PT101 - Lesson 1a
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PT101 - Lesson 1a

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Questions and Answers

What is the most recognizable part of a sound in audio production?

  • Frequency
  • Compression phase
  • Amplitude
  • Waveform (correct)

    • Which part of an audio waveform is referred to as the compression phase?

  • The ascending part of the waveform
  • The silent part of the waveform
  • The horizontal line indicating zero energy
  • When energy reaches its peak and then goes back down (correct)

    • What does a sine wave look like?

  • Smooth curve (correct)
  • Sharp spikes
  • Irregular zig-zag
  • Straight line

    • Which common feature do different waveforms share in terms of energy?

    <p>Horizontal line indicating zero energy</p> Signup and view all the answers

    What behavior is seen in all naturally occurring audio waveforms?

    <p>Ascending from the zero energy line</p> Signup and view all the answers

    How would a silent audio waveform appear on a graph?

    <p>Straight horizontal line at zero energy</p> Signup and view all the answers

    What does amplitude refer to in sound waves?

    <p>Energy level</p> Signup and view all the answers

    How are waveforms with greater amplitude represented visually in a waveform?

    <p>Taller</p> Signup and view all the answers

    What is the unit of measurement for amplitude?

    <p>Decibel</p> Signup and view all the answers

    At what range of Decibels does sound become painful for humans?

    <p>120-130 dB</p> Signup and view all the answers

    Which measurement is used to assess the amplitude of sound traveling through the air?

    <p>dB SPL</p> Signup and view all the answers

    What term can be used interchangeably with amplitude?

    <p>Volume</p> Signup and view all the answers

    What does loudness deal with in relation to sound?

    <p>Perceived sound level</p> Signup and view all the answers

    What is needed to properly record or reproduce a sound using digital audio?

    <p>Several samples spaced evenly in time</p> Signup and view all the answers

    Analog-to-digital (A/D) conversion refers to which process in the recording of audio?

    <p><strong>Conversion of sonic to electrical energy</strong></p> Signup and view all the answers

    What is the term used to describe the part of an audio wave where the air pressure increases?

    <p>Compression phase</p> Signup and view all the answers

    What does a sound's waveform represent?

    <p>Tone or timbre</p> Signup and view all the answers

    What is the term used to describe one period of compression followed by one period of rarefaction in a sound wave?

    <p>Frequency cycle</p> Signup and view all the answers

    How is frequency measured in sound waves?

    <p>In cycles per second (Hertz)</p> Signup and view all the answers

    What frequency range is generally considered for human beings?

    <p>20 Hz to 20 kHz</p> Signup and view all the answers

    Which term is used to describe the decrease in high-end frequency sensitivity over time in humans?

    <p>Presbycusis</p> Signup and view all the answers

    What represents a low-frequency sound compared to a high-frequency sound?

    <p>Fewer cycles per second</p> Signup and view all the answers

    What does a sine wave represent in terms of sound?

    <p>'Pure' sound</p> Signup and view all the answers

    'Two cycles of a sine wave' represents what aspect of sound?

    <p>'Temporal' property</p> Signup and view all the answers

    'Different animals can hear different frequencies.' What enables this phenomenon?

    <p>'Adaptation'</p> Signup and view all the answers

    According to the Nyquist-Shannon sampling theorem, how many samples per second are needed to accurately record or reproduce a sound?

    <p>At least twice the highest frequency of the sound</p> Signup and view all the answers

    What happens when there are less than two samples per cycle when recording a sound?

    <p>Lower frequency is created</p> Signup and view all the answers

    What is the Nyquist frequency when recording at a 44.1 kHz sample rate?

    <p>22.05 kHz</p> Signup and view all the answers

    Why is a high-frequency distortion near the Nyquist frequency audible in digital recordings?

    <p>The distortion is within the audible range</p> Signup and view all the answers

    What is the significance of a 16-bit audio in terms of amplitude representation?

    <p>A maximum of 65,536 discrete amplitude levels</p> Signup and view all the answers

    Which bit depth allows for a more accurate measurement of amplitude in digital audio?

    <p>24-bit</p> Signup and view all the answers

    What is the Nyquist frequency when recording at a 96 kHz sample rate?

    <p>48 kHz</p> Signup and view all the answers

    What is the maximum number of amplitude levels represented by 24-bit audio?

    <p>16,777,216</p> Signup and view all the answers

    How does increasing bit depth affect the dynamic range in audio recording?

    <p>Increases the dynamic range</p> Signup and view all the answers

    What is the maximum dynamic range of a 24-bit audio file?

    <p>144 dB</p> Signup and view all the answers

    How does a 24-bit audio file compare to a 16-bit audio file in terms of dynamic range?

    <p>24-bit has a higher dynamic range than 16-bit</p> Signup and view all the answers

    What is the difference in file size between one minute of 16-bit/44.1 kHz mono audio and one minute of 24-bit/44.1 kHz mono audio?

    <p>~3 MB</p> Signup and view all the answers

    What happens to file size when the sample rate is doubled for mono audio files?

    <p>Doubles</p> Signup and view all the answers

    Which bit depth option in Pro Tools is considered substantially different from fixed point depths?

    <p>32-bit float</p> Signup and view all the answers

    What impact do higher sample rates and bit depths have on Digital Audio Workstations?

    <p>Can handle more tracks and plug-ins</p> Signup and view all the answers

    How much storage space does one minute of 32-bit/44.1 kHz mono audio require?

    <p>~10.6 MB</p> Signup and view all the answers

    What valuable resources are recommended for those interested in diving deeper into digital audio science as per the text?

    <p>Digital Domain and Principals of Digital Audio by Ken Pohlmann</p> Signup and view all the answers

    Study Notes

    Audio Basics

    • The three critical parts of audio are:
      • Waveform: the shape of a sound
      • Frequency: the pitch of a sound
      • Amplitude: the energy level of a sound

    Waveform

    • A waveform represents the tone or timbre of a sound
    • Waveforms have a compression phase and a rarefaction phase
    • A compression phase is when the energy increases, and a rarefaction phase is when the energy decreases
    • The combination of compression and rarefaction phases creates a cycle
    • A waveform with a shorter compression phase and a longer rarefaction phase will have a different tone than a waveform with a longer compression phase and a shorter rarefaction phase
    • Examples of waveforms include:
      • Sine wave: a simple and pure sound
      • Square wave: a sound with a more complex waveform
      • Triangle wave: a sound with a triangular waveform

    Frequency

    • Frequency refers to the pitch of a sound
    • It is measured in Hertz (Hz) and represents the number of cycles per second
    • A higher frequency means a higher pitch, while a lower frequency means a lower pitch
    • The human range of hearing is from 20 Hz to 20,000 Hz
    • Different animals can hear different frequencies
    • The frequency range of human hearing can vary depending on age and listening habits

    Amplitude

    • Amplitude refers to the energy level of a sound
    • It is visually represented in a waveform by its height
    • A sound with a greater amplitude will be a taller waveform, while a sound with a lower amplitude will be a shorter waveform
    • Amplitude can be affected by the force of a sound, such as hitting a drum harder or softer
    • The unit of measurement for amplitude is Decibel (dB)
    • The human range of hearing is from 0 dB (silent) to 120-130 dB (painful)

    Audio in the Digital Domain

    • Audio can be recorded and stored on a digital medium
    • The process of converting analog audio to digital audio is called analog-to-digital (A/D) conversion
    • The process of converting digital audio back to analog audio is called digital-to-analog (D/A) conversion

    Samples and Sample Rates

    • A sample is an instantaneous measurement of an audio signal
    • A sample rate is the number of samples taken per second
    • Common sample rates include:
      • 44.1 kHz (44,100 samples per second)
      • 48 kHz (48,000 samples per second)
      • 88.2 kHz (88,200 samples per second)
      • 96 kHz (96,000 samples per second)
    • The sample rate must be at least twice the highest frequency of the sound to accurately record or reproduce it
    • The Nyquist-Shannon sampling theorem states that the sample rate must be at least twice the highest frequency of the sound

    Bit Depth

    • Bit depth refers to the number of bits used to measure the amplitude of a sound
    • Common bit depths include:
      • 16-bit: 65,536 possible amplitude values
      • 24-bit: 16,777,216 possible amplitude values
    • A higher bit depth allows for more accurate measurements of amplitude and a greater dynamic range
    • The formula for calculating the dynamic range of a bit depth is: 6 dB per bit
    • 16-bit audio has a maximum dynamic range of 96 dB, while 24-bit audio has a maximum dynamic range of 144 dB

    The Impact of Sample Rate and Bit Depth on File Size

    • The choices of sample rate and bit depth will influence the file size of a digital audio file
    • A higher sample rate and bit depth will result in a larger file size
    • The following chart lists sample rates, bit depths, and their corresponding file sizes for a mono, one-minute audio file:
      • 44.1 kHz, 16-bit: 5.3 MB
      • 48 kHz, 16-bit: 5.8 MB
      • 88.2 kHz, 16-bit: 10.6 MB
      • 96 kHz, 16-bit: 11.5 MB
      • 176.4 kHz, 16-bit: 21.1 MB
      • 192 kHz, 16-bit: 23.0 MB
      • 44.1 kHz, 24-bit: 7.9 MB
      • 48 kHz, 24-bit: 8.6 MB
      • 88.2 kHz, 24-bit: 15.9 MB
      • 96 kHz, 24-bit: 17.2 MB
      • 176.4 kHz, 24-bit: 31.8 MB
      • 192 kHz, 24-bit: 34.6 MB

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    Description

    Learn about the concept of amplitude in sound waves and how it is visually represented in waveforms. Explore how different amplitudes affect the energy level of sound and the height of waveforms in this informative quiz.

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