# Acourate-Wiki

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Appendix

en:wiki:funktionen:td-functions:reversion

# Reversion

Description:

The pulse is inverted in time. This corresponds to a horizontal reflection. In contrast, there is the “Change Polarity” function which mirrors vertically and thus inverts the amplitude.

Here the time is inverted, thus the impulse is played “backwards”.

Options:

-

Use:

A temporal inversion is primarily used for phase correction / manipulation.

The frequency response remains unaffected, but the phase is inverted as a mirror image.

Example:

We invert the direction of our measurement:

The purely min-phase loudspeaker becomes a purely excess-phase filter. If you convolve or filter the loudspeaker with this reversed pulse, the result is purely linear-phase, i.e. mirror-inverted. This can also be seen here in the inverted phase of both, as curve 2 (green) behaves more or less like a compensation filter:

(in the example above, both pulses were rotated on sample 0)

In practice, however, the filter will be cleaned of amplitude and minphase beforehand in order to correct the pure excess phase distortion of the loudspeaker. This is done with “TD Functions - Extract Phase - Excess Phase” after the impulse has been windowed to a reasonable level beforehand (via Frequency Dependent Window).