Direct transfer

Professional Definition

This is a method of transmitting acoustic energy, in which sound travels from the transmitting room to the receiving room solely through the element separating these rooms (e.g., a partition wall or ceiling), without the involvement of side paths. The sound insulation value for direct transmission mainly depends on the surface mass of the partition, its stiffness, and airtightness.

“In the computational model of acoustic insulation, direct transmission is the dominant component only when lateral (flanking) transmission is minimized.”

Acoustics in Simple Words

Imagine a dam on a river. The water that seeps through cracks in the dam wall itself is analogous to direct transmission. The water that flows around the dam, soaking into the ground at the edges, is lateral transmission. If you want to seal the dam (soundproof a room), the first step is to patch the holes in the wall itself. However, if the wall is solid and water continues to flow, you need to address the edges. In acoustics, if the wall is as thin as paper, then direct transmission accounts for 90% of the noise you hear.

Summary

Direct transmission concerns the shortest path of sound through the separating partition. Its limitation is the first and most important step in acoustic insulation, usually achieved by increasing the wall mass or using multilayer structures.