The amplitude of a sound wave determines its loudness or volume. In general, a loud sound corresponds to a larger amplitude, while a soft sound corresponds to a smaller amplitude. The amplitude of a sound wave represents the magnitude or height of its oscillations.
Visually, if we were to represent a loud sound wave on a graph where the vertical axis represents the displacement or pressure variation of the sound wave, a loud sound would be depicted with a larger vertical extent. This means that the wave would have larger peaks and troughs, indicating a greater difference between the maximum and minimum values of the pressure or displacement.
To illustrate this, imagine a graph with time on the horizontal axis and the amplitude (pressure or displacement) on the vertical axis. A loud sound wave would appear as a wave with high peaks and deep troughs. The wave would exhibit more pronounced oscillations and have a greater vertical span compared to a soft sound wave on the same graph.
It's important to note that the amplitude of a sound wave is typically represented on a logarithmic scale, such as decibels (dB), to account for the wide range of sound intensities that humans can perceive. The decibel scale is logarithmic because our perception of loudness follows a logarithmic relationship with the physical amplitude of the sound wave. This means that each increase of about 10 dB corresponds to a perceived doubling in loudness.