What describes the effect when two signals have a slight difference in frequency?

When two signals have a slight difference in frequency, the phenomenon that occurs is known as beating. This effect results from the superposition of the two signals, which causes periodic variations in amplitude. As the two waves overlap, they reinforce each other at certain intervals and partially cancel out at others, creating a pulsating sound or signal that fluctuates in intensity.

The frequency of the beating is determined by the difference in frequencies of the two signals; the closer the frequencies are, the slower the beats will be. This is commonly experienced in music where slightly detuned instruments can create a rich, shimmering effect due to the beating phenomenon.

Understanding this concept is essential in vibration analysis, as it helps in evaluating signals, diagnosing faults, and understanding the behavior of mechanical systems under varying loads. Beating can provide insights into the condition and performance of machinery by highlighting frequency changes that may indicate issues such as misalignment or wear.