This is the visualization of language change that I've always wanted to produce! And now that I've made it, there are all sorts of aesthetic things I'd like to change, but c'est la out-of-the-box-tools-from-google!
I should note that the data underlying this graph would not exist but for the sweat, blood and tears of Bill Labov, Ingrid Rosenfelder, a team of undergraduate transcribers, the NSF, and 3 decades' worth of graduate research teams.
Depicted below is data from the in-development Philadelphia Neighborhood Corpus. We have analyzed 235 speakers who were interviewed as part of the Researching the Speech Community course between 1973 and 2010. That gives us dates of birth between 1889 and 1991, a 102 year timespan! Actually, raw data isn't depicted. Rather, it's the smoothing curve that I fit to F1 and F2.
Hit play to watch it go. You can select particular vowels, and toggle on and off trails. You can also adjust how the bubbles are colored in the top right corner.
The particular vowels on display are /ay/ and /ay0/. /ay0/ is the pre-voiceless allophone, a personal favorite, and look at that thing go! I've also split up men and women, since that has been an important factor in this particular change. The other vowels are there just for context, and are held at fixed points.
Not displayed is the extreme uniformity of this change across speakers. This thing is changing fast, and everyone in our corpus is marching along in surprising uniformity. Can you say "speech community" anyone?