lecture 2 - exam 1

Question 1

what 2 fundamentals does SHM require

Answer 1

mass & stiffness

Question 2

spring mass system at rest

Answer 2

potential energy is stored in the mass of the system

force is required to displace the mass

Question 3

spring mass system extended

Answer 3

apply an external force

now force is stored as potential energy in the spring

Question 4

spring mass system compressed

Answer 4

restoring force, removal of external force

mass travels back past the equilibrium point

Question 5

spring mass system SHM

Answer 5

when spring compresses = more energy

will cause spring to shoot back out again

& keep repeating until eventually it runs out of momentum

= simple harmonic motion

Question 6

what is the spring mass system in sound production

Answer 6

the air

introducing force into the air causes small pressure variations

results in sound

Question 7

3 main parameters of sine waves

Answer 7

frequency

amplitude

phase

Question 8

amplitude

Answer 8

loudness

measured in dB or mPa

measured base to peak

Question 9

frequency

Answer 9

pitch

measured in Hz (cycles/sec)

Question 10

phase

Answer 10

measured in radians or degrees

plays a major role in localization

Question 11

simple vs complex sine waves

Answer 11

pure tones vs complex sounds

complex sounds are many sine waves added together

Question 12

what do we use to measure sound amplitude

Answer 12

sound pressure level

Question 13

intensity

Answer 13

sound flowing through some area

Question 14

pressure (compared to intensity)

Answer 14

sound at any given point in space

Question 15

intensity & pressure relationship

Answer 15

intensity = pressure^2

Question 16

pressure

Answer 16

pressure = force / area

Pascal

Question 17

larger pressure for a given area means ?

Answer 17

larger froce is being applied

Question 18

same force applied to 2 different areas means ?

Answer 18

different amount of pressure

Question 19

root mean square

Answer 19

used to measure sound when it has varying amplitudes

especially when they are negative & positive values

average would be 0 if you didn’t use the RMS

Question 20

dB scale

Answer 20

way to transform a linear scale to a log scale using a reference value

puts a huge range of values on a scale that is meaningful & simple to interpret

reference value = threshold of human hearing

Question 21

going up by 10 dB

Answer 21

10 times the energy

Question 22

going up by 20 dB

Answer 22

100 times the energy

10x10

Question 23

doubling of SPL

Answer 23

+6 dB

Question 24

octaves example

Answer 24

distance between 100Hz & 200Hz sounds the same as the distance between 2000Hz & 4000Hz

Question 25

A-weighting

Answer 25

used to account for differences in human sensitivity across frequencies

Question 26

threshold of human hearing

Answer 26

20uPa

(micropascals)