Harmonic Processing

Image artifacts are reduced in harmonic imaging. Most artifacts are produced in the near field. Since harmonic signals are very low in the near field, the image artifacts do not generate harmonics. There is little or no harmonic energy in the near field or at the far edges of the acoustic field, and as a result the majority of image artifacts are contained only in the fundamental frequencies.

Harmonic frequencies are not produced in the near field because the wave has not traveled far enough for distortion to occur. Image artifacts are low in energy. Higher amplitude sound transfers more energy to harmonics. So, by filtering out the fundamental frequencies, the majority of image artifacts are filtered out as well.