has its challenges. The University of Rochester, for instance, offers an audio
and music engineering program which already had a couple of recording facilities
on campus. With a vision for the future of the sound industry, and under the
leadership of Grammy Award winning audio engineer Stephen Roessner, this
rapidly growing major of study at the university needed new space.
accommodate the growth and development of the program, the U of R planned to
install a new recording studio with larger live rooms, multiple mix rooms and a
large control room for instructional purposes.
building that was selected was Gavett Hall. The team of experts hired to carry
out the task were AVL Designs Inc., SWBR architects and Bergmann Engineers
working in conjunction with the U of R decision makers.
greatest challenge in utilizing Gavett Hall for the studio is that the location
put the live room directly above a computer lab in an existing building. Live
rooms can have sound pressure in the 104dB + range when used for live bands. It
was critical that these sessions could occur without the computer lab hearing it.
Designs Inc. was contracted for acoustical design as well as creating an
infrastructure for equipment to be added at a later date. Working with SWBR’s
architect and their structural engineer, we had to find a way to assess what
options we would have for controlling transfer between floors. A floating slab
system was designed but it was being installed upon a substrate that was not
the standard for this type of system.
custom software, an estimate of field STC (Sound Transmission Class) for this
assembly was derived. Walls were designed to isolate the live room from the
main control room as well as from hallways and adjacent mix suites. High STC
doors from industrial acoustics corporation were selected for all of these
spaces as well. Final field tests confirmed that the floor to floor isolation
was within two decibels of design standards, which with a custom assembly is
noise in the spaces needed to meet very low levels, in the RC 20 range. We also
had to make sure duct runs and conduit did not create sound breaks in the wall
construction which was designed to high STC levels. This required specialized mechanical design
and electrical. Our AV design team
worked with mechanical and electrical engineers from Bergmann Associates to
achieve the desired results.
The university has since outfitted the spaces with their own equipment and have installed wiring to the infrastructure that was designed in the project and the project went online very recently.
In the past, auditoriums were generally purpose-built.
Opera houses were designed for opera. Orchestras often share the opera house by
adding a stage shell that would aid the orchestra acoustically.
Lecture halls were designed for speech. Movie
theaters were designed for sound reinforced by audio from loudspeakers.
Churches were designed for various styles of music and use. Some spaces were built around the required characteristics of a large pipe organ. As liturgical spaces are being repurposed for contemporary music and changing congregations, the results are often not very good.
auditoriums were never really multipurpose.
They were a middle of the road compromise.
When preparing to design a space from an
acoustical point of view, the first question that has to be answered is:
What type of
performances and uses should it accommodate?
Can I target a
style or do I need variable acoustics?
Unaided speech requires a quiet room, lower reverberation time and strong early reflections.
Orchestral requires a longer reverb time, extended bass response,
and a diffuse room response.
Contemporary music driven by sound
reinforcement requires a completely different room character. In order to allow
the sound system to control the experience, the room has to be subdued.
Live music can be
disappointing in the wrong environment. I remember once I was working with a
jazz artist and the auditorium we were booked in was entirely covered in thick fiberglass
wall panels. It was dead as a doornail acoustically.
Even when using
reverb effects, the room still sounded wrong. The reverb was coming from the PA
and the stage monitors, not the room. The side and rear walls were absorbing everything, not adding
anything to the sound. Not a great experience.
Overly Live Room
I also remember
hearing a favorite artist (Jazz/Bluegrass) in an opera hall. The room was so
live it was totally muddled. The sound system could not correct for the overly
How About a Variable Room?
If you build a
room with no acoustic variability, as and audience member or performer you are
stuck with what you have.
Variability to some degree can be accomplished with wall covering drop
curtains, rotating walls with various materials, and other options. Physical
options can be costly and they can take significant manpower to change for each
Most people are familiar with movie theater
surround sound. THX, Dolby, Dolby Atmos etc…. These systems create spatial
locations for sound sources using a multitude of speakers, each receiving
specific information to simulate where the sound would be coming from, or to
extend the “feel” of an environment.
While these systems are great for movies,
they aren’t deigned to work with a live musical
Fortunately recent advances in technology
have made it possible to go beyond surround sound into fully simulated live acoustic
environments. Imagine you are performing in a relatively plain room with a medium
reverberation time and not a lot of lateral energy. Walking the seating area,
you find that there are dead spots and changes in frequency balance. Your
ensemble sounds a bit thin and lifeless.
Like A Concert Hall
What you want for
your ensemble is a much larger room with elegantly tailored wood and brick surfaces,
diffusive in nature like a concert hall. Features like these are what makes concert
halls concert halls.
Imagine, now, an
electronic acoustic system that can create the sound of the room that you
are not in.
Is How Electronic Enhancement Works:
A series of prearranged microphones
pick up the natural sound of the ensemble, organ etc… from a suitable distance
so the sound is well mixed. This sound is then processed by a complex computer
algorithm that simulates how the sound would behave if it was occurring in a
simulated room. This sound is then precisely distributed and tuned to small
loudspeakers located to simulate the room you want to mimic.
Room tunings and character can be changed
at will. To the audience, it is entirely natural. It just sounds as if they are in a different
When the orchestra takes the stage, the
room gets larger and has added bass extension. The choral group gets a longer
reverb time with added midrange clarity.
For speech, the system switches to a voice lift mode and can improve intelligibility.
All of this is controlled by simple presets: Choral, Organ, Speech etc…
In order for electronic acoustics to work, the ROOM itself needs to be designed carefully from an ACOUSTIC standpoint, but in a different fashion.
Discrete echo has to be controlled. The enhancement system works with the room acoustics, but cannot cancel out physical acoustic defects.
of electronic acoustics requires coordination of the system elements with
lighting, ceilings, walls, HVAC, plumbing and other elements throughout the
design process. HVAC noise has to be very carefully controlled. Led lighting (much of which is now fan
cooled) has to be chosen and placed very carefully relative to microphone
acoustic conditions have to be designed to work with the system. This is not a
sound system, it is an acoustic system and placement of all elements are
critical relative to the room in which it is employed.
The results are well worth the effort. Performances are enhanced and audiences experience an enveloping detailed sound quality in auditoriums that were previously not.
AVL Designs Inc. recently completed a multi-faceted project at the State University of New York at Cobleskill.
consisted of a renovation of a lecture hall and a gymnasium field house. The
lecture hall space is now being used for more multipurpose events including
music, standup comedy, small theater presentations and video conferencing.
AVL Designs Inc. was
contracted by the architect to provide acoustic design, audio system design,
stage rigging, curtains, lighting and controls as well as video presentation
capabilities for their new lecture hall.
Before and after
photos show you the extent of the renovation, which was substantial. In essence, it was a “full gut” of the space.
house had two issues. One was extremely live acoustics making the room
unsuitable for many uses. Graduation and other events are performed in the
gymnasium and the sound quality was quite poor. The primary reasons for this
were twofold. One contributing factor was the acoustical condition of the room
and the other was the sound system itself.
The old system suffered
from poor intelligibility due to comb filtering. This was a result of a poor
design not poor devices. The new design includes Danley loud speakers which are
used for both bleachers and general court area audio. A fully distributed
system over the court is used for events such as graduation. Acoustical
treatment has been added throughout the gymnasium to reduce reverberation time
and to minimize first reflection energy from the sound system.
Both spaces were ready for use early this year and have been well received by the clients and their guests.
So, today we
were at a school that wanted a review of all their technical systems: stage
rigging, lighting, audio, video, curtains – everything.
As usual, the first thing that we found was unsafe stage rigging as well as unsafe stage practices such as building sets, suspending sets, etc. [Which is the subject of another little article: Sound in Schools Part 2]
The next discovery was lack of skills in knowing how to do lighting.
But the number one thing that came up, and it almost always does, is bad audio. Years ago someone wrote a book with the title “If Bad Sound Were Fatal, Audio Would Be The Leading Cause Of Death” [authors Don & Carolyn Davis] Yes, bad sound is a universal problem and, truly, the number one complaint from schools for their theater productions, as well as for just day-to-day meetings, lectures, etc. No one can seem to get audio to work. So, why is that?
Audio is not a Technical Skill
We were trying to explain to them why it is so difficult to get audio to work. And the first misconception that they had, as well as everyone else seems to have, is that audio is a technical skill. Audio is not a technical skill. Audio is a musical skill and, unless you have musical capabilities, you are never going to successfully do audio.
What do we
mean by “musical capabilities?” It means
that running audio for any kind of function is similar to learning how to play
a musical instrument. On an instrument if you play something in the wrong key
everybody knows. It is immediately apparent. They don’t look at you and go “gee, I wonder what is going on with that
instrument?” They just go “He’s
wrong. Let’s fire that guy.”
In audio, when
people get bad results whether its poor tone quality, muddy sound, feedback,
screeching – take your pick of aberrations that people get – it is all bad sound. When people look at how
to get this to stop, they think somehow that there is a magic fix to it.
Usually, they think it means buying new gear. Wrong.
that in all circumstances getting new gear will fix all audio regardless of who
is using a mic, how they are using a mic, what their voice sounds like, what
else is going on in the room, etc. That simply is not the case.
Another thing we hear a lot is directors telling their sound people to “get it set” and just leave it alone. Sure, if everything else doesn’t change at all ever. That scenario hardly ever happens.
first misconception is that the fix is a technical skill. It is NOT. It is a
musical skill! So that means the person doing audio should be able to play an
instrument. They need to be constantly staying top of the changes happening on
the source end, level, EQ, etc….on the fly.
has to be able to identify frequencies by octave band, at minimum. Third octave
band would be even better so that when they hear something they will recognize
“ oh, that is this frequency that is out of control. I need to fix that.”
So, that is the first set of skills. Develop self-ear-training. Ear
training is best learned from a musical perspective. You can teach it to a
technical person who is non-musical but it is a lot more difficult.
So you get this person, now, and you get him/her to the point where they actually have an idea of what certain frequencies sound like. That way when someone is performing and the sound person hears something they don’t like, they can say “oh, that is 250hz, if I can take some of that out they will stop sounding so “chesty” and the audio quality will be better.” Or “that squeal I am hearing is 8khz. I can pull the filter out and get rid of the feedback problem.” So they’ve got that skill, that’s great. You are on your way.
So, you have one mic sounding good. Now let’s start working with multiple microphones, multiple instruments. The nitty gritty of bad audio, if we were to put it in a nutshell, is the notion that if you get each channel sounding good by itself and then turn it all up, it will all sound great together. Based on that premise, if you want somebody to sound more in front of someone else, you just turn them up, right? Not exactly. Why not? Because that is not how the human ear operates.
Your ear can only discriminate a certain
number of things at any given time. Try this for an example: play a track of a bass player that sounds
good, full and crisp. Now turn on a fan in the room. Bass definition drops off
and, oddly enough, it sounds like there is no bottom-end. If, instead of a fan the
sound interference was cymbals, it would be even worse. Multiple “anythings”
have similar issues. Sounds mask each other. As the engineer, you have to
decide how to deal with that and make music out of it.
let’s just take a simple task: two vocalists as opposed to just one.
Put two people up there and let’s say they
have kind of similar voices and you have a hard time figuring out who’s who. When
you listened to each voice individually they sounded pretty good – and then
when you put them together it is just kind of two-dimensional.
You can’t really tell who’s who when they are
singing at the same time. Now, if they are in a duet or singing parts and
they are breaking apart, obviously that changes. But when they are singing
together, you’re not really hearing the voices independently.
One of the things people will do, if they are
mixing on a sound system that is stereo, is to pan one person to left and the
other person to right. And then, if you are sitting in the middle of the room,
that really separates them.
In live sound, however, if you are sitting on
the right or the left side of the room you won’t hear the other person very
well at all. So that approach is not a viable fix unless your sound system is a type that hardly
any average school has, where the left and right systems completely overlap
the entire room and provide true stereo in all seats. [We can talk
about why that is complicated to do in a different segment at some point.]
Most live sound is dual mono by default.Separation in the mix is done by other means.
So, let’s get back to the two microphones.
We really need to mix them in mono because we need to be sure everybody in
the room hears both singers, but we want them to sound distinct. So what should
we do? We will take some frequencies out of one mic that we leave in the
other mic to make them stand apart sonically.
Let’s say there is a male voice and a female
voice. In this instance, the goal is for the male voice to stand out in the low
frequency ranges but the female voice has some low frequency content. To make
that work, we will pull some low frequencies out of the female voice which will
separate the two.
Now, if we then listen to the female when
she is singing just her part, we have to bring those low frequencies back
in for a while to make her voice sound the way it should as a soloist. But when
they go back to singing in unison, in the duet sections, we will have to
pull her voice frequencies out to get the whole thing to work from that
So, it’s a constant movement, like playing an instrument.
You are not leaving things alone. The keyboard player doesn’t just play an F chord and that’s it. When they’ve got to play a B flat cord, they change to B flat. Channel equalization has to change in various songs and parts of songs. In essence, you are part of the band.
We get asked quite often about how to achieve speech privacy in office areas, doctors offices etc. It is actually a fairly complex question but here are some basic points to consider:
Speech privacy is a function of many factors. The first and most critical is “how loud is the source?” A loud speech source is more difficult to control than a quiet one. People can talk more loudly than you might expect especially on cell phones.
The next critical factor that comes into play is how well isolated that source is from the area you don’t want to receive the speech in.
In the case of enclosed office spaces, the construction of the space itself is the first line of defense for privacy. If doors, walls, and ceilings are not designed properly speech will transfer into adjacent spaces. These adjacent spaces we call “receiving areas.”
If you don’t want speech to be understood in the receiving area, there are other factors in play.
The first is how much sound actually got there, which is a direct function of the quality of the partitions that separate the space.
The second is how much background noise there is in the receiving area. If the receiving area is very quiet, you hear better. It is kind of common sense but it has become a problem. Old desktop computer fans made enough noise to help with privacy. Quiet computers, lack of background music (no one can agree what to listen to), better windows ( high R value equals less outside noise ) and quiet HVAC are actually problems for speech privacy.
If your receiving room is quiet, it is critical that the walls, doors and other construction are built to a higher level to prevent sound transfer.
Some of the things that can degrade the quality or an office are gaps under and around doors, HVAC shared duct paths, back-to-back electrical outlets, and lack of acoustical detailing in wall construction. Some aspects of wall construction are not obvious. The simplest is the insulation in the wall cavity. In the absence of batt insulation, a wall cavity becomes resonant and more sound transfers through.
The next issue is wall construction. Is it built on 16 inch centers? Is it built on 24 inch centers? Was the gypsum caulked when it was attached to the studs and floor plates? Are the studs wood or metal? These are all factors that play into the quality of the construction.
Doors need to have gasketing. Acoustical gaskets are similar to fire gasketing. It doesn’t need to be fireproof for the sake of a fire rating but if smoke can penetrate around a door, so can sound. The door itself is important, as well. A solid wood door is not a good selection because wood transfers sound well. Preferably, you want a metal door with an acoustical inner core that separates sound from the inside to the outside.
The types of seals that are used around the door affect not only the quality of sealing but also the longevity of the solution. Compression seals tend to only work for a short period of time before developing a memory and start leaking. Magnetically sealed doors, which are considerably more expensive doors to buy, are similar to your refrigerator. They reach out and grab the adjacent surface, creating an airtight seal, as does a refrigerator door. If you use compression seals on a refrigerator, it would tend to leak thermally, which is the same as leaking acoustically.
What if you can’t isolate the receiving room well enough due to factors you can’t control, such as walls that only go up to the ceiling with a big gap above where you can literally see above the ceilings of all the adjacent spaces ? Then you need to look at how to get adequate noise on the receiving side.
It is important that every area considered a “receiving area” is evenly blanketed in some sort of background noise. Background music is one way that used to be done. HVAC in some cases does the job as long as the fans are always on.
Another way is noise masking using shaped pink noise. This type of system is often used in open office plans to achieve a level of privacy. (It works far better if the source rooms are still separate spaces and receiving rooms around them have the noise masking.)
Basically, a noise masking system is a series of small loud speakers placed either in the ceilings or above the ceilings that generate a soft background noise similar to the sound of air conditioning. If done properly it will create a more private environment.