Simulation of reverberation in audio signals

A method of introducing reverberation into an electronic signal including first and second audio input signals, comprising the steps of:

• combining the output of a first reverberation means with said second audio input signal and applying the combination of the first reverberation means output signal and the second audio input signal to an input of a second reverberation means;
• combining the output from the second reverberation means with said first audio input signal and applying the combination of the first reverberation means output signal and the second audio input signal to the input of the second reverberation means, thereby to provide recirculation of signals through said first and second reverberation means in a closed loop;
• the loop gain of said closed loop being less than unity;
• responding in each of the first and second reverberation means to the signal applied thereto to provide a similar output signal therefrom which persistently repeats beyond the input signal duration;
• and
• providing an output signal from said closed loop, said output signal thereby having reverberation.

A system for simulating reverberation acoustics in an audio signal comprising:

• at least first and second reverberation means each for responding to an input signal to provide a similar output signal which persistently repeats beyond the input signal duration, with a decay in signal magnitude with each repetition, wherein each of the first and second reverberation means includes;
• a delay line;
• a first reverberation mixer for combining the signal applied as input to the reverberation means with the delay line output signal to provide an output of said first reverberation mixer which is applied to said delay line;
• a second reverberation mixer for combining the reverberation means input signal with the delay line output signal, the output of said second mixer being the reverberation means output signal;
• a high-pass filter between the first reverberation mixer output and the delay line input;
• a low-pass filter between the delay line output and the first reverberation mixer;
• and
• a low-pass filter between the second reverberation mixer output and the reverberation means output;
• means for applying the output signal of said first reverberation means as the input signal of said second reverberation means;
• means for applying the output signal of said second reverberation means as the input signal of said first reverberation means thereby to provide recirculation of signals through said first and second reverberation means to define a closed loop;
• means for providing a loop gain for said closed loop which is less than unity;
• means for mixing said audio signal into said closed loop;
• and
• means for providing an audio output signal from said closed loop.