Here are the materials from my PyCon 2013 tutorial,  Digital signal processing through speech, hearing, and Python.

Original description:

Why do pianos sound different from guitars? How can we visualize how deafness affects a child's speech? These are signal processing questions, traditionally tackled only by upper-level engineering students with MATLAB and differential equations; we're going to do it with algebra and basic Python skills. Based on a signal processing class for audiology graduate students, taught by a deaf musician.

I've pulled the code snippets and some graphs into the slides so that you can walk through the entire thing by working through the slide deck (below). You can also find all the code (with many inline comments, and some more details that didn't get into the slides) on github.

Tutorial attendees will note that the vocoder demo is still forthcoming -- I'll make a blog post when that's up and update this post to link to the vocoder demo when the time comes.