XM7 plays fddseek.wav, relay_on.wav and relayoff.wav from its data
directory (linux-sdl/sdl/api_snd2.cpp:155-159, 213-267). The three come
from Win32/ of the XM7 V3.4L77SX+z09 final release archive by PI. and
Ryu Takegami, archived on archive.org as xm7tr_3477sxz09.