From Video Game Music Preservation Foundation Wiki
Night Waves is the background music for the two waves that take place at night, E2M8 and E3M3. The song has a quiet backdrop with a high-pitch melody giving the song an eerie feel. It is tied with Wave Music 4 as being the least used background music. It is also exactly the same length as Wave Music 6, right down to the thousandth of a second.
When using UltraSound as the output device, this song sounds almost identical for both original and lite patch modes.