Chapter 6 Flashcards
In analog waveforms, the independent variable (time) can take on a(n) _________ number of time values.
infinite
Suppose you want to record a conversation between two people who are in an airport with lots of other noise. Which of the following is the best microphone response pattern for this application?
cardiod
Suppose you want to record speech in a quiet and controlled location. Which of the following is the best microphone response pattern for this application?
omnidirectional
The Nyquist frequency is _______ the sampling rate.
half of
Downsampling and upsampling are done to improve sound quality.
false
Compressed recordings (e.g., MP3, AAC) should be used for acoustic analysis and maintaining the recording.
false
Match the each current type with its corresponding source.
Alternating Current (AC)
Direct Current (DC)
Wall plug
battery
Suppose you make a recording and you choose the automatic gain control (AGC) option. Choose all of the options below that accurately describe the resulting recording.
- Gain will be variable across the recording time
- The recording will be overmodulated
- The recording can be used to accurately compare how source level changed as a function of time.
- The recording will be peak clipped
Gain will be variable across the recording time
Adjustments to automatic gain control (AGC) occur instantaneously (i.e. without any time lag) when sudden changes in input amplitude occur.
False
Quantization
The process of converting the continuous dependent variable (the amplitude) to a discrete set of values
Sampling theorem
To reconstruct a continuous time signal, the sampling rate should be at least 2 times the maximum frequency in the signal
Gain
change in amp prior to digitization
Saturated recording
the loudest sound recorded under the maximum sound level that the recorder is able to record
To reduce external noise, we could do all of the following EXCEPT:
Use a directional microphone
Use a sound barrier
Move to a sound treated booth
Open window to allow air flow
Open window to allow air flow
When the peak amplitude of a signal is larger than the upper end of a recorder’s dynamic range, this will result in a
___ recording, which means the the recorded waveform will be ___
overmodulated
peak clipped
The MP3 digital file format (file extension .mp3) is best described as which of the following?
compressed lossy
Frequency of the alternating current in North America is…
60 Hz
Select every true statement about Dynamic Range.
- The ratio of the highest to lowest levels a system can process without distortion.
- Dynamic range can be negative in log space.
- Dynamic range is a single value.
- The ratio of the output level to the input level of a system.
- The ratio of the highest to lowest levels a system can process without distortion.
- Dynamic range is a single value.
Sound recordings are typically played back through two loudspeakers. What type of recordings send the identical signal to two loudspeakers?
Mono
