Change frequency of song based on pressure sensor input?

Alright, so I am trying to modify the frequency of a song via a pressure sensor and play it back - say, for example, the sensor is in a persons shoe; the song would go faster or slower depending on how fast they walk.

The attached diagram lets you modify an audio file via a hex switch and play it back thru headphones.
This demo picks up the beat from a song and displays it as an animation.

For a pressure sensor I am exploring this link.

I’m a beginner- how would I, using either as a template, integrate a pressure sensor to achieve this?

Messages Image(1390889555).png

Your picture:
Messages Image(1390889555).png
I think you can count steps from a place on the wearer's body using an accelerometer, as some cell phone apps can do it. It's a kind of beat detection, not impossible with Arduino but not easy.

Looking at the diagram, I'm wondering where the songs would be stored. SD card? Is this a software synth, or will you add a sound player module?

Curious, what is a "hex switch"?

Changing the playback speed of a song generally does not sound too good unless you also adjust the pitch of the audio.