efterklangstider

Efterklangstider, or reverberation time, is a fundamental acoustic parameter that describes how long it takes for the sound intensity in a room to decay by 60 decibels (dB) after the sound source has stopped. This decay is not instantaneous due to the reflections of sound waves off the surfaces within a space. The longer the reverberation time, the more "lively" or "echoey" a space will sound, as sounds persist for a longer duration. Conversely, a shorter reverberation time results in a drier acoustic environment.

The reverberation time of a room is influenced by several factors, primarily the volume of the space and the absorption characteristics of its surfaces. Larger rooms generally have longer reverberation times because sound waves have to travel further before encountering a surface. Materials that absorb sound, such as soft furnishings, carpets, and porous acoustic panels, reduce reverberation time. Hard, reflective surfaces like concrete, glass, and bare plaster increase it.

Efterklangstider is a critical consideration in the design of various spaces, including concert halls, theaters, lecture rooms, and even offices. In music venues, a controlled reverberation time is essential for achieving a desired musical quality. For speech intelligibility, a shorter reverberation time is generally preferred. Acoustic engineers use calculations and measurements to determine and adjust the reverberation time to optimize the acoustics for the intended purpose of a space. The Sabine formula is a well-known method for estimating reverberation time.