Sample rate error

I'm getting a crash when trying to load a 176.4kHz sound (from freedoom WAD). Works find from wadexplorer, though.

Fixed with

``` js
AudioBuffer audioBuffer = audioContext.createBuffer(1,  sample.sampleCount*4, sample.rate*2);
```

But I'm not sure of the impacts of that change (not sure why you put *4 in the first place, either).
