14.4 Sound Interference and Resonance

• A driving force (such as your voice in the example) puts energy into a system at a certain frequency, which is not necessarily the same as the natural frequency of the system.
• Over time the energy dissipates, and the amplitude gradually reduces to zero- this is called damping.
• The natural frequency is the frequency at which a system would oscillate if there were no driving and no damping force.
• The phenomenon of driving a system with a frequency equal to its natural frequency is called resonance, and a system being driven at its natural frequency is said to resonate.
• Beats are produced by the superposition of two waves with slightly different frequencies but the same amplitude.
• This wave fluctuates in amplitude, or beats, with a frequency called the beat frequency
• The lowest resonant frequency is called the fundamental, while all higher resonant frequencies are called overtones.
• All resonant frequencies are multiples of the fundamental, and are called harmonics.