If you’ve ever hiked Utah’s Wasatch Range and stopped dead in your tracks thinking “what in the world was that noise?” then you are in good company. From native Americans to early explorers, and yes, even Brigham Young and his group, all held strong opinions about the sounds echoing off these peaks.

The Wasatch range is basically a giant acoustic experiment, with the mountain range running it for millions of years without human intervention. 

The first thing that strikes Wasatch visitors is that these mountain winds have personality. They murmur through ridge lines, sigh through the pine stands, and occasionally make sounds that give you pause. A brief moment of alertness before you realize it’s just the canyon doing what canyons do. The Wasatch canyons act like enormous funnels, channeling and shaping the air into something almost conversational, as if the mountains are simply reminding you that you’re a guest here. A welcome one.

The Wasatch Front has many parallel canyons spaced relatively close together. The canyons are separated by ridge lines and other terrain. Low frequency sounds like thunder, rockfall, avalanche blasts and distant gunshots can and do travel great distances in those kinds of environments.

Hikers in the Wasatch frequently report hearing sounds that seem to originate from a different canyon entirely. This phenomenon is caused by sound diffracting over or around ridges, then being captured and amplified by a bowl-shaped neighboring canyon.

In many canyons the echoes can sound like human voices in conversation somewhere else in the canyon, when in fact no one is there. Typically the reflections of a creek are reshaped and delayed by the canyon walls. This is common in the Wasatch’s stream cut drainages, where year-round creek noise provides constant source of sound being reflected and distorted.

After dark the noises become even more strange. During the day, the air cools as you go higher. But after sunset, the ground radiates heat rapidly and as the day becomes night, the earth cools down faster than the air above it. This creates a temperature inversion: cool air near the surface with warm air sitting above it. In these circumstances sound waves bend back downward toward Earth so the sound from far away curves back to the surface, meaning you hear things better than usual.

The inversion creates a layer of cold air near the ground where sounds get trapped.

During the day, a shout can echo five or six times in some Wasatch canyons. At night, with the temperate inversion bending the sound back down and together with the down-sloping winds, the effect compounds.

So, when a camper in Big Cottonwood Canyon hears what sounds like voices or a distant wail with no likely source, they are probably hearing real sounds. The mountain isn’t haunted; it is just an extraordinarily good acoustic instrument that gets switched on after dark. 

The Ute people knew this intuitively. They didn’t need the physics explained. They just knew that the mountains speak at night, and they were right.