Acoustics 1. An instrument designed to measure a frequency-weighted value of the sound pressure level.
a. Sound-level meter b. Transducer c. Sound pressure meter d. Sound analyzer
7. A certain machine with a slightly out-ofbalance 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.
2. A unit of noisiness related to the perceived noise level
a. Noy b. Sone c. dB d. phone
8. Calculate the lowest resonant frequency for a brick partition 120 mm thick, 4m by 2min area with longitudinal wave velocity of 2350 m/s. (Assume that it is supported at its edges.)
3. An agreed set of empirical curves relating octave-band osund pressure level to the center frequency of the octave bands
a. C-message weighting curves b. Psophometric weighting curves c. Noise rating curves d. F1A weighting curves
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 ceilings.
a. Flanking transmission b. Refraction c. Reflection d. Reverberation
6. A measure of threshold hearing, expressed in decibels relative to a specifoed standard of normal hearing.
a. Hearing loss b. Sensation level c. Hearing level d. Sound pressure level
a. 300 m/s b. 330 m/s c. 1130 m/s d. 344 m/s
10. What is the expected critical frequency for a 120 mm thick brick wall? Assume a longitudinal wave velocity in brick of 2350 m/s and that the velocity of sound in air is 330 m/s.
a. 10 Hz b. 20 Hz c. 30 Hz d. 40 Hz
9. Velocity of sound in air.
4. The frequency of free vibration
a. 10 Hz b. 20 Hz c. 30 Hz d. 40 Hz
a. 114.5 Hz b. 214.5 Hz c. 314.5 Hz d. 414.5 Hz
11. The sound power level of a certain jet plane flying at a height of 1km is 160 dB (re10-12W). Find the maximum sound pressure level on the ground directly below the flight path assuming that the aircraft radiates sound equally in all directions.
a. 59.1 dB b. 69.1 dB c. 79.1 dB d. 89.1 dB
12. Speaker is a device that
a. Converts sound waves into current and voltage b. Converts current variations into sound waves c. Converts elctrical energy to mechanical energy d. Converts elctrical energy to electromagnetic energy
13. Which type of microphone operates on the principle that the electrical resistance of carbon granules varies as the pressure on the granules vary?
18. What is the sound energy per unit area at right angles to the propagation direction per unit time?
19. ________ is the unit of loudness level of a sound.
a. Dynamic b. Crystal c. Carbon d. Ribbon-type
a. Loudness b. Coherence c. Sound pressure d. Sound intensity
a. Sone b. Decibel c. Mel d. Phon
20. ____________ is the average rate of transmission of sound energy in a given direction through a cross-section area of 1 sqm at right angles to the direction.
14. Bass response is
a. Maximum high frequency response b. Emphasizing the high audio frequency c. Bypassing high audio frequencies d. Bypassing low audio frequencies
21. What is the unit of pitch?
15. Pure tone of sound used as standard on testing
a. 1 Hz b. 10 Hz c. 100 Hz d. 1000 Hz
a. Echo b. Reverberation c. Pure sound d. Intelligible sound
a. Dolby b. dBa c. dBx d. dBk
a. Phon b. Decibel c. Pascal d. Watts
23. Sound wave has two main characteristics characteristics which are
17. Noise reduction system used for film sound in movie.
a. Sone b. Phon c. Decibel d. Mel
22. A measure of the intensity of sound in comparison to another sound intensity.
16. ___________ is early reflection of sound.
a. Sound pressure b. Loudness c. Sound intensity d. Pressure variation
a. Highness and loudness b. Tone and loudness c. Pitch and loudness d. Rarefraction and compression
24. Which type of microphone operated by electromagnetic induction that generates an output signal voltage?
a. Carbon b. Dynamic c. Crystal d. Condenser
30. Speed that is faster than speed of sound.
25. The exciter lamp in the optical sound part of a film projector draws 5 A at 10 V. How much power in watts is this light consuming?
a. 10 watts b. 20 watts c. 40 watts d. 50 watts
26. Assume the speed of sound is 1,130 ft/s. What frequency has a wavelength of 1 foot, 1.5 inches?
a. 500 Hz b. 1000 Hz c. 1500 Hz d. 2000 Hz
a. 2 A b. 4 A c. 5 A d. 6 A
28. A church has an internal volume of 90.05 ft 3 (2550 m 3). When it contains customary sabine sof absorption (186 metric sabines), what will be its reverberation time in seconds.
a. 2.0 b. 2.2 c. 2.5 d. 3.0
29. If the RMs sound pressure is 5lb/ft 2, what is the sound presure level?
a. 7.6 dB b. 108 dB
a. 12.4 miles/sec b. 5000 ft/sec c. 186,000 ft/sec d. 3141 ft/sec
32. What is the sound power from a motor car whose SPL at a distance of 7.5 m is 87 dB assuming that it radiates sound unifomly?
a. 0.15 W b. 0.21 W c. 0.24 W d. 0.18 W
33. Crest-to-crest distance along the direction to wave travel.
a. Compression b. W avelength avelength c. Period d. Sound wave
34. Sound intensity level is _________.
a. Ultrasonic b. Supersonic c. Subsonic d. Transonic
31. Sound waves travel faster in water at a ______ speed.
27. The wire must bring 100 average watts to a 4 ohms loudspeaker must safely carry what rms current?
c. 88 dB d. 10 dB
a. 10 log I/I ref b. 10 log P/P ref c. 20 log I/I ref d. 30 log P/Pref
35. Sound pressure level is _________.
a. 20 log P/ P ref b. 30 log P/ P ref c. 10 log P/ P ref d. 20 log I/I ref
36. The most important specification of loudspeakers and microphones.
a. Frequency response b. Field strength c. Power density d. Gain
43. Which microphone will be damaged if exposed to high temperature above 52°C?
37. Lowest fequency produced by a musical instrument.
a. Midrange b. Harmonic c. Reflection d. Refraction
38. Tendency of a sound energy to spread.
44. A thin springy sheet of bakelite or metal that permits the voice coil in a dynamic loudspeaker to move back and forth salong the core of its magnet.
a. Diffraction b. Rarefraction c. Reflection d. Refraction
39. When waves bend away from straight lines of travel, it is called _________.
a. Reflection b. Diffraction c. Rarefraction d. Refraction
40. Required time for any sound to decay to 60 dB.
a. Echo time b. Delay time c. Reverberation time d. Transient time
41. The intensity needed to produce an audible sound varies with __________.
a. Frequency b. Noise c. Amplitude d. Tone
a. Subsonic b. Transonic c. Ultrasonic d. Stereo
a. 120 dB SPL b. 57.78 dB SPL c. 115.56 dB SPL d. 41.58 dB SPL
46. The reverberation time of a 184.2 cubic meters broadcast studio is 0.84 sec. Find the absorption effect of the materials used in metric sabines.
a. 35.3 b. 10.96 c. 379.8 d. 109.6
47. What is the microphone characteristic that results in a boost in bass frequencies for close microphone spacing?
42. Sound that vibrates too high for the human ear to hear (over 20 kHz).
a. Vibrator b. Diaphragm c. Hypex d. Spider
45. One hundred twenty µbars of pressure variation is equal to
a. Dynamic b. Crystal c. Ribbon d. Capacitor
a. Field effect b. P.A. effect c. Proximity effect d. Reverberation
48. What is the audio frequency range?
a. 20 kHz to 20 MHz b. 0 Hz to 20 kHz c. 300 Hz to 400 Hz d. 20 Hz to 20 kHz
49. What is the bass frequency range?
a. 2500 Hz to 5000 Hz b. 5000 Hz to 10 kHz c. 40 kHz to 160 kHz d. 10 Hz to 20 kHz
50. High frequency range of audio signals.
56. _________ is affected by the distance between the listener and the source of the sound and its intensity varies inversely with the square of its distance.
a. 2500 Hz to 5000 Hz b. 5000 Hz to 10 kHz c. 10 kHz to 20 kHz d. 20000 Hz to 30 kHz
51. What is the dB SPL of a voice paging in an office?
57. If the distance between the listener and the source of the sound is doubled, the intensity is reduced to
a. 90 b. 65 c. 55-60 d. 80-85
52. What is the dB SPL of an auditorium with contemporary music?
a. 80-95 b. 85-90 c. 95-100 d. 100-105
a. 90 b. 80-85 c. 85-90 d. 90-95
a. ½ b. 1/3 c. 2/3 d. 1/4
58. If the distance between the listener and the source of the sound is decreased to ½ tye original amount, the intensity of the sound would be
53. What is the church dB SPL with speech reinforcement only?
a. Volume b. Bass c. Treble d. Loudness
a. 2 times as great b. 3 times as great c. 4 times as great d. 5 times as great
59. At a sensation level of 40 dB, 1000 Hz tone is
a. 1000 mels b. 500 mels c. 2000 mels d. 100 mels
54. Intensity can also be called as
a. Volume b. Loudness c. Sharpness d. Strength
60. If the sound waves are converted to electrical waves by a microphone, what is the frequency of the electric current?
55. 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
a. 3 - 30 MHz b. 25 – 8000 Hz c. 4 – 40 Hz d. 30 – 3000 Hz
61. For a music lover concert “A” is 440 Hz.
If a musical note one octave higher were played, it would be _______ that frequency.
a. One – half b. One-fourth c. Double
d. Triple
62. In a 220 Hz, if a note was played one octave lower, it would be ______.
a. 22 Hz b. 27.5 Hz c. 440 Hz d. 110 Hz
69. The acoustics of most auditoria are very ________ ________ when the room is full compared compared to the empty condition.
63. Much of music is generally referred to in
a. Harmonics b. Good hearing c. Fidelity d. Octaves
64. _________ is an undesired change in wave form as the signal passes through a device.
a. Noise b. Vibration c. Distortion d. Harmonics
a. Equalizer b. Igniter c. Exciter d. Emulsifier
66. A class of signal processors.
a. b. c. d.
Amplifiers Equalizers Microprocessors Exciters
67. Half construction and internal finishes affect the final sound quality ________.
a. poorly b. mildly c. significantly d. badly
68. Positioning a loudspeaker near a wall can dramatically alter its frequency response in two distinct ways namely;
a. Expense and fidelity b. Complexity and ruggedness c. Longevity d. All of these
73. When the average absorption is greater than 0.2, __________ formula is used to compute the actual reverberation time.
a. Wired and body b. Ceramic and crystal c. Diaphragm and generating element d. Coil and magnet
72. The kinds of generating elements are __________. __________.
a. Electro-acoustic b. Microphone transducer c. Microphone d. Electric Microphone
71. All microphone have two basic components namely, ___________.
65. Distortion enhances intelligibly when an ________ ________ is added. added.
a. Different b. Similar c. Good d. Bad
70. A _________ converts acoustical energy.
a. Gump and dump b. Hump and notch c. Fade and gone d. Bad and worst
a. Sabine b. Stephen and Bate c. Norris-Eyring d. Notch
74. At room temperature, what is the velocity of sound in meters/seconds?
a. 348.03 cm/s b. 980 cm/s
c. 980 m/s d. 341.8 m/s
75. Calculate the velocity of sound in ft./sec. if the temperature is 149 0C?
81. For computation of ideal reverberation time, which formula is applicable?
a. 1530.03 ft/sec b. 1320 ft/sec c. 1357.03 ft/sec d. 1920.345 ft/sec
76. The wavelength of a sound of 20 kHz frequency is
82. The __________ of the sound is a subjective effect which is a function of the ear and brain.
a. 16.5 m b. 16.5 cm c. 16.5 mm d. 16.5 um
77. The radio of frequencies is termed
a. Octave b. Interval c. Harmonics d. Masking
78. What is the increase in sound pressure level in dB, if the pressure is doubled?
a. 2 dB b. 3 dB c. 6 dB d. 4 dB
a. Timbre b. Quality c. Frequency d. Pitch
80. An effect that occurs in the ear where a louder sound can reduce or even stop the nerve voltage generated by a weaker sound.
a. Piezoelectric effect b. Skin effect c. Lasing d. Masking
a. Loudness b. Coherence c. Sound stress d. Sound intensity
85. One octave above 600 Hz is
a. 601 Hz b. 800 Hz c. 1400 Hz d. 1200 Hz
86. A car horn outdoors produces a sound intensity level of 90 dB at 10 m away. At this distance, what is the sound power in watt?
a. Reverberation time b. Transit time c. Decaying time d. Response time
84. __________ is the sound energy per unit area at right angles of the propagation direction, per unit time.
a. Pitch b. Frequency c. Timbre d. Loudness
83. Define as the time taken from the intensity of sound energy in the room to drop to one millionth of its initial value.
79. A term which is subjected but dependent mainly on frequency and also affected by intensity,
a. Sabine b. Stephen and Bate c. Norris-Eyring d. Notch
a. 0.63 b. 1.26 c. 0.315 d. 0.56 x 10 -6
87. The unit of loudness level
a. Sone b. dB c. Mel d. Phon
94. Defined as the average rate of transmission of sound energy in a given direction through a cross-sectional area of 1 m2 at right angles to the direction.
88. Consist of a rapid succession of noticeable echoes.
a. Rarefaction b. Refraction c. Reflection d. Flutter echo
89. Laid the foundations of acoustic theory of buildings.
95. What is the sound pressure level (SPL) of a sound having a RMS pressure of 200 N/m2?
a. Charles H. Townes b. W.C Sabine c. A. Javin d. Stephen and Bate
90. An aural sensation by pressure variations in the air which are always produced by some source of vibrations.
a. Music b. Sound c. Disturbance d. Speech
91. Considered to be the threshold of hearing.
a. 10 W/cm b. 10-16 W/m2 c. 10-13 W/m2 d. 10-12 W/m2
2
a. 5.7 units b. 4.7 units c. 6.7 units d. 3.7 units
93. The number of vibration or pressure fluctuations per seconds.
a. Frequency b. Timbre c. Quality d. Pitch
a. sone b. pitch c. dB d. Mel
99. What is the increase in sound pressure level in dB, if the intensity is doubled?
a. 96.9 W/m 2 b. 97.9 W/m 2 c. 95.9 W/m 2 d. 94.9 W/m 2
98. The unit of pitch.
92. The average absorption for a person is
a. Threshold of feeling b. Threshold of pain c. Threshold of sensation d. Threshold of hearing
97. What is the intensity of the sound whose RMS pressure is 200 N/m 2?
-12
a. 150 dB b. 140 dB c. 170 dB d. 160 dB
96. The minimum sound intensity that can be heard is termed
a. Sound pressure b. Loudness c. Sound intensity d. Pressure variation
a. 2 dB b. 3 dB c. 4 dB d. 6 dB
100. The velocity of sound is considered to be constant at ________ for the purpose of acoustics.
a. 300 m/s b. 330 mm/s c. 330 µm/s d. 330 cm/s
101. What do you call the speed of sound in the study of acoustics?
107. a large speaker having a large diameter(15 cm and above)
a. Rhythm b. Tempo c. Pitch d. Frequency
102. The term that describes the highness or lowness of a sound in the study of acoustics is called a
a. Tempo b. Pitch c. Volume d. Bass
103. The method of measuring absorption coefficient of sound which considers all angles of incidence is called
a. Distance method b. Bounce back to back method c. Impedance method d. Reverberation chamber method
104. The tendency of a sound energy to spread
a. Rarefaction b. Reflection c. Refraction d. Diffraction
105. _____ is the advantage rate of transmission of sound energy in a given direction through a cross-sectional area of 1 sq m at right angles to the direction of propagation.
a. Sound pressure b. Sound intensity c. Pressure variation d. Loudness
a. Decibel
a. its temperature b. particle displacement c. softness d. source
112. _____ is the transmission of sound from one room to an adjacent room thru common walls, floors, or ceilings.
a. df/dp b. dE/dP c. dA/dP d. dP/dA
111. Which of the following is considered the most commonly used measurable components of sound?
106. The unit of pitch
a. Harmonic b. Fundamental c. Midrange d. 0 Hz
110. Sound intensity is given as
a. Frequency b. W avelength avelength c. Volume d. Pitch
109. The lowest frequency produced by an instrument
a. coaxial speaker b. woofer c. tweeter d. triaxial speaker
108. A method of expressing the amplitude of a complex non-periodic signal such as speech
b. Phon c. mel d. Sone
a. Reverberation b. Refraction c. Flanking transmission d. Reflection
113. The midrange frequency range of sound is from
a. 256 to 2048 Hz b. 2048 to 4096 Hz c. 512 to 2048 Hz d. 16 to 64 Hz
114. Designates the sensation of low or high in the sense of the bass and treble
120. A sound intensity that could cause painful sensation in a human ear
a. Frequency b. Intensity c. Pitch d. SPL
a. Around triple b. Around 15 times c. Around twice d. Around 5 times
a. Threshold of sense b. Threshold of pain c. Hearing threshold d. Sensation intensity
121. A car horn outdoors produces a sound intensity of 90 dB at 10 ft away. At this distance, what is the sound power in watt?
115. Speaker is a device that
a. Converts current variations into sound waves b. None of these c. Converts electrical energy to mechanical energy d. Converts sound waves into current and voltage
122. Noise reduction system for film sound in movie
116. One-hundred twenty microbars of pressure variation is equal to
a. 120 dBSPL b. 115.56 dBSPL c. 41.58 dBSPL d. 57.78 dBSPL
117. An instrument for recording waveforms of audio frequency
a. Oscilloscope b. Phonoscope c. Radioscope d. Audioscope
118. In the study of acoustics, the velocity of sound is dependent to one of the following
a. Temperature b. Loudness c. Source of sound d. Properties of the medium
119. How much bigger in storage capacity has digital video disk (DVD) have over the conventional compact disk (CD)?
a. Dynamic b. Crystal c. Carbon d. Ribbon-type
124. A unit of noisiness related to the perceived noise level
a. Dolby b. dBx c. dBa d. dBk
123. Which type of microphone operates on the principle that the electrical resistance of carbon granules varies as the pressure on the granules vary?
a. 12 W b. 0.12 W c. 0.012 W d. 1.2 W
a. Noy b. Sone c. dB d. Mel
125. Required time for and sound to decay to 60 dB
a. Echo time b. Delay time
c. Reverberation time d. Transient time
126. If the distance between the listener and the source of the sound is doubled, the intensity is reduced to
a. 1/2 b. 1/3 c. 2/3 d. 1/4
127. Positioning a loudspeaker near a wall can dramatically alter its frequency response in two distinct ways namely
132. A term which is subjective but independent mainly on frequency and also affected by intensity
a. Gump and dump b. Hump and notch c. Fade and gone d. Bad and worst
128. An effect that occurs in the ear where a louder sound can reduce or even stop the nerve voltage generated by a weaker sound
a. Piezoelectric effect b. Doppler effect c. Haas effect d. Masking
129. When the average absorption is greater than 0.2, ____ formula is used to compute the actual reverberation time.
a. Sabine b. Stephen and bate c. Norris-Eyring d. Notch
130. The minimum sound intensity that can be heard
a. Threshold of feeling b. Threshold of pain c. Threshold of sensation d. Threshold of hearing
131. The ____ of a sound is a subjective effect which is a function of the ear and brain.
a. Pitch b. Frequency
a. 13 Hz b. 11 Hz c. 15 Hz d. 14 Hz
137. 40 phons is equivalent to how many sones?
a. 249.19 m/s b. 331.45 m/s c. 357.73 m/s d. 358.77 m/s
136. What us the resonant frequency of a Helmholtz resonator whose volume is 2.5 cu m with neck radius of 8 cm?
a. 1000 mels b. 10000 mels c. 250 mels d. 800 mels
135. What is the velocity of sound in dry air for a temperature change of 45 degrees Celsius?
a. 18.3 mm b. 183mm c. 250 mels d. 1.86 mels
134. At a sensation level of 40 dB 1000 Hz tone is
a. Pitch b. Frequency c. Timbre d. Loudness
133. A sound 0f 18 kHz frequency has a wavelength of
c. Timbre d. Loudness
a. 0 sone b. 1 sone c. 0.5 sone d. 16 sones
138. 80 phons + 80 phons =
a. 83 phons b. 160 phons c. 90 phons d. 86 phons
145. How much power can a human voice possible produce
139. An early reflection of sound
a. Echo b. Reverberation c. Pure sound d. Jitter
a. Sound level meter b. Transducer c. Sound pressure meter d. Sound analyzer
a. Ear deafness b. Cortial deafness c. Tinnitus d. Presbycusis
a. 95-100 dB b. 40-50 dB c. 50-60 dB d. 70-80 dB
a. Variable capacitance b. Variable resistance c. Variable inductance d. Piezoelectric effect
a. Newtons b. Newtons per meter c. Newtons per meter squared
a. C-message weighting curve b. Psophometric curve c. Noise rating curve d. F1A weighting curves
150. Pure tone of sound used as standard on testing
144. Pressure is measured in term of Pascal, microbar or
a. Microphone b. Headphone c. Headset d. Speaker
149. An agreed set of empirical curves relating octave-band sound pressure level to the center frequency of the octave bands
143. What principle is used by a carbon type micro phone?
a. 300- 3000 Hz b. 20 Hz -20 kHz c. 3 – 3 kHz d. 40 -40 kHz
148. A device that converts sound pressure into electrical energy
142. What is the dBSPL of an auditorium with contemporary music?
a. Increase by 6 dB b. Increase by 3 dB c. Decrease by 6 dB d. Decrease by 3 dB
147. The frequency limits of audio frequency is
141. The term used for the deafness of higher frequencies due to old age
a. 100 milliwatts b. 1 watt c. 10 watts d. 1 milliwatt
146. What is the increase in sound pressure level if the pressure is doubled?
140. An instrument designed to measure a frequency weighted value of the sound pressure level
d. Pascal per meter squared
a. 1 kHz b. 300-3400 Hz c. 100 Hz d. 800 Hz
