Chapter 5 Flashcards
You record a signal and decide to use a sampling rate of 21,209 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.)
10,605Hz
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 ____(independent or dependent) variable, which is ____ , into discrete form.
independent, time
What are two examples of an acoustic transducer?
microphone and headphones
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 decrease the file size, you should ___(increase or decrease) the sampling rate and ____ (increase or decrease) the bit depth
decrease, descrease
Analog to digital conversion (ADC) involves two independent processes, referred to as ____ and _____
quantization and sampling
A continuous variable, such as time or amplitude, can potentially take on an infinite number of values. (T or F)
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
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 ___(small or large) 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 _____(smaller or greater) than half the sampling rate.
greater
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.)
- 1000Hz
- 4000Hz
- 9000Hz
- 17000Hz
- 22050Hz
- 44100Hz
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.
22,050 and 22,050
The process of converting a continuous to a discrete signal is called ______.
ADC, A to D, Analog to Digital Conversion
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 and 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. (T or F)
true
For microphones indented to record speech, the magnitude of the frequency response in dB is usually the highest around ________ kHz.
5
