Indoor acoustic field

The sound waves from an outdoor source are continuously propagated outward in the form of spherical waves. With the increase of the distance between the receiving point and the source, the sound energy decreases rapidly. In this case, the sound energy emitted by the sound source is transmitted to the distance without hindrance, and the sound energy density of the receiving point is inversely proportional to the square of the sound source distance, that is, the attenuation of 6dB for every 1fold increase of the distance is very simple.

In the enclosed space such as the auditorium, gymnasium, classroom and broadcasting room, sound waves will be reflected and absorbed by each interface (wall, ceiling, ground, etc.) of the enclosed space when they propagate. The overlapping of sound waves forms a complex sound field, namely the indoor sound field, and causes a series of unique acoustic characteristics.

Characteristics of an indoor sound field

1. At a receiving point at a certain distance from the sound source, the sound energy density is higher than that in the free sound field, and usually does not decay with the square of the distance.

2. After the sound source stops making sounds, in a certain period of time, there are late reflected sounds from various interfaces in the sound field, resulting in the "reverberation" phenomenon.

In addition, due to the resonance with the room, it causes certain frequencies of the room sound to be strengthened or weakened. Due to the shape of the interior and the arrangement of interior decoration materials, echoes, vibrating echoes and other special phenomena are formed, resulting in a series of complex problems. How to control the shape of the room and the distribution of sound-absorbing and reflective materials so that the room has a good sound environment is the main purpose of interior acoustics design.