ACOUSTICS FUNDAMENTALS
1. You are at a party and talking with a group of people. They all produce levels of the same magnitude at your position. The combined level w four talks at once is 76 dB. If another group o off people join the conversation with an individual level of 68 dB each and produce a total level of 82.12 dB together with the 1 st group, determine how many people join the c onversation A. 15
B. 5
C. 30
D. 20
2. During a fireworks show a rocket explodes. To a listener who is 640 m away, the sound has an 2
intensity of 0.10 mW/m . What is the intensity for a listener who is 160 m away? 2
2
A. 5.6 mW/ m B. 6.6 mW/ m 2
C. 1.6 mW/ m
2
D. 3.6 mW/ m
3. The sound power level of a jet plane flying at a height of 1 km is 160 dB (ref 10 exponent -12 W). What is the maximum sound pressure level on the ground directly below the plane 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
4. A periodic wave passes an observer, who records that there is a time of .5 s between crests. A. the frequency is 0.5 Hz
B. the speed is 0.5 m/s
C. the wavelength is 0.5 m
D. the period is 0.5 s.
5. For a harmonic wave of a certain type in a given medium, doubling the frequency has the effect of A. halving the speed
B. halving the wavelength
C. doubling the amplitude
D. doubling the period
6. A dB-meter is placed in front of an audio system reads 62 dB. The volume is turned up and the meter now reads 72 dB. Evidently, t he sound got A. twice as loud
B. half as loud
C. 20x louder
D. 10x louder
7. __________ is the transmission of sound from one room to an adjacent room through common wall, floors or ceilings. A. Reflection
B. Flanking transmission
C. Refraction
D. Reverberation
8. ________ is the average rate of transmission of sound energy in a given direction through a cross sectional area of is square meter at right angle to the direction. A. Pressure variation
B. Loudness
C. Sound pressure
D. Sound intensity
9. A speaker cabinet has an internal volume of 84,950 square cm. It has a port area on the baffle of 3,230 square cm and a baffle thickness of 19 mm. What is the Helmholtz resonance in hertz of this speaker enclosure? A. 245 Hz
B. 250 Hz
C. 260 Hz
D. 265 Hz
10. Two audio systems at a demonstration are blasting away, with one putting out 10x the acoustic power of the other. What is the difference in their sound levels? A. 10 dB
B. 5 dB
C. 13 dB
D. 16 dB 2
11. A small but noisy printer produces an acoustic intensity of 560 µW/m at a point 5 m away. Approximately what value will a dB-meter read 20 m from the printer? A. 85 dB
B. 65 dB
C. 75 dB
D. 95 dB
12. The midrange frequency range of sound is from A. 16 to 64 Hz
B. 256 to 2048 Hz
C. 2048 to 4096 Hz
D. 512 to 2048 Hz
13. One violin playing produces a sound level of 68 dB at your ears. If a second violin plays, producing the same sound level at your ear, what is the sound level from both violins playing? A. 75 dB
B. 71 dB
C. 77 dB
D. 79 dB
14. An instrument for recording waveform of audio frequency. A. Audioscope B. Radioscope C. Phonoscope D. Oscilloscope
15. What is the increase in sound pressure level in dB, if the pressure is double? A. 2 dB B. 3 dB C. 6 dB D. 4 dB 16. One hundred twenty Oars of pressure variation is equal to _______. A. 120 dBSPL
B. 41.58 dBSPL
C. 57.58 dBSPL D. 115.56 dBSPL 17. The reverberation time of a 184.2 cubic meters broadcast studio is 0.84 s. Find the absorption effect of the materials used in metric sabines. A. 35.3
B. 379.8
C. 109.6
D. 10.96
18. A 40-W, 430 mA fluorescent tube produces 3200 lumens. What is the illumination on the floor of a 10-ft2 room assuming 40% overall efficiency and uniform illumination? A. 17.7 lux
B. 37.7 lux
C. 137.7 lux
D. 13.7 lux
19. What is the increase in sound pressure level in dB, if the intensity is doubled? A. 2 dB B. 3 dB C. 6 dB D. 4 dB 20. If the distance between the listener and the source of the sound is doubled, the intensity is reduced to A. 1/2 B. 1/8 C. 1/16 D. 1/4 2
21. What is the sound pressure level of a sound having an RMS pressure of 200 N/m ? A. 140 dB
B. 170 dB
C. 150 dB
D. 160 dB 2
22. What is the intensity of sound whose RMS pressure is 200 N/m ? 2
B. 95.8 W/m
2
D. 94.8 W/m
A. 96.8 W/m C. 97.8 W/m
2
2
23. Determine the total PWL of 3 motors with a radiated acoustic power of 22mW, 43mW, and 79mW respectively and calculate the SPL 15 m from an observer. A. 116.7 dBPWL, 83.87 dBSPL
B. 83.87 dBPWL, 116.7 dBSPL
C. 56.53 dBPWL, 111.6 dBSPL
D. 111.6 dBPWL, 56.53 dBSPL
24. What is the individual PWL of 7 air-conditioned with a total PWL of 116 dB? A. 127. 55 dB
B. 107. 55 dB
C. 97. 55 dB
D. 117. 55 dB
25. Sound intensity is given as. A. df/dP
B. dP/dA
C. dE/dP
D. dA/dP
26. Designates the sensation of low or high in the sense of the base and treble. A. Pitch
B. SPL
C. Frequency
D. Intensity 3
27. A church has an interval volume of 90.05 ft3 (2,550 m ). When it contains 2,000 customary sabins of absorption (186 metric sabins), what will be its reverberation t ime in seconds. A. 3.0
B. 2.5
C. 2.0
D. 2.2
28. reduction system used for film sound in movie. A. dolby
B. dBm
C. dBa
D. dBx
TELEVISION FUNDAMENTALS
29. Calculate the equivalent IRE unit of a video signal with a luminance of 72%. A. 4.1 IRE units B. 53.8 IRE units
C. 74.1 IRE units D. 66.4 IRE units 30. Determine the possible increase in vertical details if the video frequency bandwidth were allowed up to 5 MHz. (assume 70% Kell factor) A. 408 pixels
B. 420 pixels
C. 442 pixels
D. 480 pixels
31. Calculate the vertical resolution if the video signal bandwidth were reduced from 4 to 3.5 MHz assuming that the horizontal resolution was not to change. A. 307 lines
B. 337 lines
C. 327 lines
D. 317 lines
32. One-half line spacing between the start positions for scanning even and odd fields produces A. linear scanning
B. exact interlacing
C. fishtailing
D. line pairing
33. What is the exact picture carrier frequency for channel 2 offset by -10 kHz? A. 55.24 MHz
B. 55.34 MHz
C. 51.25 MHz
D. 55.75 MHz
34. Calculate the sound and picture carrier frequency for channel 10 after frequency translation to the IF. A. P=45.75 MHz, S=41.25 MHz B. P=45.25 MHz, S=41.75 MHz C. P=41.75 MHz, S=45.25 MHz D. P=41.25 MHz, S=45.75 MHz 35. Color mixture is close to blue. A. Y
B. G-Y
C. R-Y
D. B-Y
36. Calculate the percentage of time occupied by vertical blanking. A. 0.8% B. 8% C. 28% D. 18%
37. Calculate the total number of picture elements (pixels) in an NTSC frame if the video BW is 4.2 MHz. (Assume 0.7 Kell factor, 4/3 aspect ratio, and 10 µs retrace time) A. 151,761 pixels
B. 211,161 pixels
C. 181,661 pixels
D. 192,416 pixels
38. Weak emission from one cathode in a tricolor picture tube causes _________, _________, and ________ in the raster and picture. A.
a stronger picture, a long warm up time, color balance
B.
a weak picture, a long warm up time, and color imbalance
C.
a stronger picture, a short warm up time, and color imbalance
D.
a weak picture, a short warm up time, and color balance
39. _______ correction signals can be inserted in series with the V and H coils of the deflection yoke, to straighten the edges of the raster. A. Gamma
B. Pincushion
C. Comb
D. Contrast
40. Calculate the minimum viewing distance for an HDTV system assume that a projector screen with a diagonal dimension of 1.4 m and an aspect ratio of 16:9 is used with 1125 vertical lines (90 suppressed). A. 2.7 m
B. 2.23 m
C. 3.61 m
D. 1.8 m
41. Greater p-p amplitude of the 3.58-MHz chrominance signal indicates more A. saturation
B. yellow
C. white
D. hue
42. With a 2-MHz video signal modulating the picture carrier signal for channel 4, which of the following frequencies are transmitted? A.
67.25-MHz carrier frequency with 65.25-MHz upper side fre quencies
B.
66-MHz carrier frequency and 68-MHz upper side frequency
C.
67.25-MHz carrier frequency and 69.25-MHz upper side frequency
D.
71.75-MHZ carrier frequency with 69- and 73-MHz side frequency
43. Compared to a monochrome CRT, the accelerating voltage on a color CRT is: A.
about the same
B.
much higher
C.
much lower
D.
color CRTs use magnetic acceleration
44. Interfaced scanning eliminates _______ because of the _______ blanking rate, while maintaining the ________.rate for complete picture frames. A.
flicker, 60-Hz vertical, 30-Hz
B.
flicker, 30-Hz vertical, 15,750-Hz
C.
ghost, 60-Hz vertical, 15,750-Hz
D.
ghost, 15,750-Hz vertical, 30-Hz
45. Determine the ghost width on a TV screen 15 in wide when a reflected wave results from an object 1/2 mi "behind" a receiver. A. 151 in
B. 15.1 in
C. 1.51 in
D. 0.151 in
46. A horizontal resolution of 300 lines corresponds to ______ pixels of picture pixels of picture information. A. 210 B. 150 C. 400 D. 200 47. In the CED system, the disk capacitance varies with the A. disk size
B. wavelength of the scanning light
C. speed of rotation
D. pit depth
48. The modulated picture carrier wave includes the com posite video signal as the A.
upper envelope without the lower envelope
B.
lower sideband without the upper sideband
C.
average carrier level
D.
symmetric envelope of amplitude variations
49. Calculate the magnitude chrominance for color yellow. A. 0.45 B. 0.69 C. 0.65 D. 0.21 50. The average voltage value of the 3.58-MHz modulated chrominance signal is A. the saturation of the color
B. zero for most colors
C. the brightness of the color
D. close to black for yellow
51. If the 3.58-MHz C amplifier in the receiver does not operate, the result will be A. no color
B. too much blue
C. too much yellow
D. no red
52. Light flux for cameras usually is measured in A. Tesla
B. footcandles
C. luminous intensity
D. lux
53. A _______ is a special camera tube with a test pattern printed on the image plate. A. plumbicon
B. iconoscope
C. monoscope D. vidicon 54. Calculate the exact color subcarrier frequency if this value is made to be the 455th harmonic of half of the horizontal frequency. A. 3.58 MHz
B. 4.2 MHz
C. 3.579545 MHz
D. 4.5 MHz
55. _________ is an exponential value that specifies how white light values are expanded or compressed, and this affects the contrast ratio. A. Alpha
B. Gamma
C. Beta
D. Sigma
56. What is the exact frequency separation between sound carrier and color subcarrier?
A. 0.92 MHz
B. 0.920455 MHz
C. 0.920945 MHz
D. 0.920495 MHz
57. The complementary color for blue, red and green are ________, ________, and _________ respectively. A. cyan, yellow, magenta
B. magenta, yellow, cyan
C. cyan, magenta, yellow
D. yellow, cyan, magenta
58. Converting hue and saturation in the C signal to R, G, and B primary color video signals for the tricolor picture tube. A. compandoring
B. decoding
C. multiplexing
D. encoding
59. How many flyback lines are produced during vertical retrace for each field and each frame when the retrace time is 0.03V? A. 8 and 16
B. 16 and 18
C. 18 and 16
D. 16 and 8
60. Which signal has color information for 1.3-MHz bandwidth? A. R-Y B. Y C. I
D. B-Y
61. Determine the number of horizontal details for a 4 MHz video bandwidth. A. 416 picture elements
B. 446 picture elements
C. 426 picture elements
D. 486 picture elements
62. Pictures frames are repeated at the rate of ________ per second. A. 60
B. 50
C. 30
D. 25
63. In all standard television broadcast channels, the difference between the picture and sound carrier frequencies is A. 0.25 MHz
B. 1.25 MHz
C. 4.5 MHz
D. 6 MHz
64. Which control varies the phase angle of the demodulated color video signal? A. picture
B. drive
C. tint
D. color level
65. Picture tubes have two black conductive coating made of _________. A. Tellurium
B. Phospor
C. Aquadag
D. Arsenic
66. ________ adjustments cause the three electron beams to excite the correct colors on the screen. A. Comb
B. Color
C. Convergence
D. Gamma
67. What are the lower and upper side frequencies for 200-kHz color video modulation in the 3.58MHz bandpass amplifier? A. 3.28 and 6.78 MHz
B. 3.38 and 3.78 MHz
C. 3.28 and 5.48 MHz
D. 3.38 and 6.28 MHz
68. In the frame for which interlaced scanning is used, alternate lines are skipped during vertical scanning frequency because A. the frame has a 4:3 aspect ratio B. the vertical scanning frequency is doubled from 30 to 60 Hz C. the horizontal scanning is slower than vertical scanning D. the trace is slower than the retrace 69. Which of the following frequencies is wrong? A.
15,750 Hz for horizontal sync and scanning
B.
31,500 for the vertical scanning frequency
C.
31,500 for equalizing pulses and serrations in the vertical sync pulse
D.
60 Hz for vertical sync and scanning
70. For a 4-MHz video signal, the number of horizontal details in a line is ____________. A. 525 B. 331 C. 426 D. 645
71. The circuit that combines C signal and Y luminance signal. A. color stacker
B. Colorplexer
C. Combiner
D. comb filter
72. Black on the picture tube screen results from ________ beam current. A. negative
B. maximum
C. zero
D. positive
73. Assume a facsimile reproduction with specifications of 200 lines/frame, progressive scanning, and 5 frame/sec. Calculate the visible trace time for one line with 4% blanking. A. 9.6 µs
B. 960 µs
C. 0.96 µs
D. 90 µs
74. Determine the maximum luminance level for magenta. A. 87% B. 48% C. 41% D. 34% 75. Picture tubes use _______ focusing. A. electromagnetic
B. electrostatic
C. electroacoustic
D. magnetostatic
76. If the phase chrominance for color yellow is 167°, what is the phase chrominance for c olor blue? A. 3.47° B. 34.7° C. 37°
D. 347°
77. Calculate the video frequency response corresponding to the horizontal resolution of 320 lines. A. 4.75 MHz
B. 4 MHz
C. 4.5 MHz
D. 4.2 MHz
78. Luminance is measured in: A. foot-candles
B. lumens
C. IRE units
D. NTSC units
79. What proportion of the maximum transmitter power is used to transmit a black setup level?
A. 73.4%
B. 22.2%
C. 61.1%
D. 45.6%
80. What is the hue of a color 90° leading sync burst phase? A. blue
B. cyan
C. orange
D. yellow
81. The back porch is __________ longer than the front porch A. 3x
C. 2x
B. 4x
D. 8x
82. Calculate the total percentage of the signal time occupied by vertical, horizontal, and active video respectively. A. 21%, 42%, 88%
B. 8%, 15.7%, 77.6%
C. 12.75%, 100%, 77.6%
D. 16%, 21%, 88%
83. ______ deflection is used for picture tubes. A. Static
B. Magnetic
C. Electrostatic D. Magnetostatic 84. Under ideal conditions, the eye can resolve two details subtending 0.5 minutes of ar c. Suppose a monitor screen 30 cm wide is located 1.5 m from a viewer. What video bandwidth would be required to separate horizontal details in the center of the screen by 0.5 minutes of arc assuming NTSC video? A. 4.5 MHz
B. 1.5 MHz
C. 5.1 MHz
D. 12.9 MHz
85. The sync pulse level corresponds to a luminance of: A. white
B. black
C. whiter than white
D. blacker than black
86. In a color TV receiver, Y I Q refers to: A.
luminance signal, in-phase color component, quadrature phase color component
B.
composite color signal, [n-phase color component, quadrature phase color component
C.
composite video signal, in-phase video component, quadrature video color component
D.
a method of demodulating stereo sound
87. The modulation used for the video signal in a standard NTSC color TV receiver is: A. SSB
B. vestigial sideband AM
C. suppressed-carrier AM
D. FM
88. ________convergence adjustments are made by permanent magnets. A. Static
B. Active
C. Dynamic
D. Moving
89. The number of fields is ______ per frame. A. 2
C. 60
B. 30
D. 525
90. Video signal amplitude dete rmines the picture quality called _________. A. contrast
B. resolution
C. color saturation
D. brightness
BROADCASTING STANDARDS
91. One of the following is a possible cause of an abrupt frequency variation in a self exited transmitter oscillator circuits resulting to poor frequency stability to hold a constant frequency oscillation. A.
Heating of capacitor in the oscillator
B.
Heating and expansion of oscillator coil
C.
DC and RF heating of resistors which change in values
D.
Loose connections in the oscillator, amplifier, or antenna circuits
92. Determine the effective radiated power of 20 kW TV broadcast transmitter whose antenna has a field gain of 2. A. 40,000 watts
B. 80 kW
C. 40 kW
D. 8,000 watts
93. The actual vertical resolution of broadcast TV with reference to the number of horizontal lines. A. 428 lines
B. 485 lines
C. 525 lines
D. 339 lines
94. One of the following is the referred to as the number of scanning lines per frame for NTSC standard. A. 625 lines
B. 325 lines
C. 425 lines
D. 525 lines
95. One of the following is a high powered RF ac basic transmitter that has two or more stages, the oscillator stage which determines the frequency of operation and RF amplifier stage or stages that develop the high power output. The purpose of which is to develop a good frequency stability. A. Hartley
B. Alexanderson
C. MOPA
D. Goldsmith
96. The final amplifier of either FM or AM t ransmitter operates as A. class C
B. class A
C. class B
D. class D
97. The allowable deviation ratio of commercial FM broadcast. A. 15
B. 5
C. 25
D. 75
98. An antenna that can only receive a television signal. A. TVRO
B. Reference antenna
C. Isotropic antenna
D. Yagi antenna
99. With which emission type is the capture-effect more pronounced? A. CW B. FM C. SSB D. AM 100.
What is emission F3F?
A. Facsimile
B. Television
C. Modulated CW
D. RTTY
