Simple Explanation

Extra, unwanted tones added to a sound when it goes through electronics or speakers, making it less clean.

Concise Technical Definition

The unintended addition of harmonic frequencies to a signal due to non-linearity in audio components; measured as a percentage of the original signal.

Layman-Friendly Analogy

Like hearing a singer’s voice with a faint, unwanted echo layered behind it—it muddies the original.

Industry Usage Summary

Expressed as Total Harmonic Distortion (THD) in specs; lower THD indicates higher audio transparency. Common in amps, DACs, and speakers.

Engineering Shortcut

Output includes harmonic multiples; THD = √(sum of harmonic powers²) / fundamental.

Full Technical Explanation

Harmonic distortion occurs when a system introduces additional frequency components at integer multiples of the fundamental frequency due to non-linear behavior. It is present in all real-world audio systems to some extent and is often quantified using THD (Total Harmonic Distortion), which expresses the sum of all harmonic content (usually through a defined order, such as the 8th harmonic) relative to the original signal as a percentage. A true THD value involves computing the square root of the sum of the squares of the amplitudes of individual harmonics. Lower harmonic distortion generally means a more accurate and transparent reproduction of sound, though certain types (like low-order even harmonics) may be perceived as warm or musical.