This page will consider sound design with Digital Audio Effect (DAFx).

Dynamic Delay
Delay effects usually consist of a delay line, implemented as an audio buffer and a feedback path that allows a proportion of the delayed signal to be fed back to the input of the delay line.  This means that the feedback signal is a direct replication of the original signal, just with a smaller amplitude.  This project will propose and implement a new type of delay plug-in that will allow an additional plug-in to be "inserted" in the delay path.  In this way, the delayed signal can be altered by the inserted plug-in.  This opens up a range of possibilities.  For example, inserting a side-chained compressor in the feedback path.  
If the compressor is side-chained to the audio from the output of the delay line, then the delayed audio will only pass through the feedback path when there is audio.  This effect can be built in a DAW like Cubase, Logic or Pro Tools by routing the audio between the effects using AUX sends and returns. The basic structure that was implemented is shown in the following diagram. 
The following example demonstrate the use of a dynamic delay effect.

Original audio:

Dynamic delay audio: