Student Paper Competition: Modeling Trumpets and Falcon 9 Flyback Noise

This episode is part two of our interviews with the POMA student paper winners from our meeting in Ottawa. First, we talk with Miranda Jackson (McGill University) about her research regarding modeling the mouthpiece and bells of brass instruments. Next, Mark C. Anderson (Brigham Young University) talks about the noise created by the Falcon 9 boosters as they fly back to Earth and the impact that noise can have on surrounding communities.

Associated papers:
- Miranda Jackson and Gary Scavone. "A comparison of modeled and measured impedance of brass instruments and their mouthpieces and bells." Proc. Mtgs. Acoust. 54, 035004 (2024) https://doi.org/10.1121/2.0001925

- Mark C. Anderson, Kent L. Gee, and Kaylee Nyborg. "Flyback sonic booms from Falcon-9 rockets: Measured data and some considerations for future models." Proc. Mtgs. Acoust. 54, 040005 (2024) https://doi.org/10.1121/2.0001916

Learn more about entering the POMA Student Paper Competition for the Fall 2024 virtual meeting.

Read more from Proceedings of Meetings on Acoustics (POMA).

Learn more about Acoustical Society of America Publications.

Transcript

Kat Setzer  00:06

Welcome to Across Acoustics, the official podcast of the Acoustical Society of America's publications office. On this podcast, we will highlight research from our four publications. I'm your host, Kat Setzer, Editorial Associate for the ASA. 

Kat Setzer  00:37

Today we have the second part of our series of interviews focusing on the student paper competition from the Ottawa meeting. I'm speaking with Miranda Jackson, who authored the paper, "A comparison of modeled and measured impedance of brass instruments in their mouthpieces and bells." Thank you for taking the time to speak with me, Miranda, and congrats on the award. How are you doing?

Miranda Jackson  00:55

I'm fine. Thank you very much for inviting me.

Kat Setzer  00:59

Oh, you're welcome. So first, tell us a bit about your research background.

Miranda Jackson  01:03

Well, I started out in physics with a focus on astronomy at the University of Regina in Regina, Saskatchewan. And back then, I didn't even know there was such a thing as an acoustic specialization, but I was also very much into music, and all of my electives were music. And then when I finished that degree, I continued with my interest in astronomy. I took a master's in experimental cosmology at UBC. Then after that, I completed my first PhD in high energy astrophysics at Columbia University in New York, and I also have a degree in music from the University of Manitoba. Then I did some postdoctoral work in astrophysics. I did research and taught various subjects in physics and astrophysics. And then I moved to Montreal and started my second PhD at McGill in music technology in the Computational Acoustic Modeling Laboratory, or CAML, run by my supervisor, Professor Gary Scavone, which is where I am now. I'm also a student member of the Center for Interdisciplinary Research in Music Media and Technology, also called CIRMMT. My thesis work is funded by the Natural Sciences and Engineering Research Council of Canada, also called NSERC. You might think that this is a very big jump for me from one topic to another, but I just want to say that the analysis of sound signals is very much like the analysis of certain types of astrophysical data, and a lot of the behavior of sound waves is very similar to the behavior of light waves. So my background in astrophysics has prepared me well for my work in acoustics.

Kat Setzer  02:51

Yeah, I was gonna say it does sound like they are incredibly different topics. But when you put it that way, it does make sense, I guess, the transition between the two fields. So what is impedance and how does it affect the playing of brass instruments?

Miranda Jackson  3:04

Well, often you will hear the word impedance as it relates to electricity. It implies that the current that flows through a circuit will be smaller, the greater the impedance. Since current is generally what provides the power in an electrical circuit, impedance reduces the amount of power transmitted by the circuit. 

Miranda Jackson  03:24

Acoustic impedance, though, is the same concept, but with a very different implication for the way instruments work, and most wind instruments in particular. Acoustic impedance is acoustic pressure per unit acoustic volume flow. And by acoustic I mean the time varying components of the pressure and flow in a sound wave. In the acoustic impedance, the pressure is an analog to voltage and the air flow is an analog to current in an electrical circuit. The acoustic impedance quantifies how much pressure variation you need to move the air back and forth inside the air column as the sound wave travels. The steady air pressure in the room and the air flow caused by the player blowing into the instrument are not as important as the back and forth motion of air molecules inside the air column that gives rise to the sound. But unlike an electrical circuit, where, again, the current is what transmits the power, pressure is what we are interested in, because the sound level is determined by pressure amplitude, and not by the amount of air that's going back and forth. So the more pressure, the louder the sound. So when studying wind instruments, we are interested in the input impedance, which is the impedance felt at the input end of an instrument, for example, at the opening of the mouthpiece for brass instruments. The input impedance is a function of frequency and has peaks at particular frequencies. These are the frequencies that can most easily be played on a brass instrument which essentially follows the harmonic series, which is important in music. Of course, this also influences the timbre of the sound of the instrument, which is determined by the relative strengths of the harmonics of the fundamental frequency.

Kat Setzer  05:21

Okay, okay. So you're specifically concerned with the impedance of the mouthpiece and the bell. Why do you think it's important to consider these parts of the instrument separately in models?

Miranda Jackson  05:31

Well, for my instrument, the trumpet, for example, it's mostly cylindrical pipes, which are easy to model. The most complicated parts of the instrument are the mouthpiece, which has a varying geometry and the narrowest part of the instrument, and the bell, which is flared and rapidly expands outwards. It is much more difficult to calculate the impedance of these types of geometries because there are other effects that become more important, such as the propagation of spherical waves rather than the plane waves that are more prominent inside a cylindrical pipe, and the radiation out into the room. Even though the mouthpiece and bell are at opposite ends of the instrument, their shapes together determine the intonation of the instrument and how the sound is radiated into the air. So these components are very important in the acoustic sense and also in the sense that the characteristics of these components go a long way to determining the quality and playability of a musical instrument.

Kat Setzer  06:42

Okay, okay. So what is the goal of this study?

Miranda Jackson  06:46

My goal is to use models and calculation techniques to be able to calculate the impedance of an entire brass instrument just from its geometry. That's my ultimate goal. Instruments have been built essentially the same way for centuries. Even in the present day, instrument makers often have to build an entire instrument before they know how well it will play and what it will sound like. The focus of my work is to allow instrument makers to design instruments and instrument components with a computer and test them before actually manufacturing the instrument. This will make it easier, for example, to design instruments for people with disabilities or injuries who might have unique requirements. It wouldn't be feasible to make multiple prototypes for an instrument when only one copy is ever going to be made for one person. So being able to model how the instrument works without building a physical prototype is important for this type of work.

Kat Setzer  07:48

Oh, yeah, that does sound incredibly helpful. So what were the two models you considered in this study?

Miranda Jackson  07:55

Well, the two calculation techniques that I used are the transfer matrix method and the finite element method. The finite element method uses physical principles and equations, like equations in physics, to calculate what will happen over small time intervals and over small elements of volume as sound travels through an air column. Because this involves a two-dimensional or three-dimensional model, there are a lot of calculations needed for this, and it can take a lot of time. On the other hand, the transfer matrix method is a way to divide the air column into segments that are either cylindrical or conical, and use what we know about how sound travels to require only one calculation per segment. Because this involves a one dimensional model, this method is actually much simpler computationally and takes much less time.

Kat Setzer  08:52

Oh, interesting, interesting. Okay, so how did you characterize the mouthpiece?

Miranda Jackson  08:57

Well, for this paper, I had the geometries of two mouthpieces, which were measured by Christian Bosque, who's an Italian instrument maker who also specializes in mouthpieces. So he was very helpful, and I was able to define general parameters for the shapes of trumpet mouthpieces and fit them to the known geometries that I was sent. Since I own myself one of the mouthpieces, and I'm able to borrow the other from a colleague from the same lab as I'm in, I can also measure their impedances for comparison with the calculations that I can perform, since I have the geometries. And I hope that the same parameterization I came up with will actually work for most other brass instruments as well.

Kat Setzer  09:47

Okay, and then, how did you characterize the bell?

Miranda Jackson  09:51

Well, it's very difficult to measure the geometry of either a mouthpiece or a bell because the shapes are very complex. Also, to measure the impedance of just the bell of a trumpet, I would actually have to cut it off my own instrument, which I definitely did not want to do,

Kat Setzer  10:09

Oh, yeah.

Miranda Jackson  10:11

Therefore, the solution I came up with was to 3d print the shape, so that I would know the geometry to a high precision, and also be able to measure the impedance. So for the bell, I found some measurements of trumpet bell geometry in the literature, and I 3d printed a scale model of the bell using those measurements, and that's what I measured with the impedance probe. That way I had an accurate geometry and a way to measure the impedance, so I could do the calculations, and I can measure the impedance, and I can compare them.

Kat Setzer  10:51

3d printing, it's everywhere. That sounds really interesting. Okay, so when did you end up learning about the load impedance?

Miranda Jackson  11:00

Well, the load impedance is more of a tool than a concept in and of itself. It's more about matching the models to the measured impedance data. That's why it's particularly important for the mouth pieces and bells, since they have such challenging geometry. The load impedance characterizes what's happening on the output end of the component of interest. For example, for the instrument, the load impedance would be given by the radiation from the bell. And for the mouthpiece, the impedance of the rest of the instrument is actually the load impedance, as seen by the mouthpiece. And the load impedance is the just the first step in the calculation of the input impedance. So it's, as I said, it's more of a tool for further calculations, rather than a result in itself.

Kat Setzer  11:55

Okay, okay, what was the most surprising, exciting or interesting aspect of this project for you?

Miranda Jackson  12:03

Well, I have to say, I was very pleasantly surprised when the calculations finally worked and matched both each other and the impedance measurements, because I had been having some trouble. That actually happened not too long before the ASA meeting in Ottawa. So there was an element of luck involved. And I was very, very relieved that I had something interesting to show in my presentation in Ottawa.

Kat Setzer  12:31

That is exciting. It's always nice to have results rather than, you know, like, "I kind of am figuring it out, but I haven't quite gotten there yet." 

Miranda Jackson  12:42

Absolutely.

Kat Setzer  12:43

So what are the next steps in this research?

Miranda Jackson  12:45

Well, right now, I'm working on refining the work in that paper, and I will be doing a another presentation at the online ASA meeting in November. And as I said, my ultimate goal is to model an entire instrument. And to this end, right now, I'm performing a closer examination on my previous results to make sure that the calculations are precise in frequency. And I'm also working with others in the CAML lab to see if the calculations or measurement techniques can be improved at all. I'm also, there's other parts of the trumpet that I need to look at, for example, curved pipes. And the fact that a pipe is curved and not just straight, and how tight the curve is affects the impedance as compared with just a straight pipe, and this is known to affect the intonation. So instrument makers actually compensate for the fact that there's curved pipes by changing the diameter of the curved parts of the pipes, and this work with the curved pipes is particularly important, since brass instruments need to be built with curves for practical reasons. I would also like to refine the method for estimating the geometry just from impedance measurements, because again, it's very difficult to measure complicated geometries, so I'm also working on that. Another challenging part of the brass instrument, along with the mouthpiece, the bell, and curved pipes, is the valves themselves. They also have a very irregular geometry inside them and curved sections, obviously. So it's important to understand how this will affect the acoustical properties and also the way it feels to the player as air flows through the instrument, because the reaction of the player is also very important to how an instrument responds also. On a somewhat related note, I have received a funding award from CIRMMT for a project to develop an active mute for the trumpet. I'm presently working on the physical design and the electronic components. Then will come the software development and testing, and I plan to have a prototype by next spring, which I will demonstrate then.

Kat Setzer  15:23

That's cool. It sounds like you have a lot lined up for yourself. Hopefully your research can eventually help with the design of brass instruments. I wish you the best of luck in your research, and once again, congrats on the award. 

Miranda Jackson  15:35

Well, thank you very much. 

Kat Setzer  15:37

Our next researcher actually touches on a topic that we've heard about in a past Student Paper Competition, which is the noise produced by the Falcon-9 rockets. I'm talking to Mark Anderson about his paper, "Flyback sonic booms from Falcon-9 rockets: Measured data and some considerations for future models." Congratulations on the award, and thanks for taking the time to speak with me. How are you doing?

Mark Anderson  15:57

Great Kat, thanks for having me today on the show.

Kat Setzer  16:01

So first, tell us a bit about your research background.

Mark Anderson  16:04

So my research background goes back to when I was an undergraduate at BYU. I first started working on some compressible fluid flows through pipes. Specifically that was in the context of vacuum-assisted toilets on aircraft. And then I moved to working on sonic booms after a couple years of being in the research group. 

Kat Setzer  16:27

Oh, very cool. I think I remember that  the vacuum toilets noise article that you had in POMA now that I think about it.

Mark Anderson  16:37

Yeah, that that wasn't me that wrote that. That was another student, but--

Kat Setzer  16:41

Oh, okay.

Mark Anderson  16:42

It was a fascinating project. I've never done anything quite like it again.

Kat Setzer  16:48

Yeah, I had never even considered that one. Okay, so onto your current research. Usually we talk about noise made by rockets as they launch, but in your research, you're actually looking at the noise from the boosters as they fall back to Earth after the rocket's ascent. Why?

Mark Anderson  17:05

So typically, you're right. We're mostly concerned about rockets as they lift off, and that's because most rockets never actually come back to land. They're typically... After their fuel is spent, the parts of the rocket that are done being used drop into the ocean, never to be seen again. But in recent times, we've started to get more designs for reusable rockets. The foremost among them is the Falcon-9 rocket, produced by SpaceX. And this rocket flies up to about, you know, 100 kilometers or so, before separating from the second stage. And then the booster stage, which is about the last, or the lower two thirds of the rocket, actually flips around and lights its engines again, and can come back and land back near the same place where it launched from. And so you've got this 40-meter-long, blunt booster falling at supersonic speeds through the atmosphere towards the ground. And what that does is it creates a sonic boom, because anything that's traveling faster than the speed of sound will be continuously generating a sonic boom. And what we found is that this sonic boom can matter almost as much, if not more, than the actual launch when we talk about acoustics in the far field. So that comes in terms of peak pressure, but also total sound exposure, depending on where you are relative to the launch and landing facilities. And so if you've got a reusable rocket, or if you have an application where you want to, you know, land the rocket somewhere where you didn't launch it. Let's say you want to carry supplies around the world, or something like that; the sonic boom actually can be your dominant noise consideration.

Kat Setzer  19:11

Oh, interesting. Okay, so what do researchers know about the Falcon-9 booster flyback right now?

Mark Anderson  19:19

Well, first of all, we know that it is a really high-amplitude sonic boom measured on the order of several pounds per square foot. For context, most traditional aircraft sonic booms tend to be on the order of, you know, maybe a couple pounds per square foot of pressure on the ground, but depending on where you're at, for the Falcon-9, you can be upwards of 10 pounds per square foot of pressure. At one particular instance, we measured 16 pounds per square foot of pressure.

Kat Setzer  19:51

Oh, wow.

Mark Anderson  19:52

Which tells you that these are really high-amplitude acoustic events. The other interesting thing is that most sonic booms have two shocks. When a sonic boom is generated, every little protuberance on the aircraft tends to make a shock, and those shocks all merge as the sonic boom propagates, so that you get a front shock and a rear shock. We call that an N wave. You get one shock at the front followed by a linear pressure expansion and then a recompression shock at the end. But the weird thing about the Falcon-9 booster sonic booms are that it has three distinct shocks. And traditionally, we would say, "Okay, that should merge into just two shocks," but it doesn't. And even weirder, when we measure at different distances, you know, everywhere, as close as 300 meters to 25 kilometers from the landing location, we see that those shocks are consistently located at the exact same locations within the sonic boom, and we see no evidence, really, of actual shock coalescence with distance, and that kind of flies in the face of much of what we would traditionally expect from sonic booms.

Kat Setzer  21:12

Ooh. So it's kind of a mystery. 

Mark Anderson  21:14

It is, it is. 

Kat Setzer  21:16

So how did you go about getting measurements of the Falcon-9 booster flyback noise?

Mark Anderson  21:21

It's a lot of traveling. BYU is located in northern Utah, and there's no rocket launches happening there, because rockets tend to launch near the ocean, so that if something goes wrong, you let things fall into the water. But we've made several trips down to Southern California, to Vandenberg Space Force Base, but also to Cape Canaveral and Kennedy Space Center over in Florida for similar rocket launches. And so it's lots of traveling, lots of driving, flying, setting up equipment and all that, over many years of effort produces a substantial data set of these sonic booms.

Kat Setzer  22:06

Oh, okay, okay, sounds like a lot of work.

Mark Anderson  22:10

It definitely is. It takes a whole team of of students to go out and get all the data sets.

Kat Setzer  22:18

Yeah. Well, sounds like a good learning experience, at least. 

Mark Anderson  22:21

Definitely.

Kat Setzer  22:23

So what did you find with regards to the peak pressure and rise time of the fly back noise?

Mark Anderson  22:28

So when you take a look at the launch noise from a rocket, if you plot it in decibels as a function of distance, especially if you put that distance scale on a logarithmic scale, you find that the launch noise tends to decay linearly with distance, or log linearly, because we're on a log axis. What we found with the sonic booms are that far away, so, you know, maybe farther than two kilometers or so from the landing location, you get that same linear decay with distance, but everywhere within two kilometers actually gets a plateau of the sonic boom noise. 

Kat Setzer  23:13

Oh! 

Mark Anderson  23:14

And that's interesting, because that tells us that everywhere within about a two-kilometer radius of the landing location experiences the same sonic boom in terms of peak pressure, but also in terms of all of our other sonic boom metrics that we considered in the paper. 

Kat Setzer  23:32

Oh, that's weird. 

Mark Anderson  23:34

That was fascinating. I like to say, you know, depending on your perspective, either everyone within two kilometers wins or loses depends on who you are and what your goals are. It's an important thing to know, because if you want to have personnel around these... let's say that you are landing a rocket for humanitarian or military purposes somewhere in the world, and you want to have personnel nearby, you might initially think, "Oh, I'm 500 meters away. Let me quadruple my distance out to two kilometers away, and that should be a safer acoustical environment," when, in fact, it's essentially equivalent. 

Kat Setzer  24:15

That is so weird. 

Mark Anderson  24:17

That was a really interesting and very practical thing to know. If you know, you're at all concerned about the acoustical environment, and I mean, these are loud. They're not they're not going to knock you off your feet, kind of loud, but we have no idea yet what the effects of repeated exposure are on structures, wildlife. We just have no idea. Yet, we saw a similar trend for all of our metrics, including the rise time as well.

Kat Setzer  24:45

Okay, interesting. So how does the Falcon-9 signature triple boom play into the fly back noise, and why do you think it occurs?

Mark Anderson  24:55

So the triple boom is a defining characteristic of the Falcon-9 sonic booms. Back when the Space Shuttle was landing, consistently, residents near the areas where it would land or fly over would comment frequently on the double boom, the boom-boom, which is typical of most sonic booms, but most people hadn't really had a ton of experience listening to sonic booms. But right when the Falcon-9 booster started landing on land, because they can also land it at sea, on a boat, but when they started landing on land, there were several news articles published and lots of people saying, "Oh, this is different from the Space Shuttle. Why is this different? This has three shocks." And so what that tells us is that people are responding to the fact that this has three shocks. Whether it's damaging to them, we have no idea. But that tells us that it is an important characteristic of the noise, and in modeling efforts, that is something that we should try and get done accurately. And as far as why I think it forms a triple boom, I'm glad you asked, because I'm hoping to submit a journal article manuscript to JASA Express Letters, either late this week or early next week, that delves into several different analyses that all point to the same conclusions for why a triple boom is formed.

Kat Setzer  26:25

Ooh, I'm excited to see that article. 

Mark Anderson  26:28

So that that's exciting. Be excited. I'm excited for it. 

Kat Setzer  26:32

Yeah, totally. How do the sonic booms of the fly back noise compare to other sonic booms in general, and to the Falcon-9 launch noise specifically?

Mark Anderson  26:43

So as far as other sonic booms in general, it depends on how far away you are. A lot of other sonic booms from traditional aircraft tend to have perceived levels, which is a complicated metric, and can be controversial in terms of how relevant it is to, you know, a wide variety of sonic booms, but the perceived level metric that we calculate for normal, you know, horizontal aircraft flight tends to be around 100 to maybe 110 decibels. And if you're up close to the landing location for a Falcon-9, you can expect in the range of 120 to 130 decibels. And every nine dB is approximately a doubling of loudness. So remember that supersonic flight over land was banned because the sonic booms were too loud. People were annoyed by them or worried about damage to property. So these, these sonic booms, if you're within a few kilometers, can be very loud-- but granted, most people aren't that close. You know, that's going to be just personnel people on the military base where it's being launched and landed from. But if you get farther out into the community, you get similar levels of, you know, 110 ish dB at several kilometers, which starts to push into communities. So this is very audible within communities around the launch and landing environments, compared to the launch noise, in particular. If you are farther than two kilometers away from the landing location... Well, let's assume that the launch and landing locations are located right next to each other. If you're more than two kilometers away from the launch and landing facility, the peak over pressure of the sonic boom becomes the highest over pressure event of the entire flight. So people talk about, you know, how loud the launch noise is, but if you're concerned primarily about peak over pressure, which you know, structural damage, or perhaps some species of wildlife might be more concerned with, if you're farther than two kilometers away, it's actually the sonic boom that is going to dominate over the launch noise in terms of the total pressure that is produced. 

Kat Setzer  29:24

Hmm, okay, okay. So how can this increased understanding of flyback noise be used going forward?

Mark Anderson  29:31

So lots of different organizations around the world are designing similar rockets to the SpaceX Falcon-9. They have similar geometries, similar planned flight trajectories, and we expect that in the next few years, we're going to start seeing a multitude of these reusable rockets that are all coming back to land and making these sonic booms. One problem that we have right now is that nobody really has fantastic models of these sonic booms, as far as we can tell. We've read some environmental reports, and this is talked about in the POMA, that suggest that current models are based off of measurements, where the measurements have gone back to update the models. And that works great for one design, but it doesn't give us confidence that we can move that model over to a new design or to another company's rocket or anything like that. And so the goal of being able to model these sonic booms is to have an idea of how loud the booms are going to be before we even launch and land the rocket. Ultimately, it would be fantastic if we could start putting sonic boom mitigation techniques in the design process of these rockets. I believe that that's still fairly far down the road, because most companies are concerned primarily with getting the rockets in the air and reusing them. And I'm okay with that, but eventually, I think that it's going to become a concern enough that people will want to move this into the design process, understanding how loud these booms are going to be in the communities, over the wildlife habitats and everywhere in between.

Kat Setzer  31:21

Okay, yeah, that that makes a lot of sense. What are the next steps for this research?

Mark Anderson  31:26

So the next steps, like I mentioned, are that JASA Express Letters manuscript that I'm submitting this week or early next week on the origin of the triple sonic boom, and that's really exciting. I'm super excited to share that with the world, because nobody really seems to know why that happens. And all the modeling that we've seen, it's all that's reportedareour final metric calculations, and some of the models that they have used are explicitly designed for N-wave, sonic booms, and so that calls, you know, calls into question, how well do we actually understand the physics, and how can we improve that going forward? The other next step is, we've collected a lot of data, and this POMA summarizes three different flights of the Falcon-9 rocket, but we're also working on right now a full JASA manuscript, so it'll be peer-reviewed, that will have no fewer than nine flights, so nine sonic boom events measured at all sorts of different distances, both in California and in Florida, And we can really start to pin down those trends for you know, where do the metrics plateau? What's kind of our uncertainty from launch to launch? And that's another really exciting next step. 

Kat Setzer  32:50

Well, that does sound very exciting. So speaking of exciting, what was the most interesting, exciting or surprising aspect of this research for you?

Mark Anderson  32:56

So the two most exciting things I'd say were one, how loud the sonic boom is compared to the launch noise. I was really surprised to see that it does represent a noise source comparable to the launch. In fact, if you integrate the sound exposure over the entire launch and over the short, you know, half a second sonic boom,they can, depending on your distance, be comparable. The other thing, I know I've talked about this a lot, this is kind of my favorite topic, is nobody seems to know why it's a triple sonic boom. And there are all sorts of explanations you can find on the internet. Most of them make almost no physical sense. And that that happens, you know, we want to provide actual, scientifically backed evidence for why these triple booms are forming, and then hand that over eventually to people whose focus on psychoacoustics, so that they can determine, you know, is it a problem? But looking ahead to the fact that that will probably be a question someday, we want to come with answers at that time, rather than beginning the research then. And so that's the most exciting thing to me, is it's very physics based. It's very much a mystery, trying to figure out exactly why this triple boom happens.

Kat Setzer  34:22

Oh yeah, yeah, that's so cool. I think that, like many folks not in your field of research, I never really considered the noise of boosters flying back to Earth, or how much of an impact that that noise could have on communities who aren't typically exposed to rocket noise, so it's really interesting to learn about that. I wish you the best of luck in your future research. I really hope I get to read that JASA-EL article, and congrats again on the award.

Mark Anderson  34:48

Well, thank you. I appreciate it, and thanks for taking the time today.

Kat Setzer  34:53

Before we wrap up this episode, I’d like to share a couple messages with our listeners. One, if you liked what you heard in this episode, please text it or email it to someone who may enjoy it as well

Kat Setzer  35:02

Second, for any students or mentors listening around the time this episode is airing, we're actually holding another Student Paper Competition for the 185th ASA meeting in Sydney. So students if you're presenting or have presented, depending on when you're listening to this episode, now's the time to submit your POMA. We're accepting papers from all of the technical areas represented by the ASA. Not only will you get the respect of your peers, you'll win $300, and. perhaps the greatest reward of all, the opportunity to appear on this podcast. And if you don't win, this is a great opportunity to boost your CV or resume with an editor-reviewed proceedings paper. The deadline is January 8, 2024. We'll include a link to the submission information on the show notes for this episode. 

Kat Setzer  35:42

Thank you for tuning into Across Acoustics. If you'd like to hear more interviews from our authors about their research, please subscribe and find us on your preferred podcast platform.