One night two years ago, Terrence Henry (devout KUT listeners will probably remember him) was at home during SXSW when he felt his floorboards start to vibrate.

“I stepped outside, and it sounded like there was a concert happening a couple blocks away. I could hear the bass. I could hear the lyrics," he said. "After a little bit of research, we determined it was Snoop Dogg."

The rapper was performing at Stubb's downtown that night—more than two miles from Terrence's house in Hyde Park.

“The first time it happened I thought maybe someone was having a party, or maybe someone was driving by with a tricked-out bass," he said.

But then he realized the sound was coming from downtown. And his neighbors could hear it, too.

Terrence's neighbors say they hear music from downtown during big events like SXSW or Austin City Limits Fest, and occasionally on weekends throughout the year. The city has received complaints about this over the years, though Terrence, and at least some of his neighbors, don't mind the sound.

“We live in Austin, this is a music town," Terrence said. "It’s one of the great things about living here, and it’s a small price to pay, but it’s a fascinating mystery.”

A mystery that Chad Himmel at the Hancock Golf Course could maybe help solve.

The golf course, also more than two miles from downtown, is one of the places city officials say they’ve heard noise from downtown clubs. The issue isn’t necessarily volume as much as low bass frequency.

To explain this, let’s cue some music. Here's the band White Lung performing at Cheer Up Charlies on Red River earlier this week:

White Lung plays Cheer Up Charlies during SXSW 2016.

Himmel said that what sends that bass frequency so far north is a combination of temperature and wind. When it’s warm out, the sun heats up pavement. When the sound hits that pavement, the warmer temperatures make it move faster. And the sound “is being bent or refracted upward.”

That’s where wind comes in. As the sound moves up, the wind pushes it back down to earth. And when the wind is just right, it pushes the sound into the Hyde Park neighborhood, where it sounds more like this:

The same White Lung performance, as heard more than two miles away in Hyde Park.

Himmel says other factors can play a role, too, like Waller Creek. The creek runs up Red River Street through UT’s campus and into Hyde Park.

When there’s water in the creek, the temperature is usually cooler. And the cool temperatures keep the sound in this valley, and channel it toward Hyde Park.

“So I think there’s a subtle funneling effect, but primarily I would suspect it’s more about wind,” Hammel said.

Buildings and elevation also play a role. Sound can bounce off a building and head somewhere else and be stopped by a hill.

Austin officials say they’re aware that noise can travel into these neighborhoods.

“When we first got complaints about noise traveling to Hancock, I was in disbelief. And until I heard it with my own ears I wouldn’t have believed it," said David Murray with the city of Austin’s music office.

“The wind was north-bound, and all the conditions were right to make it happen.”

A few years ago, the city offered music venues low-interest loans for new sound equipment. The goal was to reduce noise outside venues and in residential neighborhoods. Cheer Up Charlies and Stubb's both applied for loans.

Stubb's is right next to Waller Creek, but the club's general manager Ryan Garrett thinks the new system has kept the sound from traveling up north as often. Murray with the city of Austin says as downtown grows, it gets harder to predict how that growth affects the city’s soundscape:

"It’s a dynamic situation as downtown is being built out. A tower went up recently over on 4th, and complaints have increased from a certain condo because it’s reflecting off that building now. So, it keeps us hopping.”

He says new construction like the Dell Medical School could affect how much sound travels to the Hyde Park neighborhood in the future.