Factor 5 just recently posted the details about its sound system, MusyX for GBA on their website.
Factor 5 just recently posted the specifications for MusyX for GBA on their website.
Word on the block is that the sound system for GBA is significantly better than the sound system for GB or GBC, and equals or exceeds that of the SNES. How does 32 channels, and built-in Dolby Surround (with headphones) grab you? Unless Nintendo includes some killer speakers with the GBA, it looks as though playing with headphones on will be the only way to fly (not that your parents would mind!)
Synthesizer
Up to 32 mixed sample voices
Fully supports the synthetic Programmable Sound Generation (PSG) voices from the traditional Game Boy system
Mixes samples in 16 bits to avoid premature clipping artifacts
Uses sample interpolation to reduce sample aliasing noise
Features pulse-width-modulated synthesis
Supports a true stereo delay buffer for reverb effects
Supports surround realtime encoding for psycho-acoustic effects
Uses both dynamic and fixed voice allocation
Fully scalable system architecture allows you to configure the system to meet your specific
application's needs
True 32-bit highly optimized assembler core routines
Sequencer
Uses MIDI-1 files with arbitrary loop points
Ability to dynamically speed up or slow down the speed of the song at run time as well as
from the MIDI master track
Special MIDI controller can affect dynamic voice allocation
Can temporarily freeze song states in order to cue jingles
General
Number of sequenced songs is only limited by Game Pak memory
Up to 16384 samples can be specified
Up to 16384 sound effects can be created
Thanks go to Factor 5 for letting me in on this information!