What device can be used to visualize changes in sound waves when observing the Doppler Effect?

The device that can be used to visualize changes in sound waves when observing the Doppler Effect is an oscilloscope. An oscilloscope displays electrical signals as waveforms and allows users to see the variations in amplitude and frequency of the sound waves.

In the context of the Doppler Effect, when a sound source moves relative to an observer, the frequency of the sound waves changes, leading to a perceived shift in pitch. An oscilloscope can graphically represent these changes by showing how the frequency and amplitude of the sound waves change over time. As the sound source approaches, the waves compress, resulting in higher frequency waves, which can be observed as changes in the waveform on the oscilloscope. Conversely, as the source moves away, the waves stretch, lowering the frequency and changing the waveform accordingly.

Other devices mentioned do not directly relate to visualizing sound waves and their changes. An electroscope is primarily used for detecting electric charge, while diffraction gratings are used to analyze light waves rather than sound waves. The term "ground" does not refer to a device for visualizing waveforms. Thus, the oscilloscope stands out as the appropriate tool for studying the Doppler Effect in sound waves.