Final answer:
In a sound wave, the density of the medium varies with every cycle. The speed of sound is determined by the properties of the medium, and the amplitude of a sound wave is associated with its loudness.
Step-by-step explanation:
When considering a sound wave, the parameter of the medium that varies with every cycle is the density. In each cycle of a sound wave, areas of compression and rarefaction occur, causing the density of the medium to increase and decrease respectively. These variations in density facilitate the propagation of the sound wave through the medium.
The speed of sound depends on the properties of the medium it is traveling through, rather than the frequency or wavelength of the sound wave itself. Thus, factors such as temperature, phase of the medium (solid, liquid, or gas), and the medium's elasticity affect how fast sound travels through it.
The amplitude of a sound wave is related to the perceived loudness or volume of the sound. A wave with greater amplitude has more energy and is perceived as louder, while a wave with lower amplitude is perceived as softer.