2. The environment of the bathroom is different from other rooms. Limited space and articles in the bathroom can make the sound reflection effect reach an excellent state. The walls of the bathroom are smooth and solid, the washbasin and bathtub are hard, and the big floor is not covered. These planes are ideal high-frequency reflecting surfaces. The sound that people make when they sing is a high-frequency sound. High-frequency sound is easy to attenuate when propagating because of its long wavelength, and low-frequency sound is easy to diffract and not easy to attenuate because of its short wavelength. In an ordinary room, high-frequency sound is easily absorbed by various items placed in the room and easily attenuated, while low-frequency sound will remain.