Nonlinear systems, though difficult to analyze from a systems perspective, have somewhat predictable effects that can be roughly evaluated in the frequency domain. Systems that multiply two signals in the time domain, for instance, have pitch shifting effects in the frequency domain. Thus, multiplying the output of an oscillator and any AC signal input will pitch shift the AC signal input.
Using a variable wave shape and frequency oscillator, an input pre-amp stage, a couple transducers, and some clever PCB design, a voice pitch modulator can be designed with a minimal amount of effort. The engineering behind the circuit is simple and easy to execute, and is a fun way of implementing convolution in the frequency domain.
The project will begin with input design and end with output design. The device is done at a high level, but can change at component, PCB, enclosure and target user levels as dictated by group decisions.
The ultimate goal of this project is to develop experience with all stages of the design process, as this experience is invaluable in the real world of engineering.