Gibilisco - Acoustics, Audio, And High Fidelity
- 1.A young person can hear sounds at frequencies as high as approximately which of thefollowing?
- A.
20 Hz
- B.
20 kHz
- C.
20 MHz
- D.
20 GHz
- 2.Electromagnetic interference to a hi-fi amplifier can occur in the presence of
- A.
A nearby radio broadcast station.
- B.
Improperly designed receiving antennas.
- C.
Excessive utility voltage.
- D.
Improper balance between the left and right channels.
- 3.The midrange audio frequencies
- A.
Are exactly halfway between the lowest and highest audible frequencies.
- B.
Represent sounds whose volume levels are not too loud or too soft.
- C.
Are above the treble range but below the bass range.
- D.
None of the above are true.
- 4.In the acoustical design of a room intended for a home audio system,
- A.
The use of small speakers can minimize distortion.
- B.
Reflection of sound waves from walls should be minimized.
- C.
The walls should all intersect at perfect 90° angles.
- D.
Wooden furniture, without upholstery, should be used.
- 5.A change of +10 dB in an audio signal represents
- A.
A doubling of acoustic power.
- B.
A threefold increase in acoustic power.
- C.
A tenfold increase in acoustic power.
- D.
No change in acoustic power, but a change in frequency.
- 6.What is the frequency of an acoustic disturbance whose wavelength is 120 mm in air?
- A.
279 Hz
- B.
2.79 kHz
- C.
35.8 Hz
- D.
358 Hz
- 7.What is the frequency of a sound wave that propagates at a speed of 1100 ft/s?
- A.
33.5 Hz
- B.
335 Hz
- C.
3.35 kHz
- D.
Forget it! The frequency of a sound wave is independent of the propagation speed.
- 8.The relative phase of two acoustic waves from the same source at the same time, one wavedirect and one wave reflected from a wall, can affect
- A.
The positions of antinodes and nodes.
- B.
The perceived frequency.
- C.
The positions of antinodes and nodes, and the perceived frequency.
- D.
Neither the positions of the antinodes and nodes, nor the perceived frequency.
- 9.In an acoustic sine wave,
- A.
The frequency and phase are identical.
- B.
The sound power is inversely proportional to the frequency.
- C.
The sound power is directly proportional to the frequency.
- D.
All of the sound power is concentrated at a single frequency.
- 10.Vinyl disks are
- A.
Susceptible to physical damage.
- B.
Useful primarily in high-power sound systems.
- C.
Digital media.
- D.
Preferred for off-the-air sound recording.
- 11.If an amplifier introduces severe distortion in the waveforms of input signals, then thatamplifier is
- A.
Not delivering enough power.
- B.
Operating at the wrong frequency.
- C.
Operating in a nonlinear fashion.
- D.
Being underdriven.
- 12.Suppose a 10-W amplifier is used with speakers designed for a 100-W amplifier. Which ofthe following statements is true?
- A.
The speakers are capable of handling the amplifier output.
- B.
The amplifier might be damaged by the speakers.
- C.
Electromagnetic interference is more likely to occur than would be the case if the speakers were designed for a 10-W amplifier.
- D.
The speakers are likely to produce excessive distortion.
- 13.Which of the following frequencies cannot be received by an AM/FM tuner?
- A.
830 kHz
- B.
95.7 kHz
- C.
90.1 MHz
- D.
107.3 MHz
- 14.Which of the following statements about woofers is true?
- A.
They are especially useful for reproducing the sounds of barking dogs.
- B.
They are designed to handle short, intense bursts of sound.
- C.
They should not be used with graphic equalizers.
- D.
They are specifically designed to reproduce low-frequency sounds.
- 15.Suppose you have an amateur radio station and its transmitter causes EMI to your hi-fisystem. Which of the following would almost certainly not help?
- A.
Build a new transmitter that works on the same frequencies with the same power output as your existing transmitter.
- B.
Reduce the transmitter output power.
- C.
Install shielded speaker wires in the hi-fi system, and be sure the system is well grounded.
- D.
Move the amateur radio transmitting antenna to a location farther away from the hi-fi system.
- 16.In an analog audio tape recorder/player, the recording head
- A.
Converts sound waves to radio signals.
- B.
Converts sound waves to fluctuating electric current.
- C.
Converts AF current to a fluctuating magnetic field.
- D.
Converts dc to AF current.
- 17.A rack-mounted hi-fi system
- A.
Can save floor space.
- B.
Is more susceptible to EMI than a compact system.
- C.
Is cheaper than a compact system.
- D.
Is designed especially for use with vinyl disks and turntables.
- 18.An audio mixer
- A.
Cannot match impedances among interconnected components.
- B.
Cannot increase the audio output of an amplifier.
- C.
Eliminates EMI problems in all but the worst cases.
- D.
Allows a microphone to be used as a speaker.
- 19.Which of the following devices or circuits ordinarily employs D/A conversion?
- A.
A portable CD player
- B.
A turntable for use with vinyl disks
- C.
An analog audio tape recording/playback system
- D.
An RC tone control
- 20.Which of the following is an advantage of digital audio over analog audio?
- A.
Digital media can be used to record and play back audio at higher frequencies than can analog media.
- B.
Multigeneration copies of digital audio programs can be made without degradation in fidelity, but this is not true of analog audio programs.
- C.
Digital audio is compatible with vinyl disks and old-fashioned reel-to-reel and cassette tape, but analog audio is not.
- D.
There are no genuine advantages of digital audio over analog audio. In fact, analog audio is superior to digital audio in every respect.
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