The Laser 3000 technical reference manual contains a section about the sound chip. It is an "SN76489AN digital complex sound generator" from MOS Technology, Inc. The listed features are:
Apart from what little I know of controlling the mythical sound chip from BASIC, all I really know about the Laser 3000's sound is this:
The Laser 3000 uses the same speaker toggle at $C030 as the Apple ][, for Apple compatibility. This probably doesn't use the sound chip at all.
From doing some PEEKing and POKEing, I have found that memory locations $C068-$C06F definitely have something to do with the sound chip. Unfortunately, the technical reference manual does not explain how to access the chip, so I need to do a lot more PEEKing and POKEing.
The ad from Computer Direct says that the Laser 3000 has "4 Voice, 6 Octave Sound". They're stretching the voices, but I don't know about the range.
Sound is played through the internal speaker. Hopefully the internal speaker is just playing some sort of twisted game with me, and the full high-fidelity sound is available through the monitor connectors.
I haven't really studied what the technical reference manual has to say about the sound chip yet.