Again, paraphrasing Jim Blascovich and Jeremy Bailenson in their book Infinite Reality:

In a virtual reality version of a casino, it was “eerily quiet”. They could’t get fully into the experience without sound. Once background and situation-relevant sounds were introduced, the virtual reality became more real.

With software, this should be quite achievable:

• record sound in the location
• identify the sounds that trigger human responses (we block out most)
• create a soundtrack full of randomness

The sound will be contrived but convincing. For VR to work, all of your senses need to be in agreeance.