Adaptive Guitar Distortion - Overview 1.2 2006/12/17 15:45:25 US/Central 2006/12/23 13:51:03.564 US/Central Neil K. Narayan narayann@rice.edu Rob Smith rob@rice.edu Brent E. Stephens brents@rice.edu Barron D. Stone barron@rice.edu Neil K. Narayan narayann@rice.edu Rob Smith rob@rice.edu Brent E. Stephens brents@rice.edu Barron D. Stone barron@rice.edu Richard G. Baraniuk richb@rice.edu Mark A. Davenport md@rice.edu

Introduction With the amount of effects that modern guitarists use, it is commonplace to see musicians ranging from amateur to professional running around stage constantly adjusting their settings for optimal sound. One of the manifestations of this inconvenience is in the area of guitar distortion. As avid fans of heavy metal, the guitarists of the group, Neil Narayan and Barron Stone, found themselves constantly adjusting their effects settings when moving between rhythm and lead guitar. Thus the idea of a distortion pedal that could listen to what the guitarist is playing and automatically adjust the distortion based on predefined parameters was born. Through the course of the project, flange and reverb were added to the list of effects to make a more complete package for a live setup.

Design Goals At first, the goal was to implement this filter in real time using National Instruments LabView. Due to time constraints, and the fact that none of the group members knew LabView extensively, a project more along the lines of a proof-of-concept implemented in Matlab was settled upon. The next challenge that presented itself was the problem of how to read and interpret the incoming signals from the guitar. Once this was done, the prospect of implementing the correct distortion settings was fairly straightforward. The group decided that this problem could be broken down to three key areas: (1) determine whether chords or single notes are being played, (2) determine how fast the guitar is being played, (3) apply distortion based on predefined threshold values.