Doppler distortion

The Doppler effect can have a detrimental effect when listening to music when a single cone emits different frequencies simultaneously e.g. with music. If the cone is oscillating at a frequency of 50 Hz, for example, and, at the same time, it is required to produce a frequency of 1000 Hz, this will create modulation as the higher frequencies is superimposed on the lower. The 1000 Hz tone will thus change 50 times per second. This will produce rough sounding tones, similar to the fast wow and flutter perceived sometimes with tape recorders. The stronger the cone excursion, the more noticeable the Doppler effect is - in other words it increases as the low bass becomes stronger.