Good evening everyone Help me i n my hw ,The wall of cinema hall are covered with sound absorbing materials. Why?Answer it ASAP. Good day ​

The roof and walls of the auditorium or cinema hall are generally covered with sound absorbent materials like draperies or compressed fibreboard to reduce reverberation. These materials reduce the formation of echoes by absorbing sound waves.

c)as speed changes, wavelength and frequency change.

everything changes!

this is poiselle's equation from fluid mechanic in physics. mech eng