PHYS

Homework 4

Due: Wednesday 10/14/20 at 5:00PM

1- Assume you have a normal or an average hearing. You hear a guitar being played at frequency of 90 (Hz) with sound loudness level of 50 (Phon).

According to the following Fletcher-Munson Diagram, what is the actual sound intensity level of the guitar being played?

2- The frequency of musical note E3 is equal to 164.81 (Hz).

A- Calculate the frequency of three octaves lower than E3 note which is E0

B- Calculate the frequency of five octaves higher than E3 note which is E8

3- Assume you are trying to measure the reverberation time in the lab. You strike a soundwave with sound intensity level (SIL) of 98 (dB) in the lab.

A- What would be the sound intensity level (SIL) of this soundwave at the reverberation time?

B- What would sound intensity (I) of this soundwave at the reverberation time?

4- The reverberation time in a rehearsal room is 0.98 second (S). If the effective absorption area of the rehearsal room is Se = 150 (m2).

A- What is the volume of rehearsal room?

B- If rehearsal room has the length of 12 (m) and width of 15 (m), calculate the height of the room.

5- The reverberation time of a room with volume of 210 (m3) is 2.4 (s) when the door of the room is closed. The door has a rectangular shape with sides of 1 (m) and 2 (m). The absorption coefficient (α) of the door is 0.3

A- Calculate the efficient absorption area (Se) of the room.

B- Calculate the reverberation time the room when the door is open (hint: when the door is open, it become perfect absorber and absorption coefficient becomes α = 1)