
Principles of Analog Electronics
354
The lower detectable value of harmonic distortion for a human ear is difcult
to evaluate, but it is considered to be around 0.3%. So, for practical aims an
amplier producing a THD higher than that value does not “guarantee” hearing
a “cleaner” sound.
Some recent studies demonstrated that many people consider “more
musical” a signal with 0.5% second harmonic distortion added.
Intermodulation distortion (IMD) occurs when two or more input frequencies
are applied in a nonlinear amplier. Intermodulation is intended as the production
of new components, termed intermodulation products, having frequencies cor-