Final answer:
The amplitude of a sound wave determines the psychological property of loudness. This is because louder sounds are created by sound waves with larger amplitudes, which produce greater pressure fluctuations in the medium. However, the perception of loudness is also influenced by the frequency of the sound and the listener's ear sensitivity.
Step-by-step explanation:
The amplitude of a sound wave corresponds to the psychological property of loudness. When you speak more loudly, the amplitude of the sound wave increases, making the sound louder to the listener. The term intensity level or decibel is also used to describe the loudness of sound, with higher decibels indicating a louder sound. For example, the loudness of a whistle would be characterized by both its high frequency and its high amplitude if it's described as a loud, shrill whistle. It's important to note, however, that the human ear has varying sensitivities to different frequencies, which also affects the perceived loudness.
Although amplitude is closely associated with loudness, some interaction between frequency and amplitude affects our perception of loudness. A sound at a very low frequency, such as 10 Hz, may be inaudible regardless of its amplitude, while a sound at 1000 Hz would be perceived as getting louder as the amplitude increases. Additionally, the speed of the wave is not directly related to loudness but rather to the medium through which the sound is traveling.