Interactive audio filter design application for the iPhone (TM)

Michael Rusterholz

Semester Master Project

Microengineering section, EPFL

January 2012

Abstract

During this project, an iPhone application has been developed. The goal of this application is to demonstrate the effect of the positions of the poles and zeros on the properties of an audio filter. The application allows to define a real audio filter by placing poles and zeros on the complex plane. It then displays the corresponding phase and amplitude response. In addition, it allows to record up to four minutes of sound and apply the filter to that sound in order to hear the effect. Also, it is possible to apply the filter to a white noise signal.
The app is intended to be a teaching and motivation tool for students of signal processing courses. It has been implemented as a tabbed application with with three views which are shown in the figures 1-3.