Psychoacoustics

Forrestt and Alex from Land F/X sat down to nerd out about psychoacoustics, which is just a fancy term for understanding how our brains handle the noise around us. They chatted about how city noise, like traffic and construction, actually stresses us out and can even lead to heart problems. (The cool part: Sounds from natural sources like water and birds counteract those issues, helping body and mind feel better.) They finished off discussing how to design better spaces using living walls and specific trees to make the world sound less, well, annoying.

Transcript

SPEAKER_01 0:13

Welcome to Overgrown Ideas. My name is Forrest Williams, and with me here today is Alex Zahn.

SPEAKER_00 0:22

Yay, here I am. I'm here with you. How are you doing? I'm doing well. It's good to be here. How are you for it?

SPEAKER_01 0:27

You know what? I'm good. It's raining today, and I kind of like that. I'm in the minority, but I enjoy a rainy day.

SPEAKER_00 0:34

Alex, what do you do at LandFX? I am the developer of our SketchUp plugin, among other things.

SPEAKER_01 0:45

That's right. Other things, as in you were instrumental in the development of our lighting module, which won an award, I might add, at a trade show. Today we are here to talk about psychoacoustics in landscape design. Psychoacoustics specifically is the scientific study of human sound perception and investigating how the brain and auditory system receive, interpret, and process sound waves. There is a lot of movement in this space specifically regarding the negative health impacts of ambient noise of cities, uh cars, transportation, the hustle and bustle. So fortunately, people are actually starting to build really cool solutions in the landscape architecture and even architecture space to help mitigate these issues. Psychoacoustics is near and dear to my heart because I am a formal former professional musician and an avid music lover. Um I believe you are also a musician.

SPEAKER_00 1:58

I am.

SPEAKER_01 1:59

And a music lover. Bam. Um all the cool people are music lovers. I do have some stats here because uh referencing the decibel scales is kind of tricky. Uh most people don't understand the logarithmic nature of it. So let's talk about it. Um, Alex, can you explain the logarithmic nature of decibels?

SPEAKER_00 2:24

The difference between 10 decibels and 20 decibels is different than the diff different than the difference between 20 decibels and 30 decibels. It's a a curved kind of increasingly increasing.

SPEAKER_01 2:42

The difference between 70 and 80 is perceived as double the volume, correct?

SPEAKER_00 2:49

Every every increase of 10 decibels is gonna be a doubling of the perceived volume. Right. Right.

SPEAKER_01 2:58

So it's not just um oh 80 decibels is just 10 ticks more than 70. It's that it's uh actually double of the perceived twice as loud.

SPEAKER_00 3:12

So 80 decibels sounds twice as loud as 70. 90 decibels sounds four times as loud as seventy. Etc. etc.

SPEAKER_01 3:22

So hopefully that's a nice that's a nice baseline. So now we can talk about what some of these uh reference points are, then 70 decibels. That's like washing machines, showers inside of your car at a freeway speed. So there's like a baseline kind of uh ambience city or whatever civilization baseline. 80 decibels is a reference for something like your garbage disposal, you know, a little bit more loud and aggressive. Uh 85 decibels is quoted as if you have prolonged exposure to that, you're going to start having some negative effects on your hearing. 90 decibels, we're talking about motorcycles, blenders, power tools, sports stadiums. If anyone knows of a quiet blender, let me know. Well, right. At the uh at the juice shop, they have those big plastic enclosures they put over the blenders to try to keep the volume down. Have you seen those?

SPEAKER_00 4:29

Uh-huh. Yeah. Yeah. Same, I feel like we'll probably end up talking about those same kind of principles in non-blender applications as well, but covering putting a yeah.

SPEAKER_01 4:41

Yeah. Well, when I was playing uh drums in a church band back in the late 1900s, I was definitely playing behind a plexiglass sound cage.

SPEAKER_00 4:52

Yeah.

SPEAKER_01 4:54

I was way too loud. Speaking of drums, we get up into the 120 range. Then we're talking about loud rock shows. Um, and even like beyond that, we're getting into jet engine range and stuff like that. That's definitely damaging to your hearing, permanent damage at even short exposures. So that's our decibel framework. I hope that helps. Um, I know it helps me because the logarithmic nature of that scale, I always forget about it. And it when you just say, Oh, yeah, it's 80 decibels, and I was like, Oh, yeah, it's just a little bit louder than 70, right? There are some really cool studies that I found uh talking about the negative effects of these sounds in cities on populations and what it's actually correlating to. And then it was talking about heart disease, uh, mental health issues, anxiety and depression and stuff like that. Heart disease. Heart disease was one of them because it uh because it's relating to uh hypertension, the amount of cortisol in your bloodstream from yeah, yeah, isn't that wild?

SPEAKER_00 6:04

I guess that yeah, that checks out.

SPEAKER_01 6:07

Um, but on the flip side, there is some cool studies coming out of places like UCLA talking about sounds that have positive health benefits. Uh these sounds include water sounds and bird sounds. Um, and interestingly, they identified those two affecting people differently, where water sounds have positive physical health outcomes, and bird sounds had positive uh mental health outcomes as far as lowering your stress and like annoyance levels. Yeah, makes sense.

SPEAKER_00 6:44

I thought that was interesting. I think I have a habit of thinking of things like if I was a caveman, yeah, thousands and thousands of thousands of years ago, uh, how would this affect me? Thinking about the water, okay. So, water, I'm thinking this one seems obvious. You're hanging out by a nice little creek or something, you have running fresh water. That seems pretty good to me in a survival sense. Sounds like I can rest and and relax there. Um, the birds as well. The first thing that comes to mind is like, I feel like if you're in a space, caveman mindset. Yeah. If I'm in an open space or something, and I don't hear any birds or little critters around me, something's about to go down. Something's wrong. Yeah. Red flags. Other animals don't feel safe in this space. Maybe I yeah.

SPEAKER_01 7:47

All the birds have vacated because an earthquake is coming. Yeah. Yeah, yeah, really. And on the flip side of that, you take that character, that caveman, and you drop him right in the middle of New York City. You end up with some other problems as well. Yeah, yeah, but the the sound levels alone would terrify them, right? Like, wouldn't even know what to do. In the landscape architecture world, especially I'm thinking of like park design and you know, maybe uh office park and places like that in these public spaces. People are taking that into account. Different things like living walls, acoustic gardens. There's another cool word, biophilic soundscaping that's focusing on natural sounds, water, rustling leaves, bird song. Nice, um, porous pavements and sound absorb absorbing materials, and urban forests, my personal favorite. I always vouch for trees wherever I can. Oh, yeah. It's in my nature. Bioacoustics designing for these systems and using nature. So, one obvious solution is to use plants and trees that birds are attracted to so that they come and hang out in that space more often. Right? Makes sense. No-brainer. A lot of the things that we're talking about today, they they seem obvious when you say it, but before there were studies to prove that this stuff is true, it could be dismissed as woo-woo hippie science, right? But there's studies that prove this stuff is real. Uh-huh. So I think that's important to recognize in these discussions. Um, we're not just talking out of our butts.

SPEAKER_00 9:53

Yeah. Let's definitely link link some of the studies because I I personally as well want to take a look and see how they quantify some of this stuff. Right.

SPEAKER_01 10:02

Like, how do you what's the control group and how do you quantify the positive health benefits of bird song?

SPEAKER_00 10:12

Yeah, exactly. So I'm I'm curious about the the specifics of of those, but I have no doubt about it. I think like the the acoustics of a space and the like we were just saying about the birds too, you might be in a space where your subconscious is saying there's supposed to be birds here, and I'm not hearing them, and you might feel uncomfortable and maybe compelled to leave. Like, I don't want to hang out here much longer, but you might not be consciously realizing it's because I'm not hearing any natural sounds, or because this space is quieter than I feel like it should be.

SPEAKER_01 10:56

It's uh it's a more of a subconscious trigger sometimes. Yeah. Like, you know, the vibes are off. The vibes are off. I don't know why, but I feel it. Yeah. Yep, exactly. There's a cool thing that I discovered uh when I was looking at this, it reminded me are you familiar with the book How Music Works by David Byrne? No, tell me about it. It's a very, very cool book. David Byrne from The Talking Heads, he wrote it, and it's uh it's a dense book, but it's an entertaining read, and it's filled with um scientific correlations of the things that we're talking about right now.

SPEAKER_02 11:34

Yeah.

SPEAKER_01 11:34

Um, but one thing that he pointed to was a study by Bernie Krauss, he's an ecologist, and it's called the Acoustic Niche Hypothesis. And what what it boils down to is Bernie would go out into uh a habitat, say a jungle or a forest environment, and he would make sound recordings and map out the frequencies of all of the animals on a chart, and he would find that all of the different animals stayed within their little pockets of their frequency range, and they don't overlap.

SPEAKER_00 12:10

Oh, yeah.

SPEAKER_01 12:11

Right? So there's a chart, there's um and he and he has the charts in the book, so it's really cool to kind of visualize it, and it will say, you know, here's the this bird song up here, here's like this monkey screech in the middle from this jungle, here's some insect stuff down here. And what they also discovered is that if you take one of these animals away, they were studying in a habitat, and I forget the animal, but one of them went extinct. And then there was a gap in the chart where no animals were communicating. And then over time, animals would evolve to fill that space. Yeah. It was just so fascinating to me, right? It's um highly recommend this book in general. But that was I gotta check that out. But that's a very cool study that kind of talks about you know, sound and balance, and you know, we get those we get the birds going to the parks because we put planted the right trees, and then everybody's happy.

SPEAKER_00 13:15

Yeah, I think probably a lot of people aren't aware that that's um the landscape, pun intended, of how sound works. I mean, same as uh light, right? You have different colors which are different wavelengths of light. You've got red light, really long wavelength, low energy, Roig biv, orange, da-da-da, up to violet, really short wavelength, high energy, and you can think about um, I don't know, maybe there's a weird example. If if we had to communicate with like laser pointers with Morse code or something, okay, and you're in a crowded space and everyone else around you is using red laser pointers and orange and yellow laser pointers, it would be kind of difficult to communicate with someone if you were both also using orange laser pointers. It gets muddy with everyone else. Use a violet laser pointer, and that's gonna stick out a lot more in the space because you're occupying a different space in the in the spectrum. And sound works the same way. We've got low sounds down to I think the lower threshold of human hearing. It's like 20 hertz. So 20 oscillations per second of the air pressure, which sounds fast, but that's like low, low. You feel it more than you hear it. I think elephants do some stuff down there. Um go further up in the spectrum, and you've got faster oscillations all the way up to 20 kilohertz, 20,000 oscillations per second is about as high as we can hear, and that's like mosquito tone territory. A lot of people can't hear up past like 15,000.

SPEAKER_01 15:24

But I know I can't anymore.

SPEAKER_00 15:26

Yeah, it starts to go away, but uh yeah, animals, same thing, they're occupying a certain range in that spectrum. Even even we do that. You go to uh certain bars or or restaurants where the music or the acoustic treatment in the space is designed to carve out a little niche in the um the range of the sound spectrum where um human voice sits. Right. So you don't have conflicting, you can have ambient noise and and music that's filling the rest of the spectrum, but you're leaving a comfortable little space where we can communicate with each other and we're not fighting against the noise.

SPEAKER_01 16:19

Where are these places you speak of? Because I feel like more often than not, when I go to a noisy restaurant, they're not treating the acoustics like that.

SPEAKER_00 16:30

Yeah, you you gotta look around for them. I think it depends on the goal of the space. So some places they just aren't thinking about that and haven't done anything about it. Yeah. Some some spaces you'll go into and you'll think this is intended to be like an intimate place to have a coffee with a friend or something, and it's in this big stone room with no acoustic treatment, and it probably won't last long, and they might close up shop without even realizing that it's because they're asking people to have an intimate moment in the middle of a giant cave. The vibes are off. Yeah, but I think some places you can go and you can look around and see um, you know, they call them clouds, little acoustic material hanging from the ceiling, or even stuff like this, irregular surfaces that break up the reflections. And if you pay attention to it, you can hear it when you're sitting at a table talking to your friend, whether you can hear the conversation two tables over, and the all the bar clatter, and or whether you feel intimate.

SPEAKER_01 17:44

And again, I think it depends on the intention of the space to applying all this knowledge, applying this conversation towards the public space, the outdoor world, your landscape architecture, your office parks, your public parks, uh, living walls, which I love because they're beautiful, but also they have really good sound absorbing qualities. Um, there's a really gorgeous one at the San Francisco Museum of Modern Art. That's the first one that comes to my mind. It's multiple stories tall and it's well maintained. I mean, in San Francisco they have money to maintain a giant living wall and support the arts, so it's kind of a big deal, and it's absolutely gorgeous. And then when you're out on the balcony right in front of the living wall, it is a beautiful space to be in. Uh I can think of the sound is not bouncing around, the sound is not echoing. It's a nice place to sit on a bench, have a break from looking at confusing modern art.

SPEAKER_00 18:56

Yeah, no, I think that kind of thing is great for a space like that. And just like how we were saying, you know, what your intention is for an indoor space kind of applies to outdoor spaces as well, right? If you want a more intimate, relaxing space, a living wall to break up the sound reflections is good. Um versus if you have something like a church or a big auditorium where you want it to feel like you're in this large space, then you don't want to get rid of those echoes. You want to like that is accentuating the the sense of the scale of the space you're in.

SPEAKER_01 19:45

That's a really good point. That is very intentional, especially in large churches. Um Gregorian chants uh were basically written to be performed in those spaces, and it makes the voices sound more angelic. Oh, yeah. Yeah. So yeah, you don't want to dampen all the balls and put in bass traps and sound clouds. That would really ruin uh the performance. Other things that people are using outside is uh obviously some porous pavements and sound absorbing materials. Um I'm thinking of the first thing that comes to my mind for that is the I forget what it's called, the soft-ish squishy grounds on playgrounds. Oh yeah. Those stuff. Yeah. But those are definitely uh have some sorb absorbing qualities.

SPEAKER_00 20:42

I think rule of thumb, softer materials, more sound absorption, irregular surfaces versus flat surfaces, more sound absorption.

SPEAKER_01 20:54

Urban forests, basically just planting more trees, like that goes a long way. Yeah. Which I love. Um and of course, integrating things like natural sounds, flowing water, as we've discussed, bird song. I love this rustling leaves.

SPEAKER_00 21:17

I was just talking to my fiance about this actually, too. The little tangent on that, the difference between different types of trees and plants when it comes to their sonic profile. You can think about uh pine trees, what it sounds like when wind is blowing through pine trees, they have that whispery, oh yeah, airy sound vo versus um oh, I'm not a botanist. Aspen trees. Where they have the those flat leaves and they kind of rustle against each other and have that um it's like shimmery almost. Very different sounds. Yeah. So masking sounds that you don't want treating the acoustics of a space is one thing, but also introducing and adding sounds very intentionally. We talked about certain trees and flowers and things that attract certain birds and what you want to hear.

SPEAKER_01 22:22

Yeah. Um the kind of the kind of plants and trees that will attract specific songbirds. Uh that's a whole niche of the study, which is very fascinating. Music therapy on a tangent. There's some there's some very cool playground musical instrument designs that people have that we see at the trade shows when we go and we see the playground manufacturers, and there's always that one cool booth that has you know the xylophone and they have like the street congas and like all the different things.

SPEAKER_02 22:59

Yeah.

SPEAKER_01 23:00

And I believe uh I think Jeremiah doesn't enjoy those booths because they're very noisy and you get a lot of amateur musicians just making cacophonous sounds, and it's very distracting. It's a terrible way to describe children. I personally enjoy them, but also it's just a lot of people walking over there and going ding ding ding. Oh, that's cool, and then walking away. So yeah. One xylophone that you're yeah, the one note bing, bing, bing, bing, bing.

SPEAKER_00 23:30

I don't know. I'm I'm excited about seeing those. I remember being a kid and the few times that we didn't really have my parents are musicians. Uh it was only like you go to a friend's house and you see their piano and you get to touch it and hearing the just touching the thing, interacting with the thing, and hearing the note, and then you touch another and you hear a different note. Whoa.

SPEAKER_01 23:56

I mean, that's pretty exciting as a child, and probably very instrumental to uh some development. Totally. Yeah. So in favor of the cacophonous playground musical equipment.

SPEAKER_00 24:10

I'm in favor.

SPEAKER_01 24:12

Yes. Let's roll with it. That's good sounds in the soundscape. Absolutely. Listen, Alex, it's uh it's been a fun conversation talking about psychoacoustics. Oh, yeah. I really have enjoyed this, and you have illuminated this conversation with some things that I didn't discover on my research. So thank you very much.

SPEAKER_00 24:36

You're very welcome. Thanks for having me.

SPEAKER_01 24:38

It's fun to talk about. Uh, thanks for tuning in. This is Overgrown Ideas. Make sure, I know this is I know this is stereotypical, but make sure you click like and subscribe, smash that button. Um, it's just the thing we all have to say it now because we uh are slaves to the algorithm. So thank you so much for tuning in, and we will see you in the next one.