INT 62 u - FGDRIVER v3.03 - "FG_PLAYING" - DETERMINE WHETHER ASYNC SOUND ACTIVE
        AX = 0075h
Return: AX = sound state (0 = no asynchronous sound, 1 = async sound playing)
Note:   For FGDRIVER v1.10, this function was "FG_INITJOY" (see AX=004Dh);
           "FG_PLAYING" was AX=0091h
SeeAlso: AX=0048h,AX=006Bh,AX=009Eh,AX=00ABh

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