Chapter 5 Flashcards
Suppose that you are going to make a digital recording, and you need to keep the digital file size as small as you reasonably can.
All other things being equal (and assuming that you still obey the sampling theorem), in order to ___ the file size, you should decrease the sampling rate and ___ the bit depth.
decrease
decrease
Analog to digital conversion (ADC) involves two independent processes, referred to as
___ and ___.
sampling and quantizing
A continuous variable, such as time or amplitude, can potentially take on an infinite number of values.
True
In a computer system, the smallest unit of data is called bit (a portmanteau of the words “binary digit”). How many different values can 1 bit express?
2 - 0, 1
The number of possible states (or values) that can be encoded in bits is found by 2^n, where n is the number of bits. If we record a waveform and encode (digitize) it using 8 bits, how many discrete amplitude values are available for us to use?
256
When digitizing a signal, as long as the signal amplitude is ___ compared to the least significant bit (LSB), quantization error is equivalent to adding a small amount of random noise to the digitized signal.
large
The Sampling Theorem says that to avoid problems with aliasing when digitizing a signal, your original analog signal cannot contain any frequencies _______.
greater than half the sampling rate
Suppose you are recording a speech sample. Suppose that the highest speech sound you want to record (the “s” sound) contains frequencies up to 8 kHz. According to the sampling theorem, which of the following sampling rates is allowable? (Mark all correct answers.)
1000 Hz
4000 Hz
9000 Hz
17000 Hz
22050 Hz
44100 Hz
17000, 22050, 44100
Suppose you record a signal and you decide to use a sampling rate of 44100 samples per second (44.1 kHz). The Nyquist rate is ____ Hz, and the highest frequency that you can record is _____ Hz.
22050, 22050
The process of converting a continuous to a discrete signal is called ______. Mark all correct answers.
ADC, Analog to Digital conversion, A to D
The frequency of sinusoidal sounds is given in units of Hz. When digitizing signals, the sampling rate is also often described in Hz.
True
What are outcomes of increasing the sampling rate?
Potential encoding of higher frequencies in the signal, usage of more computer memory
Suppose we sample at 1000Hz. To prevent distortion, our anti-aliasing filter must remove all frequencies above what frequency in Hz?
500
Analog waveforms are continuous in time and amplitude.
True
Which of the following are considered a Transducer:
Microphone Pre-amplifier
Microphone
Computer / Laptop
Loudspeaker
Headphones
microphone, loudspeaker, headphones
For microphones indented to record speech, the magnitude of the frequency response in dB is usually the highest around ________ kHz.
5
You record a signal and decide to use a sampling rate of 11,425 Hz. According to the sampling theorem, what is the highest frequency (in Hz) that you can include in your recording? (If necessary, round your answer to the nearest whole number. Do not include the units.)
5,713
If you want to keep your file size as small as possible, you should decrease the bit depth and increase the sampling rate.
False
Analog waveforms are continuous. Sampling converts the ___
variable, which is ___ , into discrete form.
independent, time
Which of the following are considered an acoustic Transducer:
an XLR cable
microphone
headphone
microphone, headphone
