Audio signal processing

In between getting excited about sound signals and wondering whether I should get out more, I often use audio effects. Audio “signal processing” is essentially just a technical term for effects applied to an audio signal, and there are many of these, and many detailed ways of exploring them further and in various software programmes, but for now here’s a quick guide just to understanding the basics of what two of the most useful effects are, for basic audio improvement.

Compressor limiters: These reduce the dynamic range of audio – i.e. reduce how great the difference in volume is between the quieter parts and the louder parts – so this can be useful if you’ve recorded an interview with one person talking very loudly and one person with a much quieter voice. Put simply, using a compressor means you can bring the level of the recording up, whilst ensuring that the louder parts don’t get excessively loud. Limiters stop the sound exceeding a certain maximum level, but that kind of cut-off can sound quite unnatural, so compressors are often used to gradually reduce the increase in sound as it gets closer and closer to that level. These settings can all be customized with what we call “thresholds” and the ratio of compression – more info on that if you want it.

EQ (short for “equalization”): This increases or decreases the amount of certain frequencies (pitches) within the sound. This is useful during a windy interview, for example, when you can reduce how much the wind’s frequency (pitch) is heard. This can also effect the speech, however, so use with caution (see below). Again, more info on this effect if you want it. The term “flat” refers to sound without any EQ applied.

With both of these effects, it’s important not to “over process” the sound by applying too much of the effect, as this can result in your audio sounding unnatural, but they can be very useful effects too. Essentially, your ear is the best guide!

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