The natural world is filled with sound beyond the range of human hearing. Still, thanks to modern recording technology, scientists and artists are finding new ways to capture and translate hidden soundscapes.
Dr. Brian House, a professor of art at Amherst College, brings listeners into these worlds on his record, “Everyday Infrasound in an Uncertain World.” What follows is a lightly edited transcript of their conversation. Click the audio players below to hear each soundscape.
FILE - A rat leaves its burrow at a New York City park in September 2015.
Listen to rats in New York City
Arun Rath: Let’s start off with a sound that we just heard. Those are rats that sounded more like a whale song. What did you do to the rat sound to enable us to hear this?
Dr. Brian House: What’s fascinating to me is that the rat squeak that we’re familiar with is actually the very lowest sound that a rat makes. Most of rat communication — the happy calls, when they’re talking to their friends, chastising their kids, playing, and even laughing — those sounds are higher frequencies than we’re ordinarily able to hear. So by recording those frequencies with an ultrasonic microphone and then slowing them down, that brings the pitch down into our range of hearing. Then, we can kind of get a sense of what the rats might be saying.
Rath: When you’re saying that they’re making happy sounds or scolding their children, you’re not being metaphorical. This is a side of the rat that we can see because of this sound.
House: That’s right. Rat vocalizations are actually used very commonly in a laboratory setting. So, when we do medical experiments, for example, on rats, scientists know they’re happy if they make these ultrasonic vocalizations. That’s in the lab.
When I learned about this with rats, I wanted to see what rats on the streets of New York City would sound like, and to see if I could actually capture those sounds. It turns out you can hear them using this specialized equipment. They’re making all kinds of vocalizations. Some of them we know from science, some of them we don’t. There are studies underway now by urban ecologists to get a better sense of how rats are communicating with each other in the urban environment.
Rath: Talk a bit more about that with our range of hearing to give us a sense of infrasound, ultrasound, and how much we are missing.
House: So infrasound and ultrasound are both anthropocentric terms, right? Nominally, the range of human hearing is from 20 hertz on the low end to 20,000 hertz on the high end. Now, that’s not really true. People have all kinds of different ranges of hearing. Two ears on one head might have different hearing ranges, and of course, some people don’t hear at all. So there’s a lot of variation among that. Those are kind of the limits of human hearing, I would say.
On the high end, there’s all kinds of mechanical sounds and also the sounds of other animals, rodents, certainly. All creatures kind of perceive those ranges differently depending on how they’re interacting with their environment.
The low end is what I’ve been interested in recently and is the subject of this album. There are massive sounds happening all around us all the time. We’re just not aware of it because we can’t perceive it. These sounds are being transmitted through the atmosphere.
Something that’s really special about these low frequencies is because these wavelengths are so long, they can travel incredible distances. So they’re not only low sounds, they’re distant sounds. It’s just fascinating to me the idea that if we could hear those sounds in our everyday lives, we would be hearing thousands of miles away. We would have a different understanding of the scale of this planet and what’s happening.
Those low sounds traveling through the atmosphere are coming from all of these interesting sources, whether that’s ocean currents, avalanches, wildfires or giant HVAC systems at data centers. It’s a variety of sources that I think are fascinating and that are all kind of entangled with climate change in some way. So, it’s really an understudied and underappreciated soundscape. With this album, I’m trying to bring that into the conversation a little bit so we can experience it in some ways.
Rath: You bring out some of the sounds of the Earth itself. One of the wildest ones is the sound of glaciers.
Listen to the Smeerenburgbreen glacier in Svalbard, Norway
Rath: Now, I might have thought that sound was slowed down, but that’s not what’s going on here, right?
House: These sounds are actually speeded up by a factor of 60. So, an hourlong recording, you hear in a minute. A minute-long recording, you hear it in a second. That changes temporally, but it also raises the pitch when you do that and brings it into our range of hearing.
Rath: Wow, so is that sound of a glacier cracking? It actually takes that long to make that?
House: When I started getting into infrasound and learning about the different phenomena that produce it, I didn’t actually know what this stuff sounded like, right? I would read in the literature [that] glaciers, as they move and as they calve, can create infrasound, but I wanted to hear it. I’m not a scientist, I’m an artist. I work with sound. When I was building the microphones, or what I call macrophones, to be able to record infrasound, I didn’t know what I was hearing.
What I did is I went on a trip up to Svalbard and I set up my equipment right next to a glacier. This was the Smeerenburgbreen glacier in Svalbard, which is a fantastically beautiful sheet of ice. I set it up there and I recorded it as it moved, cracked and did all the things that glaciers do. Then, once I speeded up that recording, I could hear those sounds on some level. You hear all these little pops and granulations. In some way, it’s made an ice cube out of the glacier.
Rath: You talk about how you didn’t know what you were going to get when you set up recordings like this. There are so many things in this record, and that’s also kind of wonderful, where they’re not identified. You don’t know what they are and you’re OK with that.
House: For me, it’s a little bit about the mystery. It’s about the awe, about the fact that we don’t have everything figured out about what’s happening in our atmosphere with this planet.
