Vowel Lab I: Source/Filter Vowel Models

So far, we’ve been considering filters as systems that we design and then apply to signals to achieve a desired affect. However, filtering is something that occurs everywhere, without the intervention of a human filter designer. At sunset, the light of the sun is filtered by the atmosphere, often yielding a spectacular array of colors. A concert hall filters the sound of an orchestra before it reaches your ear, coloring the sound and adding pleasing effects like reverberation. Even our own head, shoulders, and ears form a pair of filters that allows us to localize sounds in space. Quite often, we wish to recreate these filtering effects so that we can study them or apply them in different situations. One way to do this is to model these “natural” filters using simple digital filters. That is, if we can measure the response of a particular system, we would often like to design a filter that has the same (or a similar) response. In this lab, we will apply such system modeling to the signals produced when speaking vowels.