ECE Acoustics Q&A

1. When waves bend away from straight lines of travel, it is called _______.
A. reflection
B. defraction
C. rarefraction
(D) refraction
2. Required time for any sound to decay to 60 dB.
A. Echo time
B. Delay time
(C) Reverberation time
D. Transient time
3. The intensity needed to produce an audible sound varies with _________.
(A) frequency
B. noise
C. amplitude
D. tone
4. Sound that vibrates at frequency too high for the human ear to hear (over 20 kHz).
A. Subsonic
B. Transonic
(C) Ultrasonic
D. Stereo
5. The thin springy sheet or bakelite or metal that permits the voice coil in a dynamic
loudspeaker to move back and forth along the core of its magnet.
A. Vibrator
B. Diaphragm
C. Hypex
(D) Spider
6. What is the dB SPL of an auditorium with contemporary music?
A. 90
(B) 85 – 90
C. 95 – 100
D. 100 – 105
7. Intensity can also be called as
A. volume
(B) loudness
C. sharpness
D. strength
8. The loudness of a sound depends upon the energy of motion imparted to
__molecules of the medium transmitting the sound.
A. transmitting
B. running
C. moving
(D) vibrating
9.__________is affected by the distance between the listener and the source of
the sound and its intensity varies inversely with the square of this distance.
A. volume
B. bass
C. treble
(D) loudness
10. If the distance between the listener and the source of the sound is doubled, the
intensity is reduced to
A. ½
B. 1/3
C. 2/3
(D) ¼
11. An instrument designed to measure a frequency-weighted value of the sound
pressure level.
(A) Sound level meter.
B. Transducer
C. Sound pressure meter
12. A unit of noisiness related to the perceived noise level
(A) Noy
B. Sone
C. dB
D. Phon
13. 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 curve
(C) Noise rating curves
D. F1A weighting curve
14. The frequency of a free vibration.
A. Resonant frequency
(B) Natural frequency
C. Center frequency
D. Normal frequency
15. The transmission of sound from one room to an adjacent room, via common
walls, floors or ceilings.
(A) Flanking transmission
B. Refraction
C. Reflection
D. Reverberation
16. The 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
17. Velocity of sound in air.
A. 300 m/s
(B) 330 m/s
C. 1130 m/s
D. 344 m/s
18. Speaker is a device that
A. converts sound waves into current and voltage
(B) converts current variation into sound waves
C. converts electrical energy to mechanical energy
D. converts electrical energy into electromagnetic energy
19. Which type of microphone operates on the principle that the electrical
resistance of carbon granules varies as the pressure on the granules vary?
A. Dynamic
B. Crystal
(C) Carbon
D. Ribbon-type
20. Bass response is
A. maximum high frequency response
B. emphasizing the high audio frequencies
(C) bypassing high audio frequencies
D. bypassing low audio frequencies
21. Pure tone of sound used as standard on testing.
A. 1 Hz
B. 10 Hz
C. 100 Hz
(D) 1000 Hz
22. _______ is early reflection of sound.
(A) Echo
B. Reverberation
C. Pure sound
D. Intelligible sound
23. Noise reduction system used for him sound in movie.
(A) dolby
B. dBa
C. dBx
D. dBk
24. 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
25. _________ is the unit of loudness level of a sound.
A. Sone
B. Decibel
C. Mel
(D) Phon
26. _________ is the average rate of transmission of sound energy in a given
Direction through a cross-section area of 1 sq. m. at right angles to the direction.
A. Sound pressure
B. Loudness
(C) Sound intensity
D. Pressure variation
27. What is the unit of pitch?
A. Sone
B. Phon
C. Decibel
(D) Mel
28. A measure of the intensity of sound in comparison to another sound intensity.
A. Phon
(B) Decibel
C. Pascal
D. Watts
29. Sound wave has two main characteristics which are
A. highness and loudness
B. tone and loudness
(C) pitch and loudness
D. rarefraction and compression
30. Which type of microphone operated by electromagnetic induction that
generates an output signal voltage?
A. Carbon
(B) Dynamic
C. Crystal
D. Condenser