The graph of a sound wave is often depicted as a wave because it represents the changes in air pressure over time caused by the movement of vibrating objects or sources. While sound itself travels in a straight line as longitudinal waves, the graph of a sound wave displays its amplitude (intensity) and frequency (pitch) variations over time.
Sound waves are characterized by their amplitude and frequency. The amplitude corresponds to the magnitude of the pressure variations, which determines the loudness or intensity of the sound. The frequency represents the number of complete oscillations or cycles the sound wave completes per unit of time, determining the pitch or perceived frequency of the sound.
When a sound wave is graphed, the vertical axis typically represents the amplitude or pressure, while the horizontal axis represents time. As the vibrating object or sound source moves back and forth, it creates areas of compression and rarefaction in the surrounding medium (such as air). These variations in pressure are graphed as waves, with the peaks and troughs representing areas of high and low pressure, respectively.
The graphed representation of sound waves as waves helps visualize their properties and allows for analysis and comparison of different sound signals. It's important to note that the graph of a sound wave is a representation of the physical properties of the sound wave and not the actual physical motion of the sound wave itself, which travels in a straight line from the source.