Is that spooky old house full of ghosts, or just infrasound?

Low-frequency noises that humans can feel, but not hear, may be behind the spooky feeling of old houses—and serve as a warning to animals.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:03Flora Lichtman?

  Hey, it's Flora and you're listening to Science Friday. Old creepy houses are a horror cliche, but why? Why do old abandoned houses freak us out? My next guest has a theory and it has to do with a rumble that you cannot hear, but is very real. Dr. Rodney Schmaltz, professor of psychology at McEwan University in Edmonton, Alberta, is here to tell us about his new research. He studies pseudoscience. Rodney, welcome to the show.

• 0:34Speaker 01

  Happy to be here.

• 0:36Flora Lichtman?

  Do you think of yourself as a ghostbuster?

• 0:38Speaker 01

  I do not. I am an educator, but I teach a class on scientific skepticism and we do, in fact, go ghost hunting to debunk the tools you see online and on TV. But I would say I do, what I do is a little bit different than ghost busting.

• 0:54Flora Lichtman?

  Do you have an interest in spooky things, spooky houses?

• 0:58Speaker 01

  I'm interested in why people have these experiences. So I haven't seen any good evidence for the paranormal or for ghosts, but I do believe that people are genuinely experiencing something and that's what I'm interested in. What's that something? Why do people feel like they've had these experiences?

• 1:15Flora Lichtman?

  Well, let's get into your study because you had a hypothesis that people are feeling something. What were you testing?

• 1:22Speaker 01

  We were looking at the impact of infrasound. And infrasound is a low-frequency sound below 20 Hz. We can't consciously hear it, but we can feel it. The way I like to describe it is imagine you're at a concert and there's a lot of bass and you kind of feel that tension in your chest and the hair on the back of your neck might go up, but you know what it's from. It's from the music. But imagine a lower level experience like that, maybe not quite as intense, but you can't hear anything. And infrasound is caused by things like in old buildings, there's low-rumbling pipes or could be old boilers as well. It's caused by heavy machinery, traffic, so it's kind of all around us. So in our research, what we did is we brought people into the lab and we exposed them to infrasound or not. And we did that in the presence of relaxing music or more ambient spooky sounds, the

• 2:07Speaker 01

  kind of thing you'd hear in the background of a horror movie. We took a number of measures, including cortisol. And cortisol is a hormone associated with stress. And what we found was that regardless of the type of music you're listening to, be it creepy or relaxing, cortisol levels went up. On top of that, across both conditions, so across both types of music, people rated the music as sadder and they found it less interesting as well. They reported just generally feeling more irritated in the presence of infrasound.

• 2:38Flora Lichtman?

  Hmm, so it's having an effect on us, whether we're cognizant that it's happening or not.

• 2:43Speaker 01

  Exactly, and I think it could at least partially explain some hauntings in that sense. So, as you said, if you walk into an old building and you don't know what infrasound is, which most people don't, you're feeling something, especially if you're going to the basement, there's a really good chance that there's some little rumbling pipes down there or an old boiler. And if the setting is right, so it's dark, it's creepy, you feel something, it's quite reasonable for someone to believe that they've experienced a haunting, when in fact, what they have experienced is an old boiler.

• 3:14Flora Lichtman?

  Did you, did you measure infrasound in old houses?

• 3:18Speaker 01

  That's actually our follow-up study. So, we are looking at that now. We are going to different supposedly haunted locations here in Alberta, and we have control buildings that are not supposedly haunted, and we're looking to see if the infrasound levels are higher in these supposedly haunted places than places that aren't. So, we just got started on that. We've only gone to about four, I think maybe five, locations now. So, it's on its way. We're looking to see if there are any differences there.

• 3:41Flora Lichtman?

  Is it difficult to measure infrasound?

• 3:45Speaker 01

  It is difficult. You need specialized mics for that, and they're quite expensive. But if you want to see if there's some infrasound, what you can do, if you just light a candle or have a lighter, and the flame starts to bend kind of in the middle, that's a sign that there's infrasound. And if it kind of bends and then starts turning almost, it looks like it's turning, that's a good sign there's infrasound as well. So, I won't tell you how much, but at least you'd know that there's a good chance that there's some infrasound present.

• 4:10Flora Lichtman?

  That's also a sign of ghosts.

• 4:12Speaker 01

  The spinning flame does seem ghost-like, but I assure you, it's not. It is caused by infrasound.

• 4:20Flora Lichtman?

  Are we encountering infrasound in other places?

• 4:23Speaker 01

  We are. There's infrasound all around us. Traffic generates infrasound, subways could generate it, heavy machinery. So it's around. One interesting aspect of our study is to also look at it in the context of noise pollution. So is this infrasound impacting people? Now, I don't want to go beyond our data, so I can't definitively say, but what we found was that at least in a five-minute exposure, cortisol levels went up a little bit. Now, it could be the case that when people are exposed to it for longer periods of time, maybe they habituate. Or it could be the case that maybe over longer periods of time that there's this kind of cumulative effect and people just feel some stress. So we know there's some research showing that people tend to feel more stress in urban rather than rural environments, but this wouldn't explain all of that, but maybe it

• 5:08Speaker 01

  would be a small piece of the puzzle, but definitely more research to be done before we can make any claims either way there.

• 5:14Flora Lichtman?

  You know, big picture, tell me about how this fits in with your research generally, this haunted house study.

• 5:21Speaker 01

  Well, I'm interested in why people believe in things that don't have good evidence. So helping people become better consumers of information. And once people believe something, we know it's really hard to change their minds. And part of the reason is that when you tell someone that something is false, say that ghosts don't exist, you've created this cognitive gap. So they've experienced something. It felt ghost-like, and then somebody comes along and says, there's no evidence for ghosts. It's like, well, then what did I experience? So I hope research like this will give people some, at least some pause, think, okay, maybe what I experienced is an old low-rumbling pipe or an old boiler. So what we're doing then is helping fill in that cognitive gap.

• 6:02Speaker 01

  So my colleagues are more interested in kind of in the noise pollution side. I'm more interested in kind of the education side and giving people explanations for supposedly paranormal events.

• 6:13Flora Lichtman?

  Yeah, and taking people's experiences of the world seriously enough to investigate them.

• 6:18Speaker 01

  Absolutely. Like I said, people are experiencing something. It's a genuine feeling. And we know from past research that expectation is a huge driver of experiencing anomalous or paranormal things. So if you've been told a house is haunted and you go into the basement and you feel something, it's very reasonable to think that it is ghostly, when again, it could just be a factor of the environment in an old building.

• 6:43Flora Lichtman?

  Really interesting, Rodney. Thank you for taking us through it.

• 6:45Speaker 01

  Oh, happy to do it.

• 6:47Flora Lichtman?

  Dr. Rodney Schmaltz, professor of psychology at McEwan University. After the break, looking for infrasound in nature, from volcanoes, earthquakes, even asteroids, do not go away.

• 7:04Speaker 02

  Support for Science Friday comes from the William K. Bose Junior Foundation.

• 7:15Flora Lichtman?

  Infrasound isn't just rumbling out of the basements of old spooky buildings. It's all around us. And my next guest studies infrasound in nature, the low, low-frequency groans from volcanoes and earthquakes and even asteroid impacts. Dr. Milton Garces is the director of the Infrasound Laboratory at the University of Hawaii. Milton, welcome to Science Friday.

• 7:38Speaker 03

  Thank you.

• 7:39Flora Lichtman?

  I've heard you describe yourself as a sound hunter. Tell me more.

• 7:44Speaker 03

  There is this zoo of infrasound out there, and most of it we're familiar with. And then there's all these exotic creatures out there. Some of them are known, but reemerge out of hiding occasionally. And some of them have not been heard in a very long time. And when they do emerge, you don't recognize them.

• 8:11Flora Lichtman?

  What are you-- give me an example. What are we talking about?

• 8:14Speaker 03

  Oh, my goodness. One of my favorite sounds, which is so deep that I have failed repeatedly to try to ensonify it, is the sound from the 2022 eruption in Tonga. We hadn't heard a sound like that in over a century, since Krakatau.

• 8:34Speaker 03

  And when it came up, we have a whole generation of scientists that only knew this signature from the lore of it, you know, written in like royal society journals, right? And to see them from old timey paper scratches to recording it digitally and in like in full digital glory, recorded as it goes all around the world, we hadn't seen that in centuries. So for us, it was a moment of awe. Is this what I really think it is?

• 9:10Flora Lichtman?

  Well, where does infrasound show up in nature? Give me some examples.

• 9:14Speaker 03

  Oh, it's everywhere. It's first you first perceive it in your heartbeat of your mother, you know, if you're sitting there breathing, even walking, a lot of our biorhythms are infrasonic in nature, but we kind of, we're just used to them, right? Even at a deeper level, you know, the sound of the ocean, it contains massive amounts of infrasound, right? The air moving around us. And what we've done as a species is our ear does not respond very well to those sounds because there's so much of them. So we are immersed in this inaudible sound field all the time.

• 9:50Flora Lichtman?

  We're immersed in this audible sound field. So we can't hear it, but can we sense it?

• 9:55Speaker 03

  Oh, yes, we can. We can when it exceeds our threshold of comfort.

• 10:08Flora Lichtman?

  Okay.

• 10:08Speaker 03

  We are, we're finely tuned species, right? As soon as infrasound gets a little louder, we perceive it through vibration of our body. And usually when infrasound is loud enough, it leaks into the audio range. So you start hearing as a bass tone, right? And so that's when we begin to sense that as soon as it increases parts are threshold of comfort, there's like, oh, there's something happening. And it can be very unnerving because what generates infrasound is usually bigger and stronger than us, right? We're talking about the forces of nature.

• 10:49Flora Lichtman?

  A volcano, a hurricane, an elephant. Yeah, okay.

• 10:57Speaker 03

  Big things, often moving fast, right? An asteroid doesn't have to be big, but if it's moving really fast, it has a lot of power and it will generate infrasound, right? So all these things that are like big, hot, or fast can radiate infrasound. And when you hear those coming, it's fair warning, right?

• 11:19Flora Lichtman?

  Well, I wanted to ask, is that part of the interest in studying it? Can you use infrasound to predict that a volcano is going to erupt? Or can it tell us about these phenomena in a different way?

• 11:33Speaker 03

  In some ways it can, yes. In fact, one of the most important applications of infrasound is to provide early warning of an ongoing large eruption so that aircraft can deviate from their paths and avoid the ash that comes with it. That is like a very tangible application. And that is basically now in our toolkit for protecting lives and property, right? And so that's one of them. Another application that came very much to the fore with the Tonga eruption in 2022 is if you have a big eruption in the middle of the ocean, it will generate a tsunami.

• 12:19Speaker 03

  And so the sound from the eruption precedes the tsunami by a substantial amount.

• 12:25Flora Lichtman?

  Hmm.

• 12:26Speaker 03

  And that's also early warning.

• 12:29Flora Lichtman?

  Hmm. I mean, how far does infrasound travel?

• 12:33Speaker 03

  If it's big enough, it'll go around the world multiple times. So.

• 12:38Flora Lichtman?

  Wow.

• 12:41Speaker 03

  So yeah, there's that.

• 12:42Flora Lichtman?

  Wow. I mean, so do you have, how do you collect these sounds?

• 12:48Speaker 03

  So at the turn of the century, we deployed the international monitoring system to monitor clandestine nuclear tests, which has an infrasound network of arrays and deployed throughout the whole planet. And so we have global coverage of infrasound at very high quality. These are exquisite sensors that can pick up like almost anything.

• 13:19Flora Lichtman?

  You talked about ensonifying infrasound, so taking infrasounds and making them audible to us. We have a clip of one of your recordings sped up so we can hear it.

• 13:40Flora Lichtman?

  I'm frightened.

• 13:42Speaker 03

  Funny story.

• 13:46Speaker 03

  When I arrived in Hawaii before the turn of the century, I was already an infrasound specialist. I was doing infrasound before it was cool, right? So, so I was like, oh, there's a volcano here. This is awesome. Does it produce infrasound? Everybody told me, no, Kilauea does not produce infrasound. It's like, hmm, that's unlikely. So we made the first basically polished paper of infrasound from Kilauea volcano. And what you're hearing there is Kilauea in one of its many incarnations because it's a dynamic system. And this is what it does all the time. At the time of that recording, it was an open vent. It had been an eruption for over 20 years and that's why it was radiating all the time.

• 14:30Flora Lichtman?

  All the time.

• 14:32Speaker 03

  All the time. Now, now I don't know if you've seen the activity. It's the most predictable is. Ever been like every week now it erupts and it's really cool to observe that. So then opens up and fire fountains and what you hear is a variant of that. Instead, Koik, because it's in a giant caldera, right? So everything rings. So you get this cathedral effect. If you listen to it correctly, right? It takes a lot of effort to ensonify something as grandiose as a volcanic eruption into our very limited response. So the best I can do is stick into the the bass range, you know, like the stand up bass

• 15:12Speaker 03

  range and try to make something that conveys that feeling of of strength, you know, that comes from the sound field.

• 15:21Flora Lichtman?

  Wait, why? Is there some creative license in there? Why is it difficult to ensonify it? I would think you just like, I don't know, type a number in and say, move it on up.

• 15:32Speaker 03

  You would think so, but bit shifting past a few octaves doesn't map very well. You have a lot of artifacts. So the other way you can do is transpose, which is basically of a sound compression and you have you have to do it in a way that doesn't speed up too much because then it's very short. So there is a lot of, there's some thoughts that have to go into that. Nature gives us what they gives us and sometimes this raw sound sound very raw.

• 15:57Speaker 03

  So you have to capture the elements of that sound that make it really special.

• 16:02Flora Lichtman?

  I love that there's an art to this, to cap to to making these inaudible sounds, these secret sounds audible. Do you have a favorite, Milton? A favorite infrasound in sonification?

• 16:14Speaker 03

  You know, the the one that still keeps getting away is that Tonga event. I haven't been able to capture it with that. I I mean, the the central frequency of this is like 30 minutes. It takes so long to just get a cycle on that, right? To transpose that to the audible ranges. It's such a sonic unicorn. I kid you not. It's called the Lamb wave and we haven't seen something like that in like so long that we thought it was mythical, you know? And there it comes and it propagates at the speed of sound and it looks like sound, but it's not really sound. It's a couple acoustic gravity wave as an edge mode. It is so exotic. It is then a sonic unicorn. I love that thing.

• 17:00Flora Lichtman?

  The Sonic Unicorn, Milton. Thank you for introducing us to this. And thank you for being on the show today. I appreciate it.

• 17:07Speaker 03

  You're welcome.

• 17:09Flora Lichtman?

  Dr. Milton Garza is director of the University of Hawaii's Infrasound Laboratory. One last thing before we go. The weather is getting warmer, which means happy hours, porch beers, fun fruity cocktails. And we want to hear from you. What questions do you have about alcohol and what it does to us? Call with your question and tell us the personal story that led you there. 8774 Sci-Fry is our number, 8774 Sci-Fry. This episode was produced by Dee Peterschmidt. If it raps your worlds, leave us a review. Thank you for listening. I'm Flora Linkman.