Test Yourself - Acoustics

1. Speaker is a device that

a) converts sound waves into current and voltage
b) converts current variations into sound waves
c) converts electrical energy to mechanical energy
d)converts electrical energy into electromagnetic energy

2. Which type of microphone operates on the principle that the electrical resistance of carbon granules varies as the pressure on the granules vary?

a)Dynamics
b) Crystal
c) Carbon
d) Ribbon-type

3. An instrument designated to measure a frequency-weighted value of the sound pressure level.

a) Sound level meter
b) Transducer
c) Sound pressure meter
d) Sound analyzer

4. The frequency of a free vibration

a) resonant frequency
b) natural frequency
c) center frequency
d) normal frequency

5. The transmission of sound from one room to an adjacent room, via common walls, floors or ceiling.

a) Flanking transmission
b) Refraction
c) Reflection
d) Reverberation

6. A unit of noisiness related to the perceived noise level

a) Noy
b) Sone
c) dB
d) Phone

7. An agreed set of empirical curves relating octave-band sound pressure level to the center frequency of the octave bands.

a) C-message weighting curve
b) Psophometric weighting curve
c) Noise rating curve
d) F1A weighting curve

8. A measure of threshold of hearing , expressed in decibels relative to a specified standard of normal hearing.

a) Hearing loss
b) Sensation level
c) Hearing level
d) Sound pressure level

9. A certain machine with a slightly out-of-balance motor rotating at 1800/min is fixed on a perfectly elastic mount with a static compression of 2.50 mm. Calculate the resonant frequency of mount.

a) 1o Hz
b) 20 Hz
c) 30 Hz
d) 40 Hz

10. Calculate the lowest resonant frequency for a brick partition 120 mm thick, 4 m by 2 m in area with longitudinal wave velocity of 2350 m/s. (Assume that it is supported at its edges).

a) 1o Hz
b) 20 Hz
c) 30 Hz
d) 40 Hz

11. Velocity of sound in air.

a) 300 m/s
b) 330 m/s
c) 1130 m/s
d) 344 m/s

12. Bass response is

a) maximum high frequency response
b) emphasizing the high audio frequencies
c) bypassing high audio frequencies
d) bypassing low audio frequencies

13. _______ is early reflection of sound.

a) Echo
b) Reverberation
c) Pure sound
d) Intelligible sound

14. Noise reduction system used for film sound in movie.

a) dolby
b) dBa
c) dBx
d) dBk

15. What is the sound energy per unit area at right angles to the propagation direction per unit time?

a) Loudness
b) Coherence
c) Sound pressure
d) Sound intensity