Researching Acoustic Data (sept 16)

Question 1

At the peak point of a sound wave, what happens to the air molecules?

Answer 1

They are compressed, at the peak there is the highest air pressure.

Question 2

What does sampling rate determine

Answer 2

it determines how many values (samples) are kept in a second)
if we pick 100 samples from a one-second long signal, our sampling rate is 100hz.

Question 3

What can humans hear up to? (in hz) and what is the default sampling frequency and why?

Answer 3

20,000hz is what the human ear can hear. Sampling rate needs to be double, 44100hz is usually default.

Question 4

What is the bit sample size for typical acoustic analysis?

Answer 4

16 bit

Question 5

What is clipping? What should the gain level be set at.

Answer 5

Clipping refers to the loss of signals from the high and/or low ends because the audio gain was set at a too high level. Gain level should remain around yellow level.

Question 6

Pros/cons to a dynamic microphone (one for karaoke)

Answer 6

• doesnt need power from external source
• less sensitive to details
• better for noisy environments
• are sturdier (harder to break)

Question 7

Pros/cons to condenser microphone

Answer 7

• requires power supply
• more sensitive to details
• good when there’s little background noise
• easy to break

Question 8

Unidirectional vs Omnidirectional Microphone

Answer 8

• Unidirectional
  picks up signals from only one direction
  good for single interviewee setting, especially places with back ground noise
• omnidirectional
  picks up signals from all directions
  good for focus group interviews