Audapter is a software package for configurable real-time manipulation of acoustic parameters of speech that runs on desktop and laptop computers. It is designed for research on auditory-motor interactions in speech production, but may also be of use for certain speech signal processing applications. The current version of Audapter supports manipulation (i.e., perturbation) of the following acoustic parameters:

1) Formant frequencies (F1 and F2), in both static and time-varying ways

2) Fundamental frequency (F0, or pitch)

3) Local timing, through time-warping

4) Local intensity

5) Global time delay (delayed auditory feedback)

6) Global intensity.

Audapter Matlab code is available here. The Matlab code also requires a 64-bit MEX file.  The Audapter Manual is located here.