NCIDQ IDFX Practice Exam

What is a recommended average absorption coefficient for a room to effectively control sound?

1. 0.1

2. 0.2

3. 0.5

4. 0.4

The correct answer is: 0.2

The recommended average absorption coefficient for a room to effectively control sound is generally around 0.2. This value indicates that 20% of sound energy is absorbed by the room's surfaces, which is considered adequate for balancing acoustic control without excessively dampening the sound. In interior design and acoustical planning, an absorption coefficient of 0.2 is often seen as a threshold that provides a reasonable level of sound absorption while still allowing for adequate reflection to support speech intelligibility and maintain a lively acoustic environment. This is especially important in spaces such as classrooms, offices, and meeting rooms, where clarity of sound is essential. An absorption coefficient significantly lower than 0.2, such as 0.1, would mean that most sound is reflected, leading to excessive reverberation, which can hinder communication and create an uncomfortable auditory environment. Conversely, coefficients higher than 0.2, especially values like 0.5, would indicate that over half of the sound energy is absorbed, which might result in a deadened sound quality and reduce the effectiveness of sound communication in the space. Therefore, an absorption coefficient around 0.2 strikes a balance between sound absorption and reflection.