# Audio Engineering - Digital Audio

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| By Chris_s_brookes
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Chris_s_brookes
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Quizzes Created: 5 | Total Attempts: 3,950
Questions: 15 | Attempts: 2,978

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The primary duty of most sound technicians is to record or reproduce sound using audio equipment. However, they may also be responsible for setting up audio and mixing board equipment for sporting events or artistic productions. Test out what you know about digital audio by taking up the comprehensive test below. All the best!

• 1.

### Which of the following is an accurate description of Bit Depth

• A.

Defines the minimum dynamic range of a track

• B.

States how many samples are taken per second

• C.

States how much data passes per second

• D.

States the number of different values each sample can be

D. States the number of different values each sample can be
Explanation
Bit depth refers to the number of bits used to represent each sample in a digital audio file. It determines the resolution and dynamic range of the audio. A higher bit depth allows for a greater number of possible values for each sample, resulting in a more accurate representation of the original sound. Therefore, the correct answer is "States the number of different values each sample can be."

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• 2.

### If the Bit Depth is 16bit, which of the following statements is true

• A.

There are 16 samples per second

• B.

There are 16 different dynamic levels each sample can be

• C.

Each sample can be any value of representable by 16 1's and 0's

• D.

Bit depth relates to the frequency response

C. Each sample can be any value of representable by 16 1's and 0's
Explanation
If the Bit Depth is 16bit, it means that each sample can be represented by 16 1's and 0's. Bit depth refers to the number of bits used to represent each sample in a digital audio file. In this case, with a 16-bit depth, there are 16 binary digits available to represent the value of each sample. This allows for a wide range of possible values, resulting in a greater dynamic range and more accurate representation of the original audio signal.

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• 3.

### If the bit depth was 8, how many different amplitude levels can be recorded

• A.

8

• B.

16

• C.

128

• D.

256

D. 256
Explanation
If the bit depth is 8, it means that each sample in the recording can have 8 bits of information. Since each bit can have two possible values (0 or 1), the total number of different amplitude levels that can be recorded is 2^8, which equals 256.

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• 4.

### Which of the following make up the settings for a Red-Book Audio CD (pick 4)

• A.

Sample Rate = 44,100hz

• B.

Sample Rate = 48khz

• C.

Bit Depth = 128kb/s

• D.

Bit Depth = 16

• E.

Maximum Length = 74 minutes

• F.

Maximum Number of Tracks = 99

• G.

Minimum Number of Tracks = 3

• H.

Minimum Length = 5minutes

• I.

All tracks in WAV format

A. Sample Rate = 44,100hz
D. Bit Depth = 16
E. Maximum Length = 74 minutes
F. Maximum Number of Tracks = 99
Explanation
The settings for a Red-Book Audio CD include a sample rate of 44,100hz, a bit depth of 16, a maximum length of 74 minutes, and a maximum number of tracks of 99. These settings are specified by the Red Book standard for audio CDs, which ensures compatibility with CD players. The sample rate and bit depth determine the quality of the audio, with 44,100hz being the standard sample rate for audio CDs and 16 being the standard bit depth. The maximum length and maximum number of tracks are limitations set by the Red Book standard to ensure that the CD can be played on any CD player.

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• 5.

### If the sample rate is 48khz which of the following statement is true

• A.

Each sample can be 48,000 different values

• B.

The highest recordable frequency is 48khz

• C.

The recorded wave form is sample 48,000 times per second

• D.

The track is sampled 48 times

C. The recorded wave form is sample 48,000 times per second
Explanation
The correct answer is "The recorded wave form is sampled 48,000 times per second." In a digital audio system, the sample rate determines the number of samples taken per second to represent the analog audio waveform. In this case, with a sample rate of 48kHz, the waveform is sampled 48,000 times per second. This allows for accurate representation of the audio signal and is a common sample rate used in professional audio recording and playback.

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• 6.

### Which of these statements is NOT true:

• A.

Increasing the sample rate increase the range of recordable frequencies

• B.

Increasing the sample rate increases the amount of data required to store the file

• C.

Increasing the sample rate increases the amount of time each wave form is sampled

• D.

Increasing the sample rate increases the range of dynamic levels available

D. Increasing the sample rate increases the range of dynamic levels available
Explanation
The range of dynamic levels (dynamic range) is primarily determined by the bit depth, not the sample rate. Increasing the sample rate does not directly affect the dynamic range; it mainly affects the frequency resolution and fidelity of the recorded audio.

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• 7.

### Which of the following statements is an accurate description of Aliasing

• A.

Occurs as a result of the bit depth being too low

• B.

A "ghost" low frequency is recorded when a frequency above the sample rate is recorded

• C.

A ghost high frequency is recorded when a frequency below half the sample rate

• D.

Can be avoided by using a high-pass filter

C. A ghost high frequency is recorded when a frequency below half the sample rate
Explanation
Aliasing occurs when a frequency below half the sample rate is recorded, resulting in a ghost high frequency. This phenomenon happens because the sampling rate is not sufficient to accurately capture the original signal, causing the higher frequency to be misrepresented as a lower frequency. Using a high-pass filter can help avoid aliasing by removing frequencies below half the sample rate before recording.

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• 8.

### An anti-aliasing filter can be created using which of the following EQ filters

• A.

Band-Pass

• B.

Low Pass

• C.

High Pass

• D.

High Shelf

• E.

Low Shelf

B. Low Pass
Explanation
An anti-aliasing filter is used to prevent aliasing, which is the distortion or artifacts that can occur when a signal is sampled or digitally processed. A low pass filter allows frequencies below a certain cutoff point to pass through while attenuating frequencies above that point. By using a low pass filter as an anti-aliasing filter, it can effectively remove or reduce high-frequency components that may cause aliasing when converting analog signals to digital or during digital signal processing.

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• 9.

### Which of the following statements is true regarding in relation to the Niquist Theory:

• A.

To avoid aliasing, the highest frequency must be half the sample rate

• B.

To avoid aliasing, the highest frequency must be double the sample rate

• C.

To record the wave form accurately, the highest frequency must be half the sample rate

• D.

To record the wave form accurately, the highest frequency must be double the sample rate

A. To avoid aliasing, the highest frequency must be half the sample rate
Explanation
To avoid aliasing, the highest frequency must be half the sample rate according to the Nyquist Theory. This theory states that in order to accurately record a waveform without distortion, the highest frequency present in the signal must be sampled at least twice per cycle. Therefore, the sample rate must be at least twice the highest frequency to prevent aliasing, where higher frequencies are incorrectly represented as lower frequencies. By setting the highest frequency to be half the sample rate, the Nyquist Theory ensures that the signal is properly sampled and avoids aliasing.

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• 10.

### What is the minimum amount of times that a wave form must be sampled in order to be replayed at the correct frequency accuracy

• A.

1

• B.

2

• C.

3

• D.

4

D. 4
Explanation
In order to accurately replay a wave form at the correct frequency, it must be sampled at least twice the frequency of the wave. This is known as the Nyquist-Shannon sampling theorem. Therefore, the minimum amount of times a wave form must be sampled is twice the frequency, which is represented by option 4.

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• 11.

### If the sample rate is 48khz, what is the highest frequency which could be recorded without aliasing occuring.

• A.

96khz

• B.

48khz

• C.

24khz

• D.

24hz

C. 24khz
Explanation
The highest frequency that can be recorded without aliasing occurring is equal to half of the sample rate. In this case, since the sample rate is 48kHz, the highest frequency that can be recorded without aliasing occurring is 24kHz.

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• 12.

### Niquist theory applies to what kind of recording:

• A.

Digital Audio

• B.

MIDI

• C.

Analogue Audio

• D.

Kinetic Energy

A. Digital Audio
Explanation
Niquist theory applies to Digital Audio. This theory states that in order to accurately capture and reproduce sound, the sampling rate must be at least twice the highest frequency present in the audio signal. This ensures that all the necessary information is captured and there is no loss of quality during the recording and playback process. MIDI and Analogue Audio do not directly relate to Niquist theory, and Kinetic Energy is unrelated to audio recording.

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• 13.

### Which of the following signals paths would be an accurate possible chain of events for Analogue to Digital Conversion

• A.

Analogue Signal > High Pass Filter > A/D Converter > Digital Signal

• B.

Digital Signal > D/A Converter > Analogue Signal > Amp > Speaker > Audible Signal

• C.

Digital Signal > A/D Converter > Analogue Signal > Amp > Speaker > Audible Signal

• D.

Audible Signal > Microphone > Analogue Signal > Low Pass Filter > A/D Converter > Digital Signal

D. Audible Signal > Microphone > Analogue Signal > Low Pass Filter > A/D Converter > Digital Signal
Explanation
The given correct answer is an accurate possible chain of events for Analogue to Digital Conversion. It starts with the Audible Signal, which is captured by a Microphone and converted into an Analogue Signal. The Analogue Signal then goes through a Low Pass Filter to remove any unwanted high-frequency components. After that, it is converted into a Digital Signal using an A/D Converter, which represents the continuous Analogue Signal as discrete digital values. Therefore, the chain of events provided in the answer accurately represents the process of converting an Audible Signal into a Digital Signal through Analogue to Digital Conversion.

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• 14.

### Which of the following statements is NOT true regarding an A/D Converter running at 48khz, 16bit

• A.

Turns an analogue signal into a string of 1's and 0's

• B.

Measures the amplitude of the wave form 48,000 times per second and stores it as a 16bit word

• C.

Measures the frequency of the waveform 48,000 times per second

• D.

It generates 768000 bits per second

C. Measures the frequency of the waveform 48,000 times per second
Explanation
An A/D Converter running at 48kHz, 16bit does not measure the frequency of the waveform 48,000 times per second. Instead, it measures the amplitude of the waveform 48,000 times per second and stores it as a 16bit word. The converter turns the analogue signal into a string of 1's and 0's, generating 768,000 bits per second.

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• 15.

### If the bit depth is 16, however many different levels of amplitude can be recorded

• A.

16

• B.

(2 x 16 =) 32

• C.

(16 to the power of 2 = 16 x 16 =) 256

• D.

(2 to the power of 16 = 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 =) 65, 536