Everything you hear here comes from running the cartridge's own sound engine (mueve_el_sonido, 0x9EA3, and pide_un_sonido, 0x9C4A, which hands it the channels; the interrupt calls it at 0x4075) on an emulated Z80, frame by frame at 60 per second, just as the game calls it. What the engine writes to the PSG is turned into sound with an AY-3-8910 (tools/musica.py). Each MP3 is the whole piece up to where it starts again, plus 8 seconds of the repeat fading out; those that do not repeat end where the engine ends.
The PSG writes have been compared frame by frame with those of openMSX (C-BIOS MSX1 japonés). In every frame the PSG ends up the same:
The timbre is not checked: it is a textbook AY-3-8910, not a recording of the emulator. The probes are tools/omsx_psg.tcl and tools/coteja_psg.py.
pide_un_sonido takes the number in A. Below 0x8D it is an effect and uses a single channel, the third; from there up, two or three channels depending on the number. Only pieces the listing asks for with an ld a and that really sound are published; the table also holds nearly silent tracks (0x8B and 0x8C) and effects. The engine never writes the PSG mixer: start-up leaves it set, and here it starts from that same value, 0xB8.
Starting the game (0x9C)
Asked for by estado_8_elige_dificultad (0x4430); lasts 4.3 s.
The tune at 0x43DD (0x99)
Asked for by la rutina de 0x43DB; lasts 5.4 s.
The submode 3 tune (0x93)
Asked for by submodo_3_del_estado_11 y la rutina de 0x42BC; lasts 2.6 s.
The machine calls (0x90)
Asked for by la_maquina_canta (0x56E5) y la rutina de 0x770D; lasts 2.7 s.
Tenpai (0x96)
Asked for by mira_quien_esta_en_tenpai (0x7713); lasts 2.4 s.