It may shock you to learn that the initial applications for sidechain compression in the 1930s were not directed at making French filter house. Rather, it started with a film audio engineer named Douglas Shearer, who needed a way to tame the sibilance (the hard “s” sounds) of dialogue recordings. Sidechaining was born when Shearer conceived of a compressor with a “side” signal chain (separate to the main trigger signal) with an EQ slapped on it – rather than evenly compressing the incoming signal, this “de-esser” would only be triggered when the specific sibilant sounds appeared.