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Improving your room’s acoustic system.

When RPN magazine needed an article to teach readers how to improve their room acoustics, they turned to Acoustics First® to get the scoop.

 

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YOUR ROOM’S ACOUSTIC SYSTEM – and How to Improve It

Ever wonder why some rooms sound better than others? What components contribute to
perception of sound in a space? What knowledge do you need to solve the sound problems that
you have?

The System

When people read the heading “The System,” there will be a great number who assume I am
talking about the “sound system” in a room – the speakers, amplifiers, signal processors, and
other electronic components that generally produce sound in a space. This is only part of the
acoustic system that creates the soundscape we hear when we are exposed to sound in a space.

Yes, sound comes out of speakers, and they are important, but the source of sound isn’t what
gives us a perception of the space we are in – it’s the space itself!

The walls, ceiling, floors, seats, sculptures, drapes, artwork, construction, and even people in the
space are all contributing to how we perceive that sound source in any given acoustic
environment. I’m not saying that the speakers aren’t important – but they are just the source of
sound.

If you have a room with a 5-second reverb time, it doesn’t matter what type of speakers you
have, any sound they make is going to continue to be heard for five seconds – as is every sound
afterward.

What does this mean? Even if you have the best speakers in the world in that room, it will sound
terrible (unless you are listening to Gregorian Chants…then it will sound awesome.)

However, if someone is speaking at a normal rate of speed, it will be unintelligible after the first 2
or 3 words – as those words will continue to bounce around with the sound of the next 15
words…like listening to 15 people all saying different things at the same time.

Your room is an acoustic system – from the sound source, to the ears of the listeners – as well as
everything in, around, and even outside of that room.

The Acoustician

Have you ever watched an acoustical consultant begin the analysis of a new space? It’s
fascinating. You will undoubtedly see them walking around the room while making noises –
clapping their hands, snapping their fingers, whistling, even talking loudly, shouting, and singing.

It’s as if they are bats using different sounds to figure out the characteristics of the room they are
in. They are, in fact, analyzing the room’s acoustic system. Where does sound reflect? Are there
echoes or flutter? What is the character of the reverb? They look at the structure, materials,
corners, architectural elements, floors, carpets, walls, windows, doors, ceilings and more.

Note: They begin this analysis WITHOUT using the speakers.

Why? If the room is bad, your speakers will not fix it.

What are they doing? They are listening. That’s it. Nothing fancy here – just listening.
I will say that many acousticians have done this so many times, in so many different spaces, that
they have an idea of what the room is going to sound like, without even making a peep – just by
looking at it. What are they looking for? What are they listening to? What can you learn from this?

Time to Listen

Everyone has a room where they dislike the acoustics. Go in there. Clap your hands. What
happened? Clap again. Snap your fingers. Make some noise – but make sure to listen. Where is
the sound coming from? Turn around, clap again. Walk to another area…clap.

As you walk around, you will hear the sound change. Turn your head. Is the sound coming from
the corner, the ceiling, both? Angle your ears in between two corners. Maybe that’s where it’s
coming from. Is there a large open balcony or a curved wall? Ask yourself these questions as you
walk around and listen.

Are any of the surfaces hard? What about the floor? Is the sound lingering over your head up in
the ceiling? Is there a defined slap off the back wall when you clap your hands? Is there a ringing
noise? Does the echo wash over you and linger?
Sharpen your listening skills. Map the room with your ears.

What Are You Doing in the Room?

This is an important question. For most uses involving speaking and understanding speech, there
are some good general targets. For example, for most rooms over 100m3 (15’ cube), a 0.8 to 1.7
second reverb time is ideal for many different functions.

However, keep in mind, some spaces may have special reverb requirements. If you’re doing
Gregorian Chants, a three to five second reverb time is still great!

Now, How Do You Fix It?

Most rooms are going to benefit from reducing the acoustic energy in the space. Absorption is
the most direct and easy to understand method – add soft stuff.

This sounds overly simple, but the initial experiments on calculating absorption were done by
moving around seat cushions – simple, but effective.

Fabric-wrapped absorber panels are today’s high-tech equivalent to the seat cushions. Curtains,
blankets, carpets, and other soft materials will also help to reduce the acoustic energy of a space.

Treatments like diffusers help to reduce focused acoustic reflections by spreading the energy
around. When sound hits a surface that is not flat, it will cover the entire surface, bending
around the corners and curves, and then bounces off in different directions.

This reduces what we refer to as ‘specular’ reflections – or direct, mirror reflections – which are
responsible for slap echoes, ringing, and flutter.

However, some hard, reflective surfaces in the front of the room can be beneficial to help
reinforce acoustic sound sources, like speaking, singing, or acoustic instruments.

Treating corners with bass traps can help to reduce bass buildup, as well as corner reflections,
which can cause other clarity issues within the listening environment.

Don’t forget…look to the ceiling for rafters and other elements that cause sound to bounce
around and put some absorption up there.

 

 

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WKNC 88.1 completes renovation with Sonora® – and then does another!

Sonora® Panels complete the HD-2 studio renovation. (Photo- J. Gilbert)

Renovating a broadcast studio is a daunting task – technically, financially, and logistically.  Amidst the chaos, it is possible for certain things to fall through the cracks – even important things.  As the student run station at NC State University began their renovation, they were focused on doing it right, and not letting important elements go unaddressed.

When Jamie Lynn Gilbert, the Associate Director of Student Media and Adviser to WKNC 88.1, contacted Acoustics First they were finishing up an extensive renovation of the HD-2 studio and were looking for some Sonora® Acoustic Panels as the “final touch.”  The end result was the frosting on the cake of this renovation, and the impact, both acoustically and aesthetically, was quite evident – even to their consulting engineer on the project.

 

Sonora® panels in WKNC HD-2 studio – reverse angle  (Photo – J. Gilbert)

So evident, in fact, that just a month later, Jamie was back in contact with Acoustics First® to get nearly identical treatment for their production studio as they completed its renovation as well…

Nearly identical Sonora® Panel treatment for the production studio. (Photo – J.Gilbert)

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Sonora® Ceiling Baffle vs. Sonora® Ceiling Cloud

There are many situations in which it is valuable to use ceiling treatments to control sound in a space, and after ceiling tiles, two other popular options are either Sonora® ceiling clouds or Sonora® ceiling baffles. What is the difference between these two, and when is it desirable to use one over the other?

It may help if we first define the physical characteristics of the two treatments. The similarities are in materials, and the differences are in implementation. Both are fiberglass core substrates covered in an acoustically transparent fabric; however, a baffle is completely wrapped in the fabric, while the ceiling cloud is often left uncovered on the back – to assist with mounting.

The main difference between the Sonora® baffle and the Sonora® ceiling cloud is the hanging orientation. A baffle is hung from its edge in a vertical orientation, while the cloud is hung horizontally, often parallel to the ceiling. The major benefit of both of these products is that neither is directly mounted to the surface, allowing all of the surfaces of the absorptive material to be exposed to sound – this makes them extremely effective at mediating airborne sound.

If they are both so similar, why do some situations benefit from one over the other?

Due to the horizontal orientation of the cloud, they are great at removing hard reflections off of the ceiling – say over a mixing position, in a listening room, or between the ceiling and a large conference table. They can be used to make a false ceiling by hanging them below a high ceiling – creating some intimacy in the space, both aesthetically and acoustically. By leaving space between the clouds, sound can travel up and around them, losing energy as it travels up to the hard ceiling, bounces off, and passes back through the absorbent substrate. This makes them very effective at deadening the hard first reflections and helping to reduce reverb times by removing the energy early. They require some skill in hanging, as they have multiple mounting points on the rear, and can be difficult to level – but the aesthetics are worth the extra effort.

Sonora® Ceiling Clouds – Note the horizontal Orientation.

The ceiling baffles hang vertically, which generally changes their implementation. First, they require higher ceilings, but this also means that they are very effective in larger spaces, because they hang down lower. Also, hanging a large array of baffles is a quick and easy process, with many only having 2 mounting points. They are great for controlling reverb in large spaces where sound could be coming from many different locations in the room – like a gymnasium, multi-purpose space, or cafeteria. Due to their vertical orientation, it is not likely that objects (volleyballs, basketballs, kickballs, etc.) will get stuck on top of them, which is more plausible with the clouds. Sonora® Baffles lower the reverb time by addressing the sound pressures up in the ceiling area, and create labyrinth for sound to run through. A large grid of baffles will increase speech intelligibility substantially in larger spaces by trapping the sound that usually bounces around in the rafters – an ideal use for the humble baffle.

Sonora® Ceiling Baffles – Note the Vertical Orientation.

So, those are some of the similarities and differences between the Sonora® ceiling baffle and the Sonora® ceiling cloud, and while they are very similar in their construction, they do have different scenarios where their strengths shine.

If you have questions about which treatments would work best in your space, contact us today for a free assessment and consultation.

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A “Stand off” (clip) is a good thing.

When people order acoustic panels, whether it be Sonora Panels®, Tone Tiles®, or Silent Pictures®, the mounting method is sometimes overlooked.

“A panel mounted to the wall is a panel mounted to the wall… right?”
This isn’t entirely accurate, and we are going to focus this installment on the often misunderstood Stand off clip.

2″ Stand off Clips

What makes the Stand off clip different is that it doesn’t hold the panel flush to the wall, but it leaves a gap between the wall and the panel.

Why would you want this?
There are a few very important reasons, both acoustic and aesthetic.

Sonora® Panels with 2″ Stand off clips.

Acoustically.
Sound travels around all exposed surfaces, and by raising the panel off the wall, you expose the back surface to sound, more like a baffle, which is a great absorber.  Also, sound will pass through a panel into the space behind, bounce off the wall, and then have to pass through the panel again.  This transition from panel to air and back changes the medium sound must travel through – this effectively changes impedance, which strips energy from sound. These are just a couple of the acoustic benefits of using a standoff clip – there are others.

Tone Tiles® and Silent Pictures® can be mounted with Stand off Clips.

 

Sonora® Panel back-lit on Stand off Clips

Aesthetically.
Wall mounted Sonora® panels take on a whole new dimension when using Stand off clips – they appear to float in mid air a couple of inches off the wall.  This alone adds visual interest to a standard panel, but it can then be further accented by back-lighting the panel – changing the simple panel into a focal point in the lighting scheme.

Stand off clips can also be used with Tone Tiles® or Silent Pictures® – allowing your artwork to literally jump off the wall and float in the space in front of it.

So, a stand off is a good thing, with Sonora® Panels, Tone Tiles® and Silent Pictures®acoustically and aesthetically.

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University of Miami – Frost School of Music

Students at the Frost School of Music had an “ear-opening” experience when their Computational Psycho-acoustics class was lectured by Jim DeGrandis of Acoustics First last month.  The topics ranged from engineering to human perception of ultrasonic frequencies. The students were exposed to concepts and demonstrations of ultrasonic frequencies which have been modified in ways to make them audible, and ultrasonic anomalies affecting the audible range in ways that are very blatant and obvious.

One of the most stark examples of “audible ultrasound” being the demonstration of a Parametric Speaker, which modulates the ultrasonic carrier to produce very directional audible frequencies.

Computational Psycho-Acoustics at Frost School of Music – University of Miami. Dr. Chris Bennett (far left) and Jim DeGrandis (in signature cap – center) [photo credit: Gonzalo Mejia]

Jim also spoke at the student forum about misconceptions of what it really means to be “in the industry” …and did an encore demo of the Parametric Speaker – which had apparently been such a novel experience for the Psycho-Acoustics class that they ‘demanded’ it be experienced again by a wider audience. (and it was just plain fun!)

 

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