What is the purpose of a speech processor in a transceiver?

A speech processor is designed to increase the average power of a Single Sideband (SSB) signal. Human speech has a wide dynamic range, meaning it has sharp peaks and deep valleys in volume. Because an SSB transmitter's power output is directly tied to audio input, quiet syllables result in low power output. A speech processor compresses this audio, bringing the quieter parts of your speech up in volume and clipping the excessive peaks. This drastically increases the "apparent loudness" or "punch" of your signal at the receiving end, helping you be heard through static or pileups. However, this process heavily alters the audio wave. Far from preventing distortion or making a signal sound "more natural," aggressive speech processing actually reduces natural fidelity and can introduce noticeable distortion if overused.