The Complete Handbook of Noise Gates & Compressors

Chapter 1: Understanding Noise Gates & Compressors

Every audio signal is a mixture of two things: the sound you want to hear, and the artifacts you would rather not. A guitarist's string ringing into a loud amplifier produces a hiss and hum before a note is even played. A vocalist's breath, mouth noise, and the rumble of an air conditioning unit all land on the microphone along with the voice. A bassist's uneven playing will cause the low end to swell and dip in a way that is difficult to mix. These are not exotic problems; they are the daily realities of working with sound. The tools designed to control these issues, the noise gate and the compressor, are not magic boxes that make a mix 'sound professional.' They are precise, often simple, instruments that perform a single, reducible function: they automatically adjust the level, or gain, of a signal based on set criteria. Once you understand that core function, you can put them to work in a hundred different scenarios, from the cleanest classical recording to the most aggressive rock concert.

Let us be clear from the start about what a compressor does. It reduces the dynamic range of a signal. Dynamic range is the difference between the loudest and quietest parts of an audio source. The compressor does this by automatically turning down the volume when the signal exceeds a specific level, which we call the threshold. Imagine a broadcaster speaking on air. In a passionate segment, their