80s American movie about a military experiment that opens a gate into an underground realm

Question

I was reading the question "Looking for an American 80's movie about a hazardous accident in an underground lab in the desert" when I was reminded of a combination SF/horror movie that had a very similar premise.

The basic plot was that the military accidentally (or intentionally) drop a missile or other explosive on an island. This explosive opened a gate /cave to a path deep below where another civilisation is based. These "species" looking like pale creatures/humans, with hell-blue eyes and wearing sort of a wig, in baroque style, (like mozart). They're living in a group, can't stand light and break most of the brighter lights. They couldn't stand high sounds (think it was a sonar, the team that was examining the cave and living below) used to scare them.

I remember that the high sound was the cause of the murdering of the examining crew and couple of military guys, because they couldn't stand the irritating frequency.

Answer 1

I think it could be What Waits Below (1985)?

Here is the plot synopsis from Wikipedia:

The US military is running a test for a special type of radio transmitter, to be used to communicate with submarines, in a deep system of underground caves in Central America. When the signal from one of the transmitters suddenly disappears, a team of soldiers led by Major Elbert Stevens (Bottoms) and cave specialists led by Rupert 'Wolf' Wolfsen (Powell) including scientist Leslie Peterson (Blount) are sent in to find out what happened.

Exploring deep underground, they stumble upon a tribe of albino cave-dwellers who have apparently been isolated from the rest of the world for thousands of years. The cave-dwellers are hurt by radio frequencies and are able to see in infra-red frequencies, tracking the explorers by their body heat."

Here is a scene where you can see the pale creatures.