Interesting thread, and I'll probably end up repeating what's already been said, but....
I think all experiences benefit from being augmented by a soundtrack, and UE is no exception. As a matter of course, exploring isn't usually directly accompanied by this soundtrack (with the exception of drains on the rare occasion that I actually remember to pack my waterproof Bluetooth speaker). However, I think that the character and intensity of many UE experiences, and the way we reminisce to relive them after the event, is sometimes best evoked by particular sounds or soundscapes.
All explores have their own associated ambient noise - whether it's the hum of industry, the white noise of water running in a drain, the bird song in an early morning derp or the jarring scream of an unexpected alarm. So we go and we take photos, but that's only capturing one dimension of the experience. Whilst music won't directly replicate the sonic experience of a place, it might help to generate an associated mood. Music is an emotional thing, isn't it? And, as has been noted, it's also a personal, subjective thing, so everyone's associations and tastes will inevitably differ.
For what it's worth, my musical associations are also usually electronic and / or instrumental. Here's a short and non-definitive list of albums that come to mind.
- Tim Hecker - Ravedeath 1972
- Aphex Twin - Selected Ambient Works
- Guy Andrews - Our Spaces
- Bicep - Bicep
- Loscil - Monument Builders
- Godspeed You! Black Emperor- F sharp, A sharp, Infinity (note that Godspeed also have their own tenuous UE link via the soundtrack of the film 28 Days Later)
- Ben Frost - The Centre Cannot Hold
- Burial - Burial
That's enough w(h)ack from me.