Noise Control "How Tos" & Installation Articles.., Noise Control Questions

Sound is vibration transmitted through a medium. When we think and talk about sound, though, we mean those vibrations in air molecules that can be picked up by human ears.

Sound as a Wave

Sound energy moves the molecules within the substance through which it travels, just like ripples in a pond. Sound waves spread in a circle from the source, becoming less intense with distance.

Sound is like water. It doesn’t have a shape or form, but molds itself to its surroundings. And like water, sound can be absorbed by some materials and contained by others.

Sound waves need a medium through which to travel. There’s no sound in space, and the most common sound conductor on earth is air. But sound waves can also pass through solid materials. Which is why Soundproof Cow is in business!

How is Sound Measured?

You can look at water and see that either the surface is smooth, or it has a lot of big waves. You can even pour it into a container and measure it. Since sound doesn’t look like anything, how can you tell how “big” or “loud” it really is?

Sound is measured in two fundamental ways: frequency and amplitude, or as they are more commonly known, pitch and volume.

Frequency

Frequency, also known as pitch, is the space between waves of sound, or how many times a sound wave oscillates (moves up and down) in one second. The frequency of a sound is like the current in a body of water. The current tells you how fast the water is moving from one point to another.

Frequency is expressed in Hertz (Hz). Hertz is a measure of frequency per unit of time. For example 1 Hertz = 1 sound oscillation per second. The average person can hear sounds with frequencies between 60Hz and 23000Hz. The average cow can hear sounds with frequencies between 20Hz and 35000Hz.

A high-pitched sound is like a ripple in a pond: it’s small, has low power, moves quickly and can easily be controlled and redirected. A low-pitched sound is more like a tsunami or tidal wave: large, slow moving, strong and difficult to control or redirect.

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