The amplitude of a sound wave directly determines its loudness or volume.
The Core Relationship: Amplitude and Loudness
The most fundamental aspect determined by a sound wave's amplitude is how loud we perceive the sound to be.
- Direct Correlation: A larger amplitude signifies a more intense vibration in the medium (like air) carrying the sound. This increased intensity translates directly into a louder sound.
- Conversely, a smaller amplitude indicates less intense vibration, resulting in a softer sound.
Think of it like ripples in water: a larger ripple carries more energy and makes a bigger splash, just as a sound wave with larger amplitude carries more energy and sounds louder.
As noted in the reference, "A larger amplitude means a louder sound, and a smaller amplitude means a softer sound."
Example from the Reference
The provided reference gives a specific example: "In Figure 10.2 sound C is louder than sound B." This comparison illustrates the principle that a sound with a greater amplitude (Sound C in this case) will be perceived as louder than a sound with a smaller amplitude (Sound B).
How Amplitude is Set
While amplitude determines loudness, how the amplitude is initially created is also key. According to the reference, "The vibration of a source sets the amplitude of a wave."
- Source Intensity: The force or energy put into the initial source of the sound dictates how large the initial vibration is.
- A gentle tap on a drum produces a small vibration and thus a sound wave with small amplitude (a soft sound).
- A hard strike on the same drum produces a large vibration and a sound wave with large amplitude (a loud sound).
Understanding Amplitude Visually
While sound waves are often depicted graphically, it's important to remember this representation shows the displacement or pressure variation over time. The "height" of the wave from its resting position represents the amplitude.
Consider this simple representation:
| Amplitude | Loudness |
|---|---|
| Larger | Louder |
| Smaller | Softer |
This table quickly summarizes the core relationship: the greater the amplitude, the greater the perceived loudness or volume.
In summary, the amplitude is the physical characteristic of a sound wave that directly correlates with the subjective perception of its loudness or volume, being set by the intensity of the original vibrating source.
