Inspired Acoustics: How to Be Productive in Life and Work With Acoustics With Charles Salter

Alexander McCaig (00:10):

Hello everybody and welcome back to TARTLECAST. You're here with myself and Charles Salter, who is one of the foremost pioneers in audio engineering. He may tell me otherwise, but I got to say, if you want to understand sound and how sound affects our lives, he's the only person you should be speaking with. So Charles, thank you for joining us.

Charles Salter (00:37):

Nice to be here, Alexander.

Alexander McCaig (00:39):

Really appreciate that. And you'll know that I have farm animals behind me and you can hear that because I'm out in the country. And for a lot of people, background noise can become an annoyance or it can become something of beauty. So I'd like to understand, how did your career of understanding sound carry to where you are on now doing the analysis of sound and then sharing that analysis with businesses to improve environments? So can we start with the beginning for you?

Charles Salter (01:17):

Very good, I'd be glad to start. It started off when I got a degree in civil engineering, structural engineering and a minor in economics. I went to MIT and studied architecture, minoring in city planning, but also spent a year studying acoustics. Then I went into acoustical consulting about 53 years ago. After a little while, maybe a year, I decided I need another degree, so I went back to school at night and I got an MBA degree where I majored in finance. So I didn't quite know what I was doing, why I was doing it, it was just very instinctual, but it's worked very well. I went on to start my own firm. One of my first projects was a very large legal case in the state of Nevada. My father was an attorney for 55 years, so I had this affinity for helping people deal with the legal issues, which is what we did. And so my career evolved, I learned from all these experiences, put together economics, business, architecture, engineering, expert witness work to where I am today.

Alexander McCaig (02:54):

So you put together this work, expert witness testimony, how is it with sound that understanding in it, breaking it down can actually help things like a court case? How does the data from sound transition over to a judicial sentencing?

Charles Salter (03:16):

Well, the first case I was involved in really exemplifies exactly what you're asking about. The state of Nevada was building a new freeway near Carson City and Reno. And some of the property owners felt that the freeway noise would cause their property values to diminish and they sued the state of Nevada for millions of dollars. So the jury, it was a jury trial, and the jury heard about freeway noise, how awful freeway noise is, and what my job was is to educate the jury about noise. And so we did an acoustical analysis and explained to the jury. We did audio recordings, we showed the jury photographs and we had them understand the state of Nevada's side in the dispute and how engineering the freeway in the way we did would not increase the noise for the people living adjacent to the freeway. So that was our job and we were very effective in educating the jury to understand the aspects of a noise and noise impact.

Alexander McCaig (04:45):

What is it about the aspect of noise? How do I understand when noise becomes an annoyance? Is it a function of the wave? Is it the frequency? Is it the resonance? What is it you look for that would then determine that thing would be an annoyance or something that could even cause damage to human tissue over time?

Charles Salter (05:10):

There are two important aspects to noise in noise assessment and noise impact. There are the objective aspects of it. There are state and federal standards. There are standards for hearing damage risk, very objective. You either exceed those standards or you meet those standards and those are the agreed upon standards throughout the world or throughout the community. Objective. But then we have subjective standards. And there are some people that are very sensitive to noise and will complain about any noise not of their own making. So if you design a building, an office building or a residence, and let's say 10% of the people are complaining about noise, you know you've done a perfect job because that 10% of the people of a given population is very likely to never be satisfied.

Charles Salter (06:11):

What I'm saying to you is the research work that was done by one of my colleagues a number of years ago and that is really important to understand that if you've got one out of 100 or five out of 100 people complaining about noise, the acoustic environment is fine. You will never satisfy that group of people. Then there's 30% of the people who are not sensitive to noise and they could be in an acoustic environment that will annoy you and me and they would say, "Oh, the noise doesn't bother me." And so it's for this 60% of the people that would be considered normally sensible, that these acoustical standards have been developed for.

Alexander McCaig (07:01):

So did you help in defining those standards through your own practice, even in a subjective approach?

Charles Salter (07:08):

Well, I took the research that was developed by one of my colleagues, a fellow named Ted Schultz. This was work he did maybe 50 years ago and I have embraced that information and passed it on to people who ask the questions like you're asking, "Charlie, how do we know a noise is annoying?" And I break it down objective, subjective and you will find people who are going to be complaining. So there are many aspects to noise complaints that are fascinating to me from a legal sense. But then when I'm doing my acoustical design work, I bring this experience and insight into my design practice.

Charles Salter (08:00):

So I'm talking to a developer or an architect during the design phase and they're saying, "Oh, we can't afford good acoustics." And I say, "Well, I hear what you're saying. However, if you don't do it right the first time, you may not be able to rent your hotel rooms or rent this." And they say, "Oh, rent. Oh." And so you need to communicate in a way they'll understand. And because it's very easy during the design phase to say, "Oh, we can't afford this. We need to cut the budget." Not really understanding the ramifications of that.

Alexander McCaig (08:40):

So how do you design for good acoustics? Is it the shape of the room? Is it the materials that are used? What is it that enhances the acoustics altogether?

Charles Salter (08:52):

Well, there is room acoustics and with room acoustic sound of the room, the room shape, the materials and the requirement for the room. So let's take an office where you're doing video conferencing. There are objective acoustical standards for acoustically treating a room to meet the needs for video conferencing. Okay. That's room acoustics. Independent room acoustics, you have sound isolation. So you're sitting in a room, you're trying to have a conversation, how much noise is going to come from outside, inside or through the walls or through the four ceiling construction. Sound isolation. Independent of sound isolation, you have the ambient noise in the room, the air conditioning noise, or the steady state noise in the room. And so all three of those room design aspects need to be addressed and if you just handle one or two and you miss one of them, are you going to have problems?

Alexander McCaig (10:02):

So Charlie, can I call you that?

Charles Salter (10:07):

Absolutely.

Alexander McCaig (10:08):

Awesome. Thank you. Can something be too silent where it becomes uncomfortable? So you hit a threshold of people that complain, but what if you just make it too quiet?

Charles Salter (10:18):

I've had one room in my career that was judged to be too quiet and I'll describe that room to you. It was a meeting room for attorneys and the architect had a carpeted floor, an acoustic tile ceiling, and all four walls had padding on them. And the room was just too dead, it was uncomfortable.

Alexander McCaig (10:43):

So I know I had looked at some of histories before. There's a gentleman who made a soundproof room up in Massachusetts, and they say that if you spend a good body of time in there, it's so silent, you can begin to hear the blood flow through your body. So is that what's going on for the lawyers?

Charles Salter (11:02):

Yeah, it was just uncomfortable. It was unpleasant. It was like having conversation in a closet. So you want a certain room acoustics quality. You want the room to sound natural rather than too dead or too echoey.

Alexander McCaig (11:20):

So what defines natural? I have roosters going in the background. That's pretty natural for me, right?

Charles Salter (11:27):

Yeah. So that's a different aspect. We're talking about in a teleconferencing room, a room that you want to be comfortable in. You're able to hear clearly, you're able to hear yourself. It's just not dead when you speak. And so there are objective standards that have been developed over the years. Industry standards for room acoustics where a classroom or a teleconferencing room would sound natural or normal.

Alexander McCaig (12:02):

So for that level of normal, and we're talking about physical structures, do these still objective and subjective standard transition over to things like film or even analyzing data sets and finance?

Charles Salter (12:23):

I'm not sure I understand. Translate over to film.

Alexander McCaig (12:26):

Yeah. So in movies.

Charles Salter (12:29):

Yes.

Alexander McCaig (12:29):

If I have the design of sound coming around me, for instance, I have a rooster in the background. Is choosing objectively where that rooster might be a benefit or something that could be detrimental to a film, just like if I'm engineering a home structure, does that carry over the same way?

Charles Salter (12:51):

So you're talking about in film recording, post-production?

Alexander McCaig (12:56):

Correct.

Charles Salter (12:56):

For film. Yes. We've worked a number of those facilities and typically the organization knows exactly what they want. They say, "Go to studio A, we want to replicate studio A over here, but we want to it twice as large." And so you go over there and you do benchmarking and you know exactly what they want. And that's very straightforward. Now there are computer programs that can also predict what a room will sound like. And we avail ourselves of those tools. And it's the kind of thing where you can't afford to not do it right the first time. So you do the benchmarking, you do the oralization using computers and you work very hard to make sure that the audio engineers be very satisfied with their environment.

Alexander McCaig (13:58):

So is there a structure that works better? I know that sound doesn't like bouncing off four corners. Right? I know that being in spherical objects carry sound better. The earth is round. Yeah. It has a resonance to it. So have you found that structures are actually engineered improperly from the start, from just how humans build things out of efficiency and that makes it more difficult to engineer for sound?

Charles Salter (14:31):

That's an interesting question. As I'm hearing you articulate it very often, the architect has the shape of a space that they want. A seating area, a ceiling height, because with acoustical design, it's integrated into a building design. And so we got to be thinking about lighting, natural lighting, artificial lighting, ceiling height, aesthetics, and then you evaluate the room and you say, "Okay, here's how we make this room work for you acoustically." Then the architect pushes back and say, "Not really. Can't shape the room that way, what about this?" And you go back, forth, back and forth. And that's where communication comes in, accurate communication. Because if you say to somebody it's going to be too noisy or won't sound good, they have idea what you're talking about. So you need to find the right words. You need to demonstrate to the lay people that you're talking to about the problems.

Charles Salter (15:42):

And you just, as I say, make that effort to educate them. And what's interesting Alexander, when you work in these design projects is some architects work very hard to do it right. Then other architects are really lazy and they're fixated on their design and they really don't care about acoustics. So have these both type of architects and you just can't take no for an answer. You need to do your job in a professional manner, express your concern, that if they choose not to listen to you, what the ramifications will be an unhappy client.

Alexander McCaig (16:25):

And no pun intended with [inaudible 00:16:27]. So how do you define noise as beyond the objective part? If I go to look at data in general, or if I hear the news or I walk into a supermarket, there's a certain amount of noise going on, but the human mind knows what to ignore. Or sometimes somebody can create noise that creates a sense of focus. How do we know what to focus on? Is that built up through human preference over time? Or is it synthetically engineered to catch our attention? Or is it a combination of both?

Charles Salter (17:11):

I think it's a combination of both. And obviously it depends on your mood and what you're thinking about and what you care about and what annoys you. For example, in your home, okay? Let's say you're living in a multifamily development. You do not want to hear your neighbor, right? You don't want to your neighbor because you're at the mercy of your neighbor's noise. And if your neighbor is acting unreasonably, then you're very angry and you go talk to your neighbor and your neighbor is a narcissist and they never do anything wrong. And you're unreasonable, and all of a sudden you're very stressed. So every time you hear your neighbor's noise, right, you become agitated. Versus let's say you get along really well with your neighbor and you hear them, but you're friendly and they're really nice and okay, my neighbor's home. That's great. So there's so many different aspects to hearing noise and how it'll affect you.

Alexander McCaig (18:22):

So are there any things that people can do actively in their homes right now that would be beneficial to their environment and how noise carries through their environment? Is it within their power or does it require an engineer?

Charles Salter (18:40):

That's an interesting question within, obviously you'd have to talk specifically about what the issue is. So let's start with your home. There's nothing more important than getting a good night's sleep, right? In terms of your physiology or acoustics, there's not one thing you can name that's more important than being able to sleep and being disturbed, being awakened. Wouldn't you agree?

Alexander McCaig (19:10):

Yeah. Probably sleep, oxygen and water.

Charles Salter (19:14):

But in terms of acoustics. In terms of acoustics.

Alexander McCaig (19:15):

Yeah.

Charles Salter (19:18):

Okay.

Alexander McCaig (19:18):

Sleep, most definitely.

Charles Salter (19:20):

So you start off with your bedroom and you say, "Okay, when the truck goes past, it wakes me up and it's hurting my health. I'm being disturbed, what can I do?" Well, I have a limited budget, or I have an unlimited budget and you work at sleep disturbance and you have to be very specific about what the issues are in your home. And then you figure out whether it's something you can do or whether you need an engineer or whether you need to move.

Alexander McCaig (19:58):

So say for instance, I am getting disturbed. Is sound really the most important precursor to all sensory input before visual? And the reason I say that, I know we use a majority of our eyes, but sound ends up defining a lot of the choices we make, where we choose to live before we even see something. Something could look beautiful, but sound could absolutely destroy it. So is sound really the most important data point when it comes to how we choose to live or where we choose to do business or look at datasets or understands what people are saying? Is sound the defining factor?

Charles Salter (20:49):

You're asking a question that never been asked before. I haven't really thought about what's more important. I'm not that knowledgeable about sight versus sound, but what's interesting about sound is to look at it from evolutionary point of view. So think about our ancestors living out in the jungle, at the mercy of animals, at the mercy of enemies. And you had to hear what is going on. Very important. And so if you hear a lion roar, then you'd be scared. You'd move away. You'd figure out well what to do. And so hearing is a great protector for the human species and we can't block out sound. So you hear your baby crying, right? You viscerally respond to that stimuli because if we didn't, then our species would've died off long ago. And so that's an interesting way that I look at sound, the importance of sound. But then getting back to the subjective part of it. There's some people that don't react to sound in a reasonable way. Other people have no problem in adverse environments.

Alexander McCaig (22:19):

Well, it makes me wonder, should I be paying attention to this rooster in nature? Is this a threat? I can't see it, but I can hear it. When I consider these things is it because we've synthetically engineered our environment where a lot of people have stopped focusing on sound for survival, and it's really become more of a thing of defining economic value? Oh, I can rent this place. I know where to be. I want my privacy. I don't want to become annoyed because things aren't really a threat to my life. Do you think that has slowed evolution, human evolution, because a lot of people really don't focus on sound anymore?

Charles Salter (23:07):

What I see in my practice is there's more and more focus on sound because if you're in an adverse acoustic environment, let's say an open plan office, noisy, you have no privacy. You're being bombarded with speech or ventilation noise. It increases stress, okay. It can hurt your health, and so a larger corporations are working very hard to improve the acoustic environment for their health of their workers to reduce stress. And so the number one complaint about office environments is acoustics. I'm not sure if you're aware of that. Number one.

Alexander McCaig (23:58):

I had no idea. Is there number two?

Charles Salter (24:01):

Number one. So of all of the complaints that people could have in an office environment, the heat, the light, the glare. Number one complaint, acoustics. And what people complain about in their office environment is they have inadequate privacy. Number one, they can't carry on a private conversation, telephone or face to face. Number two, noise. Noise, results in stress. So the term that you might find interesting is biophilia. Are you familiar with that term?

Alexander McCaig (24:44):

Is that like a love for life?

Charles Salter (24:46):

Yes, it goes back to the natural environment. And so how do you create an acoustic environment that causes people to relax? So for example, research has determined that when you hear the noise of a distant waterfall, steady state noise of water, that is very relaxing. And particularly if you can see and hear the water, because from an evolutionary point of view, when our ancestors were near water is very important for survival. And so this research finding what is a natural way of reducing stress for people has just started recently because of complaints from people about acoustic environments.

Alexander McCaig (25:40):

Interesting. So the more people we have, crowding spaces, synthetically designed, we're going to look to nature to help redesign that sound environment. Decreasing stress, increasing productivity, people can maintain higher focus. For instance, I am outside, I have my bare feet in grass. I'm surrounded by nature. It has its own inputs, but I feel calm. And other people will be like, "Oh, the background noise." But a bird song, running water, those things are calming. They may not be at the forefront of your thought, but they carry through subconsciously and do relax the body. And so I can absolutely agree with what you're talking about. I don't know for the roosters case, but definitely for that, for the waterfall, at least.

Charles Salter (26:28):

Yeah. Let's take the rooster. If the rooster is far enough away and you hear it, it's fine. If the rooster is very close to you and therefore interfering with your ability to hear, then it's annoying.

Alexander McCaig (26:42):

No, you're absolutely right. It's at a distance, but the noise canceling headphones help. So speaking of that technology, do you know anything about noise canceling?

Charles Salter (26:53):

I know quite a bit about, yes.

Alexander McCaig (26:57):

So is it like a resonance that it's matching up? What is it where the headphone can cancel out sound that happens from the outside? How does that actually work?

Charles Salter (27:10):

Okay. The way it works is that there are microphones that pick out the ambient sound and creates a sound that is out of phase with the offending sound and it helps cancel it. Particularly if it's pure tone sound. And so 50 years ago, I went to an acoustical society meeting and Japanese acoustical engineers were canceling the sound of a transformer noise at somebody's house. And they showed how they did that with the antinode. So the technology has been around for long time and it works very in headphones.

Alexander McCaig (28:04):

Does that work for physical object? So say for instance, I'm in an area that's earthquake prone. Can I take the same aspects of sound and apply how we understand that research and data, and then transition that over to building structures that cancel out other types of waves? Does it work like that?

Charles Salter (28:31):

With respect to earthquakes, I'm not sure how that would work, but in terms of the sound, sound cancellation does not work in a room. It just works at one point like your eardrums.

Alexander McCaig (28:46):

Wait a minute, explain that.

Charles Salter (28:47):

Okay.

Alexander McCaig (28:48):

So the room can't do overall sound cancellation?

Charles Salter (28:51):

Correct.

Alexander McCaig (28:52):

But a point can.

Charles Salter (28:53):

Exactly.

Alexander McCaig (28:54):

Why is that?

Charles Salter (28:56):

Well, because you're beaming the antinode sound created artificially within the earphones at one point your eardrums. But if you say, well, I want to cancel sound at this point, this point, this point. The technology doesn't exist to be able to do that.

Alexander McCaig (29:19):

You'd have to have like this radial projection of the sound wave, right?

Charles Salter (29:25):

Correct.

Alexander McCaig (29:26):

I'd have to set up like a spear in the middle of a room to cancel that all noise.

Charles Salter (29:30):

Yeah. And so a lot of times people ask me, "Charlie, is there a machine that I can cancel sound of the room?" And I say, "The minute there's a machine like that, I'm out of business." You don't need me anymore. You just buy this machine.

Alexander McCaig (29:43):

I'm going to prevent it.

Charles Salter (29:46):

No, I'm just saying for my business, the technology doesn't exist and as a result, people need my help.

Alexander McCaig (29:55):

Wow. I think that is really fundamentally interesting. And I'm glad we could talk about this because sound doesn't get enough focus. And I think it had tapered off and bringing an awareness to one of the most evolutionary, I don't even how to say that word, important aspects of our senses. We need to be maintain that focus. And if we want to engineer a future that is more stress free, that is more natural, has a more biophilia and less roosters. Then we need to focus on sound, wouldn't you agree?

Charles Salter (30:38):

I agree. And I'm happy to see that a lot of the cities and the federal government has renewed the acoustical standards and the requirements for sound because of the complaints and the realization that it's something that in order to make cities livable you need to reduce the noise impact.

Alexander McCaig (31:03):

Yeah. Because populations are increasing and the amount of noise from cars and other technology would make it unlivable.

Charles Salter (31:12):

Yes.

Alexander McCaig (31:13):

So are you seeing anything really interesting for our future in terms of technology around sound that we should look out for?

Charles Salter (31:25):

Nothing specific with respect to technology, it's applying a lot of the technology that's been around for quite a while using computer analysis and using good design practice to achieve great environments. This weekend for example, I went to San Diego, they had the opening of the new outdoor amphitheater for the San Diego Philharmonic. And my understanding is that that facility, that outdoor entertainment facility is one of the best of its type in the world using new technology. So that's an example of an advancement. It's about a 100 million project. It seats about 10,000 people, for the Philharmonic, as well as pop, presentations, theater, et cetera, in an outdoor venue.

Alexander McCaig (32:30):

It's like a $1,000 a seat. That's a pretty expensive setup. But it's to make things sound beautiful and although we do have all these sounds around us, they're the things that help push us forward. And sound is just another one of those advancements. So Charlie, if somebody wanted to find out more about you, where would they go to do so?

Charles Salter (32:53):

We have a website and it's www.salter-inc.com. We're in San Francisco, we have offices in San Jose, Los Angeles, Seattle and Hawaii.

Alexander McCaig (33:14):

Oh, awesome. Well, listen. I appreciate you coming on here to talk about sound. Listening to me, listening to the animals, and I know that this will carry its weight in people's ears and help us turn the tide on engineering and human evolution. So Charlie, thank you very much for coming on.

Charles Salter (33:35):

My pleasure. Thank you.

Speaker 3 (33:44):

Thank you for listening to TARTLE Cast with your hosts, Alexander McCaig and Jason Rigby, where humanity steps into the future and source data defines the path. What's your data worth?