First, it's an enourmous waste of computing resources.
Second, it doesn't even work, since the 'setinterval' is unusable for audio timing.
Third, what's there to show off? So Javascript got a 'PlayWav' function that you call in not so regular intervals depending on buttonstate. Simple beatbox is simple. Could aswell be 30 lines.
The problmem is that it's shaking like it has Parkinson's.
It can be be coded with webaudio with the same effort.
I've researched this in the past and it's nowehere near significant more complexity. In fact, a primitive solution is about the same as a setInterval call.