An test aiming to measure support for modern "html5" should not award bonus points for non-standard (speech apis)
Webaudio is a W3C standard.
At issue are the speech (sythesis+recognition) API's, not the audio API's. However...
outright rejected features (websql).
In fact it does not award points for it: it is listed, but its inclusion does not award any points. Firefox does not have it and it still gets 35/35 points in that test.
You're right - I was mislead by the fact that the feature is listed as providing 5 points, but that seems to be in error. The same also goes for speech api's incidentally.
The test isn't as bad as it seemed at first glance (though it's unfortunate that it's unclear what counts for what). Nevertheless, it counts proposed and experimental features, and misdetects at least keygen (which doesn't bode well for others), fails to do even basic validation whether a feature is implemented correclty, and it doesn't clearly make the distinction between html5 and the living spec, going so far as to link to the w3c spec for features like datetime inputs, even though that's not in the spec, but is in the whatwg living spec (from which likely later iterations 5.1 will emerge). It largely follows the living spec, but not everywhere (e.g. keygen, as you point out.)
In short: it's still not a good idea to read anything much into these numbers.