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Frequency Shift

Constant Frequency Shift


With frequency shifting, a a constant value is added to the frequency of each component of a signal, so that (harmonic) relationships between signal components are not preserved. If a signal is shifted up by 1.5KHz, the resulting signal will have components whose frequencies are 2.5KHz, 3.5KHz, and 6.5KHz. We have seen that the manipulation of time/frequency regions allow to shift portions of spectrum – snippets – instead of transposing them, but this is done unilateraly. In AS, frequency shift also exist as a treatment, and can be applied with a constant value, or dynamically.

Another Aspect of Frequency Shifting

To apply a frequency shift to an open soundfile, choose Treatment/Frequency Shift.

An elementary dialogue window will open.

Dialogue Window

Specify a constant shift value in the prompt

Press OK to validate.


A blue BPF will appear in the sonogram window, with the constant value displayed on the left.

The Inspector window will show :

  • a Frequency Shift label

  • the main transposition parameters of the container – global treatment  :

    • beginning
    • end
    • duration.

The constant value of the BPF is displayed on the left, with a scale and grid corresponding to the maximum and minimum displayed values specified in the Inspector.

Dynamic Frequency Shift

BPF Parametric Values

Once a constant value has been specified, the BPF can be edited like any other BPF.

To modify its parameters, select the first point or add new points. The parametric values will be displayed in the Inspector and can be modified according to the usual procedures

Basic and Detailed Information about BPFs Edition

A horn, playing a 260 Hz C3 is frequency shifted with changing values, which can be in harmonic relationship or not with the fundamental. The sonogram analysis shows that the original harmonic relationship is not preserved. When the value is a multiple of the original F0, the result is rather harmonic. When not, the sound becomes close to the produce of a frequency modulation.

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