Final answer:
The frequency spectrum analysis of a pressure-time record involves identifying the periodic components of a sound wave and reveals how pressure varies with time, detailing the composition of frequencies and their amplitudes.
Step-by-step explanation:
In addressing the question of determining the frequency spectrum from a pressure-time record, such as the one depicted in the figures provided, it involves identifying the periodic components and distributing them across different frequencies. The frequency spectrum analysis is particularly useful in characterizing attributes of sound waves, such as their intensity and shifts due to the Doppler effect. The spectrum indicates how pressure varies over time by revealing the collection of frequencies that make up the wave and their respective amplitudes.
The pressure variations seen in graphs like Figure 17.5 and Figure 17.3(a) can be modeled as sinusoidal functions, indicative of the compressions and rarefactions of sound waves. From these graphs, one can extract the period and frequency—crucial parameters for describing sound. The frequency itself is associated with the sound's intensity, where higher frequencies correspond to more significant pressure extremes and higher sound intensity.
Understanding a sound wave's frequency is not only crucial for analyzing its physical properties but also for exploring phenomena such as the Doppler effect, where the relative motion between a source and an observer affects the perceived frequency. This analysis, therefore, contributes to the fundamental understanding of waves, as detailed in sections of physics textbooks covering sound and wave behavior.