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Fundamentals of Architectural Acoustics

Maximize Your Space

No matter what kind of equipment you’re using, the space they are in determines sound performance more than anything else. The size and shape, levels of absorption and reflection, even the materials used in construction all affect the way sound waves move through a space.

This science of sound is a dense subject, but a few fundamentals can help you understand how sound waves behave, and what parts of your space are helping – and hurting – what you hear.

Frequencies and Waves

Sound is measured in frequencies (Hz), which travels in the form of waves. The higher the frequency, the higher the pitch! Higher pitches (or higher frequencies) have a much shorter wavelength than lower frequencies/pitches. This affects how the sound waves travel, and one of the reasons you can hear lower pitches (bass) at a further distance from the sound source.

It’s important to keep these things in mind when you’re doing acoustic treatment, or just when listening to how a particular room sounds. The larger wave forms of lower pitches cover more distance with each cycle, so the bass in the back of a room may be drastically different than right near a subwoofer or amplifier (for just one example).

Reflection vs. Diffusion

When sound waves hit a surface, they behave in a variety of ways. When they “bounce,” it is typically with either reflection or diffusion. Sound waves reflect when they strike a flat surface and bounce back in the same direction. Because a tiny fraction of the energy is lost, the reflected frequency is quite identical – this leads to overtones and distortion within the nearly identical sound waves, and is the primary reason that large, flat surfaced rooms sound harsh to the ear.

Alternatively, when sound waves strike rounded or uneven surfaces, they are diffused – meaning the are “bounced” in multiple directions. Since they don’t reflect exactly back on themselves, there isn’t interference among the waveforms. This is why you see acoustic treatment with textured surfaces, or why rooms with many angles and objects tend to sound “warmer” or less harsh.

Absorption

Sound waves are also absorbed by the objects they hit. Different materials offer different levels of absorption, and frequencies ranges behave in their own unique waves. Higher frequencies are more easily absorbed, while lower frequencies can pass through objects. This means that lower frequencies often far more difficult to control. Absorbent materials, like foam, sound absorbing panels, etc. certainly help, but those large waves have to go so somewhere!

There are sophisticated devices and calculations for determining materials absorb what frequencies, and all of these come into play when designing a room with acoustics in mind – or simply adding treatments to a space to improve acoustic properties.

More Resources

In fact, the science of sound is far more than high and low pitches, or what direction your speakers are pointing. It’s math and physics, vibrations in the air moving at incredible speeds and behaving in fascinating, complex ways. For many audio engineers, getting a handle on the basics of acoustics – especially within rooms – is important to mastering their equipment. For architectural acoustic designers, it’s an entire world of study… And for physicists, it’s even deeper!

For a deeper long (and much of the math) explore these resources:

Technicon Acoustics – Acoustics 101
Basic Guide to Architectural Acoustics
USG – Understanding Acoustics in Architectural Design

For questions about your space – and how to improve its acoustics, contact Sound Connections Group today!

Live Sound Tips from Sound Connections Group - SCGAV.com

Tips for Live Sound

5 Top Tips

Mastering the art of live sound engineering is no small undertaking. Every room and every system is unique. There’s a laundry list of terms to memorize and different functions to get familiar with…

That said, there are some basic principles that can go a long way with any mix. You’ll learn as you go, picking up tips and tricks and developing your own workflow. These basic ideas can help you go from a meat and potatoes approach to something a little more nuanced. As you learn and grow, you’ll find more and more uses for effects and the features of your console, but these starting points will help set you on the right path!

Go Easy on The Reverb

Reverb is a great way to add body to vocals and help them stand out – but too much gets problematic (to say the least). If you’re cranking up the reverb, not only will lyrics lose some of their definition, you also run the risk of feedback.

Start small, and gradually increase reverb to add color. Go easy at first and bring it up to a subtle, almost unnoticeable level. A little bit goes a long way!

Subtractive Mixing

Boosting frequencies isn’t the only way to EQ your overall mix! Many novice engineers make the mistake of only bringing up frequencies, maxing things out until there’s no more headroom. If everything is boosted – nothing is!

Instead, try a subtractive approach, pulling frequencies away from channels to bring others out. It may take a little while to get the hang of, but this method leaves you more “wiggle room” to adjust as songs change, and stops you from cranking everything to 11!

Gates for Toms

If you’re putting mics on toms (which may only sometimes be necessary), it’s generally a good idea to use gates to set a threshold of sustain. Toms can be boomy to begin with, and when they’re coming through the PA, a long, sustained pitch can muddy up the rest of the mix – and just sound bad to listeners.

Use gates to keep the tom sound relatively short. Let the attack and tone come through, but shut it down after a clear pitch has been pronounced. Again, you’ll find the right threshold for the room you’re working in with some experience, and develop some rules of thumb that work with your workflow. Regardless of where you decide to set your gates, they’re a good idea to use whenever you’re amplifying a drum set’s toms!

Mute Your Channels!

This is live sound 101. When the set is over, MUTE THE CHANNELS. This should be the very first thing you do when a band or artist is finished playing. If you hit those mute buttons right away, there’s no chance for that awful popping sound as a performer unplugs a guitar. You won’t hear chatter through the vocal mics either.

There isn’t much more to it than that. Muting your channels at the end of a set is critical. Do it every time.

Plan for The Worst

Like any other job, things can go wrong. Batteries in wireless mics can die, DI boxes can fail, cables can go bad… So plan for the worst! Have extras on hand if you can, and put a backup plan in place should things go terribly wrong. Particularly for vocalists, it’s not a bad idea to have another mic ready to go at the side of the stage.

If you can anticipate it, plan for it! Know the pieces of the system you’re working with, and have as many contingencies in place as possible. You won’t be able to repair every problem on the fly, but the more prepared you can be, the better.

This is just a small slice of all there is to know. Experience and study will be your best friends as you learn the ropes of live sound. Always start simple and work toward complexity. If you’d like deeper training on mixing live, contact Sound Connections Group today!