Other

Louis A Schwartz

G Burnell Hohl

A method for the simulation of a realistic reverse tape effect, in real time, comprising the steps of detecting the beginning of a note by monitoring the input audio signal to determine when the same exceeds a variable amplitude threshold for a predetermined period of time and initially modulating audio signal gain with a rising exponential, while simultaneously recording the note attack and initial portion of the note decay period in digital memory, and when the input note amplitude envelope has decayed to a predetermined percentage of its peak value, stopping recording and beginning playback of the previously stored portion of the note decay and attack dynamic, in reverse, with a fixed signal gain.

Digital reverse tape effect apparatus

Apparatus for converting an input note signal of the type having a rapid rise and a slow exponential decay into an output note signal which, from the shape of its envelope, appears to be a time reversed version of the input note signal includes a device which forms a normalized envelope signal, En, and a gain modification device which modifies the instantaneous gain applied to the note signal as a function of the instantaneous amplitude of En. Ideally, the function is proportional to the inverse of the square of the instantaneous amplitude of the normalized envelope signal, En. The gain modification device in accordance with a first embodiment includes an analog-to-digital converter fed by En which addresses a ROM lookup table containing data words corresponding to gain amplitudes. In a second embodiment of the gain modification device, the dynamic range of En is divided into regions and current sources are selected for charging a capacitor depending on in which region the instantaneous amplitude of En lies, to select in each region a slope versus time of the instantaneous gain.

Music signal time reverse effect apparatus

Apparatus for converting the relatively rapid rise time, relatively long fall tone envelopes of a music source output to envelopes having relatively long rise time and relatively rapid fall time and for also varying the frequency of the tone in the nature of the Doppler effect of an accellerating source provides the modulation input to cascaded phase and amplitude modulators fed by the music source.

Music signal conversion apparatus

Apparatus for converting the relatively rapid rise time, relatively long fall time tone envelopes of a music source output to envelopes having relatively long rise time and relatively rapid fall time includes a sawtooth relaxation oscillator whose output feeds a modulator which is also fed by the music source. The oscillator is turned on via a transistor switch when the average power of the signal at the output of the modulator exceeds a predetermined reference threshold signal.

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Ansonia, CT, United States of America

Louis A Schwartz