Don't speakers/mics tend to have a built-in cutoff? I've played with generating higher and higher frequencies before, and I was able to hear it up to 18kHz. That's probably hitting the high range of my own hearing, but there was an audible pop when the speakers started playing that frequency. The sound card seemed to simply refuse to play that high.
I suppose the malware could be working at a low enough level to override a cutoff in the sound card's firmware. But then wouldn't it have to implement drivers for almost every kind of sound card in existence?
I suppose the malware could be working at a low enough level to override a cutoff in the sound card's firmware. But then wouldn't it have to implement drivers for almost every kind of sound card in existence?