SCI0 sound: "The MT-32 always plays channel 9, the MIDI percussion channel" ??

[ZvikaZ]

The SCI0 sound spec says:

The MT-32 always plays channel 9, the MIDI percussion channel, regardless of whether or not the channel is flagged for the device. Other MIDI devices may also do this.

Are we sure that it's true?

This can be demonstrated by SQ3, sound.073
The MT-32 doesn't report using channel 9, but this channel exists, and is used by ADLIB and FB01.

SCICompanion and SCI Resource Viewer report that MT-32 is not using channel 9, as the header supposedly says - but unlike that comment I quoted from spec.

[MusicallyInspired]

The MT-32 by default operates on channels 2-10 (this can be changed to 1-8 + 10). But it always uses channel 10 for percussion.

I assume the sound spec is referring to MIDI channels counting from 0 because that's more programmer-esque (and I believe Ravi's SoundBox tool counts the MIDI channels from 0-15. EDIT: It does).