Building Services Engineering 5th Edition Handbook

348 Room acoustics
55. Which is not correct about reverberation time:
1. When short, below a second, room seems lively.
2. Long reverberation time causes room to sound noisy and echoes.
3. A lecture theatre needs a short reverberation time.
4. A large volume car-manufacturing building has a long reverberation time.
5. When short, below a second, room seems dull.
56. Which is not correct about an anechoic chamber?
1. Used to measure sound power level from acoustic sources such as fans and compressors.
2. Must have no reverberant sound field.
3. Lined with fully absorbent foam wedges.
4. Sounds perfectly dull.
5. Used to measure reverberant field sound pressure level from acoustic sources such as
fans and compressors.
57. What does natural frequency of vibration mean?
1. Damped vibration.
2. Strike a guitar string and it vibrates at up to four times its natural frequency depending
on volume of sound box.
3. Bounce a coil spring and it vibrates at its natural frequency of vibration.
4. A frequency mechanically forced upon an item, such as by a motor.
5. A material never vibrates at this frequency.
58. Which does NR stand for?
1. Noise resonance.
2. Normal rating.
3. No resonance.
4. Noise ratification.
5. Noise rating.
59. How are noises related to human ear response?
1. Humans respond to sound power level within a range of audible frequencies.
2. Humans respond to loudness produced over a range of audible frequencies.
3. Sound pressure levels are added to create an overall relationship to ear response.
4. Sound power levels are added to create an overall relationship to ear response.
5. Loudest sound at any frequency is taken as ear response.