AudioFrequencyShift

AudioFrequencyShift[audio,freq]

gives audio by shifting the spectrum of audio by freq.

AudioFrequencyShift[audio,freq,mix]

uses mix to control the ratio between the original and shifted audio.

Details and Options

  • AudioFrequencyShift shifts every frequency freq in the input signal to frequency .
  • The frequency freq can be a scalar or a frequency quantity, an Audio object, a pure function, or a TimeSeries.
  • The mixing parameter mix can be any real number between 0 and 1. The default value is 1.
  • With mix=0, only the original signal is returned; with mix=1, only the delayed signal is returned.
  • AudioFrequencyShift accepts a Method option. Possible settings are:
  • "UpperSideband"the spectrum is shifted by freq
    "LowerSideband"the spectrum is reversed and shifted by freq
    "AmplitudeModulation"both effects are present at the same time
  • The absolute amount of shift should be less than half of the Nyquist frequency.

Examples

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Basic Examples  (2)

Shift the spectrum of an audio signal by 1000 Hz:

Plot the power spectrum of the original and shifted signals:

Mix the original signal with the shifted one:

Scope  (5)

Control the ratio between the original and the frequency-shifted signal:

The shift given as a number is assumed to be in hertz:

Use a frequency quantity:

Time-varying frequency shift using a function:

Time-varying frequency shift using a TimeSeries:

Time-varying frequency shift using a control audio signal:

Options  (2)

Method  (2)

AudioFrequencyShift can use three methods:

While "UpperSideband" and "LowerSideband" produce very similar results, "AmplitudeModulation" generates a different sound:

Applications  (2)

Create a chorus effect using a small amount of shift while mixing in the original signal:

Use frequency shifting to produce complex inharmonic sounds:

Use frequency shifting to "tune" drum-like sounds:

Use frequency shifting to "mask" voices:

Properties & Relations  (1)

Shifting harmonically simple signals like sinusoids changes the perceived pitch:

Shifting complex signals alters the harmonic relationships between their components and can produce an inharmonic output:

Possible Issues  (1)

The absolute value of the shift parameter needs to be less than one-quarter of the sample rate:

Increase the sampling frequency of the input to overcome this limitation:

Neat Examples  (2)

Simulate the behavior of an AM radio:

Shift the original signal to a higher frequency:

Reconstruct the original audio:

Time-varying frequency shift using a RandomWalkProcess:

Introduced in 2016
 (11.0)