In physics and electronics amplitude is literally the maximum absolute value of a periodically varying quantity. In layman’s terms it is the strength of a signal or sound without regard to its content. Amplitude measurements of audio signals generally refer to the signal voltage, which is only one component of what determines power (watts), or the ability to do work. Thus it is important to understand that amplitude alone does not singly determine power (or loudness in audio), but does affect it. In the physical world the amplitude of a sound is measured in dB of SPL (Sound Pressure Level), which again does not define the true sound power or intensity (many people are confused about this), only the sound level at a point in time. We’ll cover this in more detail later when we define those words.