Dale - Computer Science Illuminated 98

Dale - Computer Science Illuminated 98 - To reproduce the...

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3.4 Representing Audio Information 71 this peak value is lost Figure 3.8 Sampling an audio signal Figure 3.7 A sound wave vibrates our eardrums way to accomplish this is to actually digitize the analog representation of the sound. That is, take the electric signal that represents the sound wave and represent it as a series of discrete numeric values. An analog signal varies in voltage continuously. To digitize the signal we periodically measure the voltage of the signal and record the appropriate numeric value. This process is called sampling . Instead of a continuous signal, we end up with a series of numbers representing distinct voltage levels.
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Unformatted text preview: To reproduce the sound, the stored voltage values are used to create a new continuous electronic signal. The assumption is that the voltage levels in the original signal changed evenly between one stored voltage value and the next. If enough samples are taken in a short period of time, that assumption is reasonable. But certainly the process of sampling can lose information, as shown in Figure 3.8. In general, a sampling rate of around 40,000 times per second is enough to create a reasonable sound reproduction. If the sampling rate is much...
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