totalharmoniskdistorsion

Total harmonic distortion (THD) is a measure used in electronics and acoustics to quantify the amount of harmonic distortion present in a signal. Harmonic distortion occurs when a signal contains frequencies that are integer multiples of the fundamental frequency, often due to non-linearities in amplification or processing. THD is expressed as a percentage or decibel (dB) value, representing the ratio of the sum of all harmonic components to the amplitude of the fundamental frequency.

In audio systems, THD is particularly relevant as it affects sound quality. Non-linear components, such as amplifiers, speakers, or analog recording equipment, can introduce harmonic distortion when processing signals. For example, clipping—a common form of distortion—occurs when an amplifier’s output exceeds its maximum capacity, producing unwanted harmonics. While some distortion can be desirable in certain musical contexts (e.g., guitar amplifiers), excessive THD degrades audio fidelity by introducing artifacts like harshness or coloration.

THD is typically measured using a test signal, such as a sine wave, and analyzed via a spectrum analyzer or distortion meter. The total harmonic distortion *plus noise* (THD+N) accounts for both harmonic distortion and background noise, providing a more comprehensive assessment of signal integrity. Lower THD values indicate better signal purity, with professional audio equipment often targeting values below 0.1% for high-fidelity applications.

In electronic systems, THD can also impact performance in communication, power supplies, and signal processing. Mitigation strategies include using high-quality components, proper biasing, and feedback mechanisms in amplifiers to reduce non-linearities. Standards for THD vary by application, with stricter tolerances required in precision audio and telecommunications.