/fundamental

#2: second harmonic/ first overtone
#3: third harmonic/ second overtone
#4: fourth harmonic/third overtone

Question 21

How much space does one loop occupy

Answer 21

Half a wavelength

Question 22

How to determine the speed of a standing wave

Answer 22

Find the wavelength and use it in the equations

Question 23

Application of standing waves – stringed instrument

Answer 23

Change the note by shortening string length which decreases the wavelength

Question 24

Acoustic resonance

Answer 24

The resonance involves sound waves; it occurs when standing wave is produced

Question 25

How to determine the speed of sound in close end air columns

Question 26

Application of air columns – wind instrument