The maximum distance between the vibrating object and the equilibrium position is called amplitude, which is equal to the maximum displacement in numerical value. The amplitude is a scalar, expressed in meters or centimeters. Amplitude describes the vibration amplitude of an object, also called natural frequency (natural period).

The initial phase is a measure of the position of the wave in its period at a specific moment: whether it is at the peak, trough or at some point in between. It is a measure to describe the change of signal waveform, usually in degrees (angles), also known as phase angle. When the signal waveform changes periodically, one period of the waveform is 360? . It is often used in scientific fields, such as mathematics, physics and electricity.