I love to graph things. Everything from outside temperature to server room temperature to the number of users on the network to my weight.I just read an article in Make magazine about DIY ECGs, and it got me thinking.. i want to graph more things about my body :)Would a microphone embedded in the bed be able to pick up the heart beats and calculate the BPM? This way I could graph development in resting heart rate over time. The microphone would pick up lots of noise from the person moving around etc.. but that doesn't mather. It only needs to get a few clean heart beats in order to calculate the bpm, right?What hardware and software would be suitable to create something like this?Any ideas?Yeah, of course there are other more traditional ways of measuring heart beat.. but I'm to lazy to do that.. I'd rather spend some time making a fully automagickal system.