Fundamentals of Architectural Acoustics

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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!

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