Sound waves can be transmitted perfectly over a distance of several metres (crosstalk effect) through a rigid ventilation pipe with a suitable cross-section (diameter of about 10 cm). Bends and bifurcations only have a slightly damping effect: without any preventive measures, a supply air network would function perfectly as a “house telephone”; in the living room it would be possible to hear every word spoken inside the bedroom and vice versa.

This effect can be easily corrected by means of crosstalk sound attenuators. These can consist, for example, of a duct section with membrane walls, which enables sound waves to leave the duct. The difference in the sound level between the inlet and outlet section is known as the insertion loss.

In a professionally executed ventilation system, at least one crosstalk silencer is integrated into the ductwork between two rooms.