Question

If you sandwich a good (90% efficiency) sound absorbing material together with a good (90% efficiency) sound reflecting material and you direct the sound at the sound reflecting side of the panel - what will be the effect?

Answer 1

If you sandwich a good sound-absorbing material together with a good sound-reflecting material and direct the sound at the sound-reflecting side of the panel, the overall effect will depend on the specific properties and arrangement of the materials.

Assuming the sound-absorbing material has a high absorption coefficient (90% efficiency) and effectively absorbs the incident sound energy, and the sound-reflecting material has a high reflection coefficient (90% efficiency) and reflects most of the incident sound energy, the following effects can be expected:

1. Sound absorption: The sound-absorbing material will absorb a significant portion of the incident sound energy that reaches its surface. This will result in a reduction of the sound intensity or amplitude as the absorbed energy is converted into heat or other forms of energy. The sound-absorbing material will help attenuate the sound and reduce its reflection back into the environment.

2. Sound reflection: The sound-reflecting material, with its high reflection coefficient, will reflect a significant portion of the incident sound energy back into the environment. This reflection will result in the sound bouncing off the panel, potentially creating echo or reverberation effects depending on the environment and the distance between reflective surfaces.

The overall effect will be a combination of sound absorption and sound reflection. The sound-absorbing material will reduce the intensity of the incident sound by absorbing a significant portion of it, while the sound-reflecting material will reflect a portion of the incident sound back into the environment.

It's important to note that the specific acoustic properties and efficiency values of the materials, as well as the arrangement of the panel, will affect the exact outcome. The effectiveness of the panel in attenuating sound and controlling reflections will depend on factors such as the frequency of the sound, the thickness and composition of the materials, and the overall acoustic environment in which the panel is placed.