Acoustic Engineering Pros

A brief history of Carnegie Hall and its lucky story of becoming one of the best concert halls in the world! Definitely on the "places to visit" bucket list.

In your opinion, what’s the biggest difference between being a Transducer Engineer and a Telecom Engineer?

 – Larger Transducers are quantified using free field microphones, infinite baffles and Thiele Small Parameters.  Transducer Engineering is mostly about High Fidelity.   Telecom Engineering involves using Type 1 Artificial Ears and Head and Torso Simulators (HATS).  Telecom Engineering borrows most of the parameters from Transducer Engineering.  From there the objective in Telecom is maximizing double talk (full duplicity) and minimizing echo.  Telecom is all about voice. 

How do the projects that you work on differ?  

– Objective projects are much easier to quantify (using data), where Subjective projects involve opinions of others  (opinions are like assholes – everybody’s got one).

2.     What have you learned on the job rather than in school?  

– My education/diploma provided a foot into the door of my career and a solid foundation in math, everything else I learned on the job – there is no substitute for experience.

3.    What would you say would be your favorite project that you’ve worked on thus far? –

designing compression drivers at Peavey Electronics – this was my first job out of college and still, to this date, it’s involved my favorite projects.  Peavey Electronics is Pro Audio.  Pro Audio emphasizes reliability and objective data.

4. What kind of articles do you read/ look for in your free time? Are they related to work or completely irrelevant?   

– Articles from trade magazines:

Voice Coil, Sound and Communications, Sound and Video Contractor.  I also like to follow Online Audio Message Boards.

Check out this article we found from BBC News Magazine! These unusually sounding places across the UK may not be the most beautiful, but they sure do have some crazy sound effects!

Look at more interesting articles from BBC News magazine here: http://bbc.in/ZHRyIt

St Paul's Cathedral Whispering Gallery, London

The Whispering Gallery at St Paul's Cathedral in London is one of the few tourist sites known for its acoustics.

Thanks to a quirk in the building, designed by Sir Christopher Wren, a whisper can travel around a wall.

Stand on one side of the dome, with a friend 110ft (33m) away on the other, and whisper into the wall. The sound will skim around, hugging the wall, and be clearly heard by your friend.

Nobel-prize winning physicist CV Raman described what he called "mocking whispers" in the gallery.

"In response to ordinary conversation, strange weird sounds and mocking whispers emanate from the wall around. Loud laughter is answered by a score of friends safely ensconced behind the plaster."

The gallery in St Paul's is particularly adept at transporting whispers.

The sound is trapped against the inside of the curved dome wall, which is why it sounds surprisingly loud at the other side and appears to emerge from the wall.

This strange feature has been attributed to the slight curve of the walls. By tilting the walls inwards at the top, less sound goes upwards and gets lost to the top of the dome.

But like most whispering galleries, this magical property is an accidental by-product of the architectural design.

Wormit water reservoir, Dundee

The old water reservoir in Wormit near Dundee lies disused and hidden from view under someone's back garden.

It was built in 1923 in anticipation of the population of Wormit growing, but war intervened and the town never grew to be very big. Eventually, the cost of maintaining the oversized reservoir led to it being decommissioned.

It has few visual charms, it is just a vast concrete box about 200ft (60m) long, 100ft (30m) wide and 16ft (5m) high. It has a forest of concrete pillars regularly spaced about 23ft (7m) apart and holding up the concrete ceiling.

But as you talk the acoustic immediately reveals itself. A rumble builds up and hangs around like a smog. There are balloon popping sounds like a gun being fired, with a boom that reverberates around for ages.

The time it takes sound to die away is an important measure of room acoustic quality. In a classroom it is relatively short, so a teacher's words do not overlap and make speech unintelligible. Concert halls for an orchestra are designed with a longer sound decay, because the reverberation plays an important role in enhancing the music.

The sound takes ages to die away in Wormit. In most rooms the sound dies away because every time it reflects from a wall a little bit of energy is lost. In Wormit the room is very large so the time between reflections is very long.

Also the concrete walls are almost impervious to sound and so not much energy is lost each time the sound bounces off the walls. This is why it takes some time to die away. It is like a huge cathedral, with the great advantage that you do not have to wait for an evangelical service to whoop and clap.

Greenwich foot tunnel in London

This foot tunnel under the Thames might not be much to look at, but when the sound artist Peter Cusack asked people about their favourite sounds of London it was a popular answer because of the way it distorts voices.

Sound waves bounce back and forth across the width of the 1,215ft (370m) tunnel, distorting voices using the same physics which make some people think they can sing well in a shower stall.

You can also really let rip and hear the sound go up and down the length of the tunnel.

The recording of a skateboarder passing the microphone - listen to the audio clip on the right - sounds like a freight train because of the reflections from the tunnel walls.

When the skateboard crashed to the floor there was a reverberating echo as it hit the floor. The hard tiled walls mean the crash rattles around the tunnel for ages before dying away.

With nowhere else for the sound to go, the echo is impressively loud, travelling hundreds of metres to the end wall before returning.

Bitterns at Ham Wall, near Glastonbury

Ham Wall wetland reserve near Glastonbury in south-west England is home to arguably the weirdest sounding bird in the UK.

Bitterns are reclusive wading birds, a type of heron which makes the most extraordinary bass sounds that can carry for many kilometres over the reed beds they live in.

Their call is often likened to a distant fog horn. It's no surprise as it is immensely powerful. At 101 decibels at 1m, it has a similar volume to a trumpet. And at about 155 hertz, a typical frequency produced by a tuba.

The booms sound like someone blowing across a large beer bottle in the pub. Exactly what the bittern is doing to make the sound is unknown, because it is a rare, secretive and well camouflaged animal.

Rare video footage has shown the bittern's throat swelling up and the body convulsing as the air is gulped in.

As the males call before mating, it is assumed the females use the loudness of the boom to assess the fitness of the competing males.

The strange sound could also be a form of defence, with the males also booming during nesting, suggesting it is also used to guard feeding territories.

Anechoic chambers around the UK

There is an anechoic chamber at the University of Salford and it is the closest you can get to hearing absolute silence.

It is so quiet, in fact, that you can hear the sounds your body makes, like the blood circulating in your head or a high-pitched hiss, which is thought to be caused by spontaneous activity in the auditory nerve fibres within your brain.

The chambers come close to absolute silence

The rooms are used for carrying out acoustic tests such as measuring the performance of ear plugs, loudspeakers and microphones.

They are made so quiet by having multiple walls to stop noise getting in from outside. Like a modern concert hall, the Salford chamber is mounted on springs to prevent vibration entering the inner sanctum.

If you talk in the room your voice sounds odd, and very muffled, like listening in an aircraft when your ears need to pop. The walls, floor and ceiling are covered in vast wedges of grey foam which absorb the sound reflections you would otherwise hear from the chamber's surfaces.

How cool are these anechoic chambers? The one in this video is large enough to fit a small orchestra! Have you ever been inside one of these crazy chambers?

Research suggests that acoustics were just as important to prehistoric people as it is to us today! Read this article to find out more about how the concentration of artwork in ancient caves correlated with the greatest resonance... Crazy, right?!

We had the pleasure of speaking with David Burke of Grain Audio. Having a love for music, he built speaker boxes for his car at the age of 15, and sat and listened to music while parked in the driveway because he didn’t have his license yet-- A commitment to acoustics before he even knew it. He got his start as a Prototype Engineer and found his passion within the acoustics realm. During his time at Altec, he worked on, and patented the InMotion docking station for iPod’s and similar devices.  From there, he ventured away from Altec, and along with a few members of different specialties, they created Grain Audio. Currently, they are working on meeting a quickly approaching deadline for the launch of their blue tooth and in ear headphones. Those are just two of their products—the list encompasses passive audio bookshelf speakers and On-Ear headphones, too. Grain Audio sets themselves apart from the rest with their impeccable quality of sound and attention to detail. They use real wood to ensure that the quality is at its absolute best—something to be able to play music, and play it loud. In doing so, they have created a more challenging process for development; however, they would rather the challenge than to sacrifice the sound. Ultimately, everyone at Grain Audio cares about every single aspect of each product they create.

We'd like to thank David for spending some time with us. Check out their youtube channel for more info about who they are, what they do, and why they do it! 

We reached out to John Stojevich of Dynamic Show Productions and asked him to do a short piece for us here at Acoustic Engineer Pro’s. John Stojevich has been a live audio engineer for the past 17 years working in a variety of differing applications. Over the years he has worked for many artists and performers, corporate clientele, theatrical performances, houses of worship, clubs/venues, and a variety of concerts and festivals.  Some of the artists he has worked for include: Martina McBride, Uncle Kracker, Tantric, Saving Abel, Mya, MN Orchestra, Delfeayo Marsalis and Romantica.  Some of the corporate clientele he has worked for include Target, Health Partners and Procter & Gamble.  His experiences in working with these and other artists range from operating as FOH technician, monitor technician, RF technician and system tech.  In March of 2012, John established Dynamic Show Productions, a full event production house, proving event production for corporate, concert and touring clientele.

  We are pleased to share his piece with our community:

  Acoustics…Good or Bad?

Authored by:

John Stojevich

CEO/Project Manager/Audio Engineer

Dynamic Show Productions

  Acoustics are defined as: “a science that deals with the production, control, transmission, reception and effects of sound.”  When stated like this, it makes acoustics sound very much like what a Public Address (PA) system is, except that acoustics can either be naturally or artificially created.  For example look at Red Rocks amphitheater in Colorado or The Gorge in Washington.  Both a PA system and acoustics direct an auditory signal at an intended listener.  Just as we judge a speaker to be deemed “good” or “bad”, can there be a decisive definition of what is considered to be “good” and “bad” acoustics?  Or can acoustics simply be looked at as enhancing or projecting sound and/or deadening or diffusing sound? 

I believe that there is not a definitive answer to establish a space as acoustically good or acoustically bad.  Saying that would be similar to stating that “rock music is the only good music and all other music is bad.”  What you perceive to be “bad” acoustics for your intended purpose in mixing a rock group may be considered “good” acoustics by an orchestra or choir.  As live audio engineers, we need to learn to fully understand what our purpose is in mixing live sound and how acoustics affect what we do and/or don’t do.

If we are challenged by a space, are acoustics really what is at fault?  I feel like there has been an on going battle between live audio engineers and acoustical engineers to blame each other for things not sounding correct in a live environment.  If the acoustics of a space are excited “incorrectly”, the PA is to blame; if a space does not work well with the PA, acoustics are to blame.  Understanding that in any given situation there is going to be challenges and using the thought of adding more acoustic treatment to the space is not always the answer, just as adding more PA to a space is not always the answer.  When understanding what the intention of the space is, there is a properly executed quantity and type of acoustic treatment and PA to make a space acoustically pleasing and sonically balanced.

I feel that acoustics get a bad reputation in that they are always looked at as the enemy of live audio engineers.  But, how can a naturally occurring element, which makes sound possible, be an enemy to live sound?  What acoustics mean to live sound is not how do we overcome them, but how does this affect what the PA is doing in this environment?  How can it be looked at to benefit the sound as opposed to being a detriment?  What I mean by this is how can you use the acoustics to benefit the tonal quality and/or sound pressure level of the space?  If the room has a great build up of low end, find a speaker that has a reduction in that area or EQ that out and allow the room to fill out the rest of the spectrum.  If the room is very reflective, focus your PA to its intended listener to reduce the amount of excitement that can occur.  Maybe it means that you design a more distributed system so you can turn down each speaker set and not push the primary PA. 

Acoustics offer many potential challenges to live audio engineers depending on what we are trying to accomplish.  One solution for these potential challenges is to utilize some degree of acoustic treatment in an attempt to eliminate or reduce these challenges.  Beyond taming certain excited frequencies, what is acoustic treatment meant to do or actually doing to the space?  Is acoustic treatment meant to allow the listener to hear things as they naturally occur?  If so, would the absence of acoustic treatment then make things sound unnatural?  Hearing sound as it naturally exists has become a dying concept in today’s society.  We, as consumers, have come to rely on speakers to “perfectly” reinforce what occurs “naturally” in music or speech.  Consider an electric guitar; when you listen to that guitar amplified through it’s associated guitar cabinet, is that what an electric guitar actually sounds like?  No.  The sound has been colored by the choice in pickups, cabling, amplifier, cabinet and speakers.  So, if the intent of your mix is to reproduce what occurs naturally, the sound is already no longer “natural” before it even reaches the microphone, let alone how it sounds in the room.  So much music today is created on electrical instruments, without a speaker the sound does not even exist!  So, how can we judge a sound in an acoustic environment when that sound does not even exist?

So what is it then that we want to hear?  Is it sound as it naturally happens or is it the affected sound happening in nature?  Don’t imperfect acoustics actually provide us with a more “natural” sound anyways?  The standard stereo PA configuration already has a flaw in how it represents sound.  How is reproducing sound in defined sources considered to be “natural”?  Nowhere in nature does one sound emanate from multiple sources simultaneously; and conversely, nowhere in nature do multiple sounds emanate from one source simultaneously.  If we listen to a drum set being played acoustically we hear the direct sound of the drums, the reflections from the ceiling, walls, floor and all associated delays that end up making not only the image but the tonal spectrum of that drum set.  So if we try to mix a performance in the mono domain or even a stereo domain, we are automatically defining sound as not happening naturally, so why do acoustics matter anyway?  If “natural” or “organic” is what you are striving for, utilizing the full stereo spectrum a PA has in creating an image that is asymmetrical is actually a more “natural” way to hear the music.

"Vinyl is the real deal," White says. "I've always felt like, until you buy the vinyl record, you don't really own the album. And it's not just me or a little pet thing or some kind of retro romantic thing from the past. It is still alive. United Pressing Plant is two or three blocks away from here, and they're pressing up millions of copies of vinyl every year. And people are still buying them in droves." United has manufactured records for Motown and Music Row since it opened in 1962. These days, the old pressing machines are going full tilt. Third Man's director of production, Ben Blackwell, says he's back and forth to United on a daily basis as they collaborate on new color schemes for their limited-edition releases. United workers slice hockey-puck-shaped ingots of colored vinyl in two or three pieces and then reassemble them by hand. "And then that puck with the labels attached is fed into the actual record press, and approximately 20,000 pounds of steam pressure compresses that puck between two metal plates, which are the negative images of your actual record grooves, so when you have a record that has grooves, these pressing plates have ridges," Blackwell says. "It really is mystifying and captivating, too. It's almost like you feel something in the room while it's happening." Third Man is an auteur's project for sure: White produces all of the releases himself, including the latest music from 72-year-old rockabilly pioneer Wanda Jackson. White says he could tell he was swimming against the Nashville way of recording when he swooned over the first take of Jackson's song "Shakin' All Over." The veteran horn players wanted to fix mistakes. He was having none of it. "The more we try to work on this and perfect it, the worse it gets," he says. "And that's what happens nowadays with people working on computers. They can so easily fix things with their mouse and take out all the, 'Oh, somebody coughed in the background; we need to take that out' — or somebody hit a bad note. Those are all the best moments, and that's where music has taken a left turn and they need to get back on the road."

We recently had the opportunity to interview Kyle Banfield, an acoustic lab technician. His day to day includes characterizing prototype microphones that go in mobile devices—cell phones, tablets, etc. His passion for music drove him to work in recording studios where he had experiences with mixing music for a plethora of categories and private artists. He moved into the technical and the rest is history. He started his school career as a civil engineer, but changed his mind to move toward acoustic engineering. Unfortunately, his school didn’t have the said program, so he created one by developing a unique program that was Liberal Arts Engineering studies, an “oxymoron” as he explains it.

            Kyle is happy where he is, and is excited to go down the different avenues of acoustic engineering. His favorite part of the job is process of capturing sound and understanding the technical aspects of the manipulation. He loves the challenge of manipulating the sound. Being more on the technical side, he helps engineers with the design aspects. He explained that the microphones are getting smaller and smaller, so they are reaching some size restraints. He’d like to be able to have multiple uses in microphones, like capturing movement as well as sound. If this were to happen, he believes it would start in devices that are bigger rather than devices like a phone.

1). Red Rocks Amphitheater (Colorado, USA): This naturally formed venue is not only a wonder of nature, but is a perfect location for naturally amplifying sound. Due to it being outside, there are no walls or roof for sound to bounce off of and cause interference. Now thats a breath of fresh air.... and yes, pun intended.

    2). The Boston Symphony Hall (Massachusetts, USA): Built in the late 1890’s, the architectural team turned to a physicist whom modeled the building after the high and narrow European design over the fan-like design of many other American Symphony halls.

     3). Vienna Musikverein (Vienna, Austria): Built before anyone knew much about designing buildings around acoustics, this concert hall is known for its meticulous details being responsible for creating the rich sound and sonic perfection. Due to all the statues, decor, and high, thin design, the sound bounces off it all, making it warmer and richer. So was the architect brilliant or just lucky? At this point, who cares? It sounds freaking awesome.

  4). Walt Disney Concert Hall (California, USA): Although a very new building, it is designed to be one of the most acoustically accurate concert halls in the entire world. The building took 16 long years from start to finish, but hey, leave it to Disney, right?

  5). Slane Castle: The grounds of this castle are a natural amphitheater that can fit about 100,000 people! It’s in the middle of nowhere, so no other sounds will be interfering with the perfect harmony of the music.