Science of Music: Room Acoustics Problems

INART 50 Science of Music
Room Acoustics Problems
1)
Think back to high school, the dances in the gym, and the sound of the bands that played
for those dances. Why did the bands always sound so loud and indistinct? Why did they
sound better once it got more crowded inside? Speaking of that gym, when they used to
show movies in there, why could you never understand the dialogue?
2)
You’re recording your band in your garage, and find that the sound has way too much
bass. The band considers lining the room in wood, hanging heavy curtains, and putting
up sheets of thick plaster. Discuss the possible effect each choice would have on the
band’s sound.
3)
What is the reverberation time and reverberation radius for a room without furniture that
is 20m x 15m x 13m?
4)
What is the reverberation time and reverberation radius for a room without furniture that
is 300 ft x 75 ft x 15 ft?
5)
You are recording in a room with an absorption surface area of 10,000 square feet.
You’ve placed the microphone 20 feet away from the sound source. You want to capture
a good sense of the room’s reverberation. Are you likely to get a more reverberant
recording by moving the microphone farther away? If you point it away from the sound
source? Discuss why or why not.
6)
You and a companion go to the park one afternoon and hear a lovely outdoor concert.
Afterward, your companion asks you, “What advantage does that bandshell 30 ft. above
and behind the stage have over a stage sitting out in the open? We heard that concert last
week with a shell that was 60-ft, and it didn’t sound nearly as good.” Given your
knowledge of early reflections, how do you answer?7)
You are in charge of renovations to your school’s auditorium. A school board member
who dabbles in acoustics suggests that the side walls be angled slightly away from the
stage, and that they be lined with rounded protrusions that are offset on the left and right
walls (see below). Since you must do the school board’s bidding, consider whether this
be an effective design. What are the considerations?
stage
8)
As discussed in class, not all presentations are appropriate for all venues. An example of
particular focus was music written for the Church, which was the primary patron of the
arts in earlier centuries. Discuss why church music is best heard in churches, rather than
concert halls. Why would a space be suitable for a spoken lecture, but not for music (or
vice versa)?
9)
Describe the filtering that might result in a room with parallel reflective walls that are
twelve feet apart.