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Practice Listening: Multiple Choice, Multiple Answers ID: #40983 Long Compact discs

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Transcript:

Compact discs, often called CD's, are round, flat plastic discs on which information is stored as a pattern of tiny pits and flat spaces on an audio CD's, information about recorded sound is contained in the pits and spaces. When the sound is recorded, a microphone translates the sound waves into electric signals. These signals are then divided into segments by electric circuit. For each second of recorded sound, there are 44,100 segments. The strength of each segment, which varies according to the original sound, is translated into a digital or numeric code. In this code, each sound segment is expressed as a series of electric pulses representing ones and zeros. During disk manufacturing, a laser uses the digital code as a pattern to guide the cutting of a spiral track of microscopic pits into the surface of one side of a blank disc. During the mass production of CDs, this pattern of pits is pressed on plastic discs. The discs are then covered with a thin reflective metal and given a clear plastic coating for protection. During playback in a CD player, a laser reads the pits. As the CD spins inside the player, a laser beam shines on the underside of the disk, which contains the pit spiral. The light is reflected by the disc's metal coating. The intensity of the reflection changes as the beam enters and leaves the pits. The reflected light strikes a device that translates these differences into an electric signal. This signal is a copy of the electric signal that was produced during the recording of the original sound. The CD player uses the electric signal to reproduce the original sound through loudspeakers or headphones.

Which of the following statements are true about the process of recording and playing back sound on a compact disc (CD)?

* Click on the correct answers

The original sound is directly etched onto the CD as a series of pits without digital conversion. A laser reads the pits on the CD during playback, translating them into an electric signal. Sound is recorded by dividing electric signals into 44,100 segments per second. The pits and spaces on a CD represent different musical notes. The digital code for sound is translated into electric pulses representing binary numbers. Sound segments are translated into a digital code using a microphone alone.

Result:

A.I. Explanation:

Option 1: "The original sound is directly etched onto the CD as a series of pits without digital conversion."
Explanation: This option is incorrect because the text states that the original sound is first converted into electric signals and then into a digital code before being represented as pits on the CD. The process involves digital conversion, which this option overlooks.
Option 2: "A laser reads the pits on the CD during playback, translating them into an electric signal."
Explanation: This option is correct as the text explicitly mentions that during playback, a laser reads the pits on the CD and translates the reflected light differences into an electric signal, which is a direct representation of the original sound.
Option 3: "Sound is recorded by dividing electric signals into 44,100 segments per second."
Explanation: This option is correct because the text states that for each second of recorded sound, there are 44,100 segments, indicating that the sound is indeed recorded by dividing the electric signals into these segments.
Option 4: "The pits and spaces on a CD represent different musical notes."
Explanation: This option is incorrect as the text does not mention that pits and spaces represent musical notes. Instead, it explains that they represent the recorded sound information in a digital format, not specific musical notes.
Option 5: "The digital code for sound is translated into electric pulses representing binary numbers."
Explanation: This option is correct because the text describes how the strength of each sound segment is translated into a digital code expressed as electric pulses representing ones and zeros, which are indeed binary numbers.
Option 6: "Sound segments are translated into a digital code using a microphone alone."
Explanation: This option is incorrect because the text indicates that while a microphone translates sound waves into electric signals, the process of creating a digital code involves additional steps, including dividing these signals into segments and translating them into a digital format.

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