What is the difference between structure-borne and airborne noise?

In simple terms, the difference between structure-borne and airborne noise lies in the transmission medium. Airborne noise consists of the progressive movement of mass particles (vibrations) and is transmitted in the form of sound waves at the speed of sound (344m/s). The differing frequencies (the number of changes in pressure per second) generate characteristic tones. For example, whistling has a high frequency, compared to the low frequency generated by a growl of distant thunder. Frequencies are measured in Hertz (Hz). The audible range of a healthy young person extends from approx 20 Hz to approx. 20 kHz (20,000 Hz). Structure-borne noise is transmitted through solid structures, such as steel, wood, concrete, stone etc. This includes for example impact sound and part of the noise generated by the technical machinery installed in a building. The unit of measurement for describing sound is the decibel ("dB").