The Science of AV: Why Math Matters More Than Marketing

So this is an episode where I want you to go ham on the science and the physics of av. Tell us about this story, this problem you were trying to solve and all of the, the equations and the physics behind what you were doing.

lie to you, to this day, we don't understand why. But students will destroy a microphone on a table. They will picket them, they will break them, no matter what level of education we're talking about. It could be graduate students, it could be undergrad, it could be high schoolers. If you put a microphone on a table, it gets destroyed. So we said, okay, we'll do everything in the ceiling. Common practice in our industry is we have what we call voice lift, right?

So there's voice lift and there's voice reinforcement different, mathematically different, scientifically different. The easiest way to think about it is when we're talking voice lift. It's, you know, me and you sitting, we're having a conversation. Okay? So say that comes around 68 DB on average, just conversational audio levels. Well now you're gonna move 30 feet away from me across a room. but I want voice lift only so it still feels conversational.

So if I'm just talking, you know, to the professor for you, your experience will be as if I'm sitting beside you and you're hearing me at that level. So we fast forward, we have a client, they have a classroom, uh, typical auditorium style, tiered seating, um, students in desks and they say, Hey, we want to implement a voice lift system so we can capture, we can stream, we can do all these things in this rooms, an advanced AV over IP system, all the cool things.

So we say, okay, and we start really thinking about the science behind this room and how we're gonna do this. So we're looking at it and I'm saying, Hmm, this is very interesting because it's not acoustically perfect. No space is generally, um, just not what happens when you're building a room. As we start looking into things, I say, hold on, let's pause for a second. Voice lifts, totally doable. Um, but as I'm looking at the surfaces, got windows, some hard surfaces from the desktops.

So this could be a little bit of a challenge. So for everyone out there, you know, if you're gonna do voice lift, PAG/NAG is your friend, right? PAG is potential acoustic gain. Nag is needed, acoustical gain. And as an equation,

you can do, uh, there may be some calculators out there that can do it for you, but basically as you're working through this, you can figure out, okay, is it even possible for me to get the amount of gain I would need out of this microphone into these speakers without the room going into feedback? And if you've ever been out. Tough.

If you watch a football game on tv, as soon as the UMP turns over, there's a microphone and you hear all that squelching, that's feedback for in case you weren't familiar for anyone out there. You don't want that in a classroom. You don't want it in a meeting space. You try to avoid it. So to really pull this off, we start thinking more and more about it. One manufacturer, this suggests I avoid this, uh, they said, Hey Marcus, this is not gonna work in that space. We've already checked it out.

You know, the heights are not good. It's just, it's, we advise you not to do this. I said, okay. I'm always one to listen to others that are, there are lots of people smarter than me out there. I love to get all the feedback. The other part of me says, how do I know I can't do it? Like, are we Sure. So we're talking amongst ourselves in our design team. Um, shout out to all the members of our design team.

Uh, it's great 'cause we can throw out ideas out here and, you know, someone's seen it or done it, so we work together on it. It really got back to just sitting down. Um, I went old fashioned. I kind of got a paper, digital paper. In this case I was on my computer kind of sketching the room, figuring out where are the speakers, figuring out where the microphone's gonna be. Well then back to this P nag equation. I had to calculate, you know, between every speaker, every seated person.

Okay, what's the distance between them and the farthest other person? Where are the speakers located? And there's a great graphic. Uh, one of our manufacturers has a great graphic to really help understand what this looks like and what it does. So the fun part about it is there's also change in height in this equate in in the room, which makes me have to do a calculation from every seated position almost in this room.

So we go back and we're breaking this all down and I'm working with a manufacturer to just double check my math and they say, Marques sure. It looks good. Not super reassuring, but I said, okay. No, I mean, and essentially we end up designing the system where we calculate it all out. We get it into place. We do these, uh, you know, microphone array systems. We have speakers that we end up turning every individual speaker into its own zone.

So those that do mix-minuses will understand that really quickly. Um, so you can send audio out of certain speakers, but not back to its own zone, and it gets, gets wild fast. But imagine a classroom where you have, you know, 18 speakers in the ceiling. Normally they're all one big group, maybe a few zones. Every single speaker is a zone zone. Every load from this array is now routing to a certain area of the room to capture it and now routing out of the other speakers.

And, uh, it took some tweaks and once we were done with it, we brought in the manufacturer remotely. They checked it out. Uh, I was working with one of our field engineers at the time, and we got it dialed in and it's working perfectly. And the client is, you know, over the moon. They love it. Um, there's some, there's some, you know, rules and caveats because again, with the height change.

In the back of the room, if you stand up, you're probably three feet away from the microphone in the front of the room. You're standing up, you're 11 feet away from the nearest microphone. So there's, there's just a lot of math we're doing behind the scenes, um, as far as game structure at every single microphone position, uh, making sure we have the routing correct. And of course, we're mixing in things like. Well, of course we're doing a Dante because why wouldn't you?

You know, we're digital audio all the time, so are we routing it correctly in domain manager? Are we able to capture it back to the, uh, recording studio area where they can actually see all their classrooms? So finish the project off. It's working great. You know, a few tweaks here and there. Just once we can get it actually in use. Get a full students. See it in action, but it's, it's one of the more challenging deployments. And it all came down to math, right?

It just came down to sitting down, sketching it out, calculating it. And there's no way to cheat this, right? People will say, well, you just throw it in AI nowadays. No, you can't. Um, if you're gonna put it in ai, you have to double check every calculation, because in our industry, there are companies that are working on it, and we internally are also working on it. Can I, you know. Build my own agent using the specifications that are unique to our industry. And it's not quite there yet.

So if you really want to be right, you know, even if you do build your own agent, you have to double check all the calculations right now just to make sure it doesn't, you know, go off on a wild goose chase or I think the term is a hallucination. Say it won't, you don't want any hallucinations because that will really throw off your work. Um, but yeah, and it all came down to math because if you read the brochure for these microphones. Oh yeah, you can do Voicelift and it's great.

And they could do all these things and just put 'em anywhere and here are these case studies and, but people missed it. That's the marketing behind the scenes. There is a lot of calculating and making sure that this is gonna work before we actually, you know, just turn this loose to the client, deploy it in the field. What we're trying to do is gonna be successful. And again, at the same time, it has to be easy, right?

We can't have a client need that just levels or turn this one up, turn this one down. You have to be able to put all the automation in place to make sure this room, they walk in and they start talking. It just works. That's it. They don't need to do anything with the audio system. You know, if, uh, if my professor's wearing a lapel mike, I have to calculate for that to make sure that's not gonna interfere with my. Voice lift system. So all these things are happening.

We're applying ducking and all these cool features in Navy. But that's what has to happen because again, as a professor, I'm here to communicate to students. I'm here to teach. That's it. I'm not here to fumble around with connectors or levels at any of that. So that's, that's why it really, really mattered. Math and physics,

they are undefeated. You know, you can bend, you can cheat, you can kind of, you know, edge things right to the edge, but they always matter.

This is not easy, and something that you've talked about before is to bring your team in as early as possible in the process because, um, you need to be thinking about these things in the architectural phase. And even before that, like tell us the dream. Let's sketch it out and figure out what needs to happen. Because you've said before that architects don't, they're not audio engineers, acoustic engineers, like they don't think in terms of the acoustics like you do.

And so I'm, I'm thinking of your, your sketch, uh, correct me if I'm wrong, but what I had in my mind was, you know, in those kids toys, you like put your pencil in the center of this thing. It's got all these like groove teeth and you kinda like move your pencil around and it's got all these like crosshatching and angles and that's what I'm imagining. That's what I'm imagining. So, so talk to us about, uh, where is it like in the phase where you would ideally want to do this on a project?

Because like you said, architects aren't, you know, they're, they're just not thinking in this way. How do you come in on this project to be thinking about how the room would be set up to, because you've gotta put, uh, you know, holes in the wall for cabling and where the speakers will go and the mics will go, and all that kind of stuff. Like, when is the best time to be thinking about this kind of stuff?

Um, but the second we're doing, you know, programming in the architectural phase, you know, getting into schematic design, that's when we wanna be at the table because we have to hear like, what exactly are you trying to do in this space? You know, we have another client. They have a gorgeous, gorgeous office space. Um, they have a conference room. It is really warm. It's, you know, wood and, you know, marble countertops, and you know, all these glass walls.

The problem became because they said, oh yeah, this is our primary conferencing room, and immediately. We said, Hey, when you say conference, we assume you mean team Zoom, Google meet, what have you. Microphones, speakers, hearing people, right? They say Yes. I say, well, Houston, we have a problem. We have to have some way to use acoustic techniques to dampen audio reflections in this space. Because if you, if you build one, and we've gone through this more than one time, right?

We had one where we did a retrofit. It was already built. We walked in. I said, Hey, I, I bet money that none of your, uh. Web based conferencing goes very well. And they said, no, it's pretty awful, Marcus. I said, yeah, yeah. Just looked around and we're like, yeah. Uh, again, physics and math

are, they just are what they are. And, uh, the, the physics and math, once you get the hang of it, you know right away when you see something, you just automatically know it was a glass room again, they had no, no materials to absorb or to re refract or anything. So once the audio, if you think of audio as energy, right? Audio is just energy in space. So when it hits a hard surface. It's gonna reflect.

So now you have these reflections and before that energy can dissipate, how many reflections are you creating in a room? And that's where, you know, the science of acoustics really comes in to understand how do we put carpet down? How do you put what they call, you know, clouds and ceilings, which are panels that can, you know, absorb or refract or do something so you don't have these reflections Because this microphone I'm talking into right now, you know, even if my ears can't hear it.

This microphone does, and as it starts to reflect more and more and more, I guess, to the far side, so to your side of it, it just sounds garbled. And that's why we say, you know, room is 100% beautiful and 100% not usable for the use case. And so how do you.

Is it like the angles of the walls, the materials of the walls, the height of the room? Like, walk us through your thought press. When, when you walk into a space and, and potentially you do have to retrofit. Let's say you're not brought in early on the process. You have to retrofit it. What do you, what are you thinking through when you walk into a room like that?

You inherently do understand when I explain it to you because you know what a reflection is, you see a mirror, so you kind of know, like if you're in your bathroom clapping and you're in front of a a mirror, or if you're in an all glass patio, you hear what's happening as your clap bounces around.

I know about them and there's a certain amount of, uh, surface area that needs to be covered to make sure you can reduce these reflections. And there's something called RT 60, which judges the decay time of audio,

you know, from a burst in a room. These are just, again, they're mission critical because if your audio decay is not happening fast enough, that means the microphone is picking all this up. It sounds garbled, it sounds echoy, it sounds, you know, all these things are happening in your system. As, as soon as I walk up in the room again, if I see glass everywhere, okay, we have a problem. If I see just really hard surfaces, you have a, a giant marble table, you have hardwood flooring.

If you have an extremely high ceiling, um, open ceilings and all that stuff, like, yeah, that's cool. But you know, if I see HVAC ring through the room, if I can hear your hvac. 'cause if I can hear it, your microphone can hear it. So now I'm fighting at the HVAC level. Right. If you have, we've seen rooms where the HVAC level. I literally have an app on my phone so I can always pull a measurement in the room.

Um, but if your HVAC level is above, say, you know, 30 a db, there's actual what's called a noise reduction coefficient that tells you where it should be for whatever your task is. But I've gone into rooms where HVAC is registering, you know, 58, 65 db. Well, if you're already registering HVAC noise in the realm of conversational audio, Houston, we have a problem, right? So as soon as I walk in and hear and I say, Hey.

Before we go any further with your technology, let's have a conversation about your room because, and we caution people all the time, I can't sell you something that's going to fix the acoustic issue that you're facing. So if your HVAC is, oh man, one client, their HVAC was registering probably 68 db, like this is, this is insanity. Like, you know, there's something wrong here. And I think in their case it had a hole or it had something happening. But if you don't fix that.

Now you have to talk and try to be louder than the microphone. But guess what? What am I gonna do? I'm gonna gate the microphone, which is, you know, you do a digital, it's literally what it sounds like a gate. So it opens and closes when a certain amount of levels detected. Am I gonna do that? Well, guess what? When you're talking, it still hears the hvac. People say, oh, I'm gonna use the EQ and filter. You cannot filter out everything.

If you try to filter out everything where you filter out the human voice and now you sound, people say, oh, it sounds tinny. It sounds robotic. Yes, it does. There's too much EQ being applied, right? So as we just walk in the room, we're gauging total height. Uh, is it open ceiling? As I look around, are there reflective materials? Is there anything that's gonna absorb material? How far away are people sitting from the microphone? That's one that gets people all the time.

They'll say, Hey, I'm on the website, and it said that this, you know, all in one bar, it's good for at least 20 feet. And I just kinda laughed. I said, sure, if you had a perfect room, I haven't seen one yet, but if you had one, then it probably could be good If you're furthest. See the person was at 20 feet away. I said, but in reality, and we've actually tested this, we once did a test with, uh, an audio bar, and we marked our floor and we had seats at, you know, 5, 10, 15, 20 feet.

So we could actually capture it in real time in the real room. And you could see how much the drop off was in terms of the audio quality going outbound. It's like, yes, that doesn't, I know that it says that. And the brochure says, and it's a really beautiful brochure. Nice picture shows

And I'm like, but you know, it's one of these major tech brands has one of those bars, you know, it's got a camera on top, it's got the bar, you can do speakers and mics and, and it, the marketing is that, oh yeah man, for a thousand bucks you're gonna fix all of your conferencing problems. And I'm like, this is great. This is a, this is like a no brainer. Uh, I'm glad I didn't purchase it because you're saying the math is more important than the marketing, so, okay.

Because again, if I just walk in and I hear your hvac, I already know that's an issue. I already know that right off the bat before I've done a single measurement. Hey, this is something we have to be cognizant of because keep in mind. The microphone is going to work better than your ears for a lot, especially for a lot of people that have some, you know, hearing loss or what have you.

Microphones don't have that, so they're hearing everything happening in the room from the, if you have microphones in your desk, you know why we don't do them? You have the, the table tapper. The person in the meeting that's tapping the table, they're ruffling the, the papers, uh, snack time. I wanna open my bag of chips. All of that is going into the microphone. So it's just like, Hey, let's move them up into the ceiling. Okay, well, is your ceiling at nine feet? 10 feet, perfect.

Oh wait, you have a feeling that's 20 feet? Well, I can't go that high. I need to make sure I get this microphone down, so I need to hang it. Now you're talking about aesthetics, right? Because, well, I don't wanna see your microphone hanging down. Something has to give somewhere, right? To really have a quality experience. Because if I have the mic too high, can't really capture like I need to. Um, again.

Physics, the closer you are to the microphone, the closer, the closer the source being the human is to the microphone. The more, uh, the higher quality audio you're gonna have in almost every single case known to man. But there's cool microphones out here that, you know, they can do all kinds of things and arrays and beam forming and whatever term they put on them now, great. But there's still limits to it, right?

So you can't just put them in any environment and think, you know, if I hang a microphone that's 15 feet. In the air, and I have it competing with hvac. And HVAC is right beside the microphone. Or if I have, say, an older projector, it's got a fan and a lamp, it's making all this noise. If I put that right beside the microphone, okay, and now I'm injecting noise directly into the microphone. And again, that's just understanding what's happening in the room.

So is it like, okay, I need to like spray foam the ceiling. I need to put these little foam blocks in the corners. I need to get a rug. Like, what do, how do you, what do, okay. All

Because they'll go in and say like, okay, well this is spec'd that it won't produce more than, you know, 35 decibels. Okay, we can work with this, or 30 decibels, we can work with this. So all of that, you know, if you're building new is what goes on behind the scenes to check all those things, to make sure that you're not injecting more source sources of noise. But then once you do have those glass walls. Okay. Is there a film we can put up?

Is there, you know, something we can hang on the walls to start covering, you know, a certain amount of square footage to reduce this overall reflectivity? I mean, that's, it's just math, it's just equations to figure that out. And you, nowadays they have really artistic, beautiful looking, you know, acoustic panels. Um, you start dropping those in, try to put down carpet and do all these things, and that brings down your reflectivity of the surfaces.

Now you start to get into the realm of being usable. Right? Now we can start applying some technology, but then it's, then you get into that, the area of, well, what's the correct technology to use? Right? And everyone says they have the correct technology. That's just what, that's just what it is. You're trying to sell it.

Um, you know, we always say we wanna wow and delight as much as we can. So we have to really think about, okay, what's the right microphone? Not just what is the right microphone? Where does it need to be? And how do we blend the aesthetics? Because we want you to have a beautiful room. Everyone wants a beautiful room, but we have to make sure it can work for your use case or what's the point. Or you also get a lot of calls, right?

If you have, unfortunately, you know, a lot of AV calls get routed to it depending on your environment. But what are you gonna do? Oh, they're saying online that it sounds terrible. You're not going to fix that because you went wrong early because you have, you don't have the right microphone in the right space. Or we have, you know, a EC, which when I came from. Live space into the integration space. There wasn't a lot of a EC in live.

It's nothing thing you do, you do a mix minus you're good to go, come to integration, auto, uh, echo cancellation and all this other stuff. Um, but you have to think about that because otherwise it's, you know, getting the loop of the audio going back into the call because now it's too loud and the speaker, the microphone's picking it up, it's being looped back. Everything sounds echoey. Or if I am on one side of it, I'm saying, oh, I'm hearing myself back.

You know, all these things start happening now. Sometimes it's a case of. Hey, turn your speakers down, turn your own speakers down. But you know, if the room's not set up correctly and you know you didn't design it correctly, you start getting more of that. 'cause you have so much energy going into the room. The microphone's picking it back up. But again, that's where AC comes in. You start canceling some of that stuff out.

on Zoom or Google Meet and the audio is so bad I can't hear anything. So they call me, they put their phone in the middle of the table and then so we have a phone, I'm watching the video feed on one end and I'm, there's a phone that I'm talking to on the other and that is so common. I've done that probably a hundred times 'cause you can't hear people. And yeah,

Uh, you, you'd hope so, but if they didn't bring 'em to the table to understand the workflow and what's actually happening, they're just, sometimes they're copying like, Hey, we did building a, we're setting up a new building. We're just gonna copy building a well. Do you have the same users? Do you have the same workflow? Do you have the same needs?

You know, it's technology changes, you know, every, every week we're getting some brochure about some new DO ad that does everything you need to do. Um, but it just kinda gets lost in transition and then. There's actually more capital lost in more areas than what people think about.

So yes, you've invested all this, you know, in these buildings and you know, we, we see, when we see whole buildings going up, you're talking about potentially millions of dollars in audio visual technology going into the totality of a building.

Okay. Well now that employee is spending how many hours every single week fighting a room, trying to make it, just do what it's supposed to do. Okay. Well also go to the user experience side, even if the room in theory is working. To your point about the, the not great audio on the call. Well then how many people get tired of that? And they say, every time I have to use this room, the audio is just terrible. I use my phone anyway.

But now you've lost trust of I don't trust the system, or I'm trying to make adjustments, or I'm not using it the way it was meant to be used, and I just, I don't know what to do.

And that those little grates over time, they're very, very slight, but they add up and it makes either the relationship tense or what you're saying that like. People just don't wanna use the room. And so then you, you just have these like breakdowns of these tiny little things that I, I know everybody listening knows exactly what I'm talking about. But that, that kind of thing, I, I started to really pay attention to that.

And I've actually been seeing people more in person because of those little breakdowns or they, they're, they're, they're like friction in a relationship and it's starting to drive me crazy. 'cause I, I, 'cause I really value that. Yeah. Yeah. Exactly. It's

It's like, yeah, you can't just run a teams meeting off 2.5 megs of bandwidth. Not gonna work out very well for you. The more screens you have, if I have, you know, three displays and I'm sharing and I'm doing all this stuff. You probably need somewhere between five to 10 bags of bandwidth, which seems simple. Okay, well what else is, how much bandwidth do you really have? How many rooms are we talking about? How much bandwidth are you, you know, eating through at one time?

If you have 10 meetings happening across 10 different rooms, did you calculate all that?

Sure, maybe you do have 50 megs down, but if your upload is, you know, one and a half, uh, that's a nightmare.

Cable, the, the top of the line cable, and it was like 60 or $70, and it's like a little two foot cable. But prior to talking to you, I would've never done that because I'd be like, it's a cable. It's just a cable. I get one on Amazon for 10 bucks. But you have taught me it matters. And because I need the video, I need the ethernet, I need the, you know, I need everything to, to come into my computer. So

I'm gonna hook up a camera, I'm gonna hook up a microphone, maybe I'm hooking up a few other devices. All of those devices have bandwidth and they start to eat through that bandwidth. And there's just overhead calculations. You have to think about, well if all that's coming into that one port, that one USBC port, what was it rated for? And what kind of USBC port is it?

So that's, and again, that applies, you know, we talk about the personal computer side, but that applies through all the technology we deal with when we're installing things.

Uh, things that you've learned over the years regarding the math and the physics of it.

No one, you know, people don't have unlimited funds. Very, very true. Understand what, what are your needs? What are your wants? What are your have to haves? What are the, I can, I need it now and I'll add on later, and come up with a solid plan with a partner to get you, you know, a, a roadmap to where you want to go, how you're gonna get there. So you can manage that.

Because if you're in a race to the bottom, you're gonna pay twice probably in the life cycle of the time that where had you spent a little more, um, or, or went with something more reputable. You would've spent it one time and it'll get you through five to seven years. Whereas, oh wait, I'm gonna get the, you know, lowest cost item I can find. Well now you've replaced it, you know, two to three times in that five to seven year period.

And not to put on my, you know, environmental hat, but what are you really doing unless you make sure you cy it every time, you know, that's also contributing to waste. You know, I see people with displays that say, oh, I don't want a commercial display. Okay, I can go to, I can go to Best Buy and buy, you know, two or three displays for the cost of that one commercial display.

Or someone once told me I can literally replace it twice and I still would've paid less said, but again, you're throwing, I know you're not recycling them, so you're just going to a dump or a landfill with two or three displays in the time that you literally could have had one display working the whole time. So there's all these other things to just think about. Just, you know, what's your impact on the world? What's your impact in your own room? Do you want something to just die randomly?

Do you wanna have a little bit more control of like, Hey, this should make it and no one's perfect, but it should make it five to seven years versus, and when it goes, it goes and we'll deal with it being down, and now we'll go change it up.

So I mentioned like the cable, you know, any of my computer stuff or my display, like I, I, I just am in this. Period of my life. I want the best of the best because I'm gonna be using it every day. It's gonna last for five or 10 years. You know, I'm not gonna have to like upgrade every two years or throw things out. So yeah, you, you're talking like this, this had a big impact on me, just even personally, just the things that I'm buying and paying attention to now.

'cause I just want things that work and I know if I buy the very high end thing from the very reputable manufacturer, I'm gonna get the thing that I just plug it in and it works and I don't have to download some kind of driver or whatever and figure it out. It works.

Uh, I know there's a lot that you and your team, uh, do to put these faces together and make 'em really simple and elegant, but, uh, there's a lot of complex stuff going on underneath that people need to know about.