A simple audio filter can be identified by the location of its poles and zeros on the complex plane. The aim of this project is to develop an iPhone (TM) application for the purpose of demonstrating the effects of the placement of poles and zeros on the properties of the resulting filter. The application should allow the user interactively to place or modify the poles and zeros, plot/update the corresponding frequency response of the filter, and permit the user to apply the filter to audio signals and hear their effect. Requirements: Knowledge of discrete signal processing (6th semester Signaux et systèmes II or equivalent) and familiarity with or willingness independently to learn programming in Objective-C.