Audio Fundamentals
IM distortion occurs when two or more audio frequencies interact within an amplifier, converter, or other component, producing additional unwanted frequencies that were not present in the original signal.
IM distortion (Intermodulation distortion) differs from harmonic distortion, which generates multiples of a single tone. Instead, IM distortion creates sum and difference tones from the original frequencies, often producing dissonant or harsh-sounding artefacts that degrade the clarity and naturalness of the audio. For example, if 1 kHz and 1.2 kHz signals are present, IM distortion can produce unwanted tones at 200 Hz and 2.2 kHz.
High-quality audio equipment is designed to minimise IM distortion through precise circuit design, linear amplification stages, and low-feedback topologies. The level of intermodulation distortion is typically expressed as a percentage or in decibels, with lower values indicating greater linearity and transparency. Reducing IM distortion is critical for maintaining accurate stereo imaging, tonal integrity, and overall fidelity in professional audio systems.
