Avid Blogs: Understanding the Audio EQ Tool

Avid Blogs by Benjamin Hershleder

Now, this isn’t going to be an entire section on everything about sound. I’ll leave that to the experts. But what I can do is give you a general understanding of what the EQ Tool is allowing you to adjust. But that means giving you a bit of background on a few things before we get to the tool.

Frequency Basics Overview

Equalization (“EQ” for short) is essentially reducing or increasing the volume level of certain frequencies in an audio signal to make them less prominent or more prominent (quieter or louder). What is a frequency? Well, that term refers to how many regular fluctuations (a.k.a. “oscillations”) of a sound wave occur during one second. If there are very few waves per second (a low frequency), then the sound is a low note. If there are a lot of waves per second (a high frequency), then the sound is a high note.

Anything that occurs at a regular rate (a number of “somethings” happening in one second) can also be described as a cycle. For example, a piston in your engine moving up and down does this a specific number of times each second, in other words in cycles. Each sound wave can also be described as a cycle. It has a beginning, a middle and an end; and then it repeats again, and again, and again. However, when we talk about sound, we generally don’t say “Waves per second” or “Cycles per second.” Instead, we use the term Hertz (abbreviated as Hz), which is named after the German physicist Heinrich Hertz. For emphasis: “Cycles per second” and Hertz are the same thing. Hertz are used to describe various phenomena that occur at a regular rate. You’ve likely heard the term Hertz used before to describe electricity (e.g. 50 Hz or 60 Hz), and I imagine you’ve heard it used to describe the processing speed of a computer (e.g. 3 GHz). Computers are so fast today that we don’t relate the speed in terms of just Hertz, but instead in terms of billions of Hertz, which are called Gigahertz (abbreviated as GHz). OK, let’s get back to sound. Below is an animated picture of sound wave frequency in one second, and you can see in the top right of the image (below) how the number of Hz increases as the number of waves increases. read more...