It seems like your browser doesn’t support drawing directly to the page. Unfortunately, that means that you won't be able to use the tuner.
Use a modern brower: Firefox, Opera and Chrome will all do. Unfortunately, Safari is not a modern, standards compliant browser, and will not support the site.
It seems you've discovered a bug. Unfortunately, that means you won’t be able to use the tuner. Perhaps a reload will solve the problem?
Unfortunately, nothing! It's a mistake on my part. If you know me, and have the energy, tell me how it happened, and I'll try get to the root of it.
Either you haven’t allowed permission to access sound, or your browser doesn't support audio access. Either way, the tuner can't work.
If you denied the tuner permission to use audio, go to the browser's page settings (on desktop browsers, usually to the left of the address), give the page permission, and reload it.
If your browser doesn't support audio, you can use a modern brower: Firefox, Opera and Chrome will all do. Unfortunately, Safari is not a modern, standards compliant browser, and will not support the site.