The harmonic balancer helps minimize torsional crankshaft harmonics and resonance. The interval between the first and second harmonics of the harmonic series is an octave. This vibration results in a periodic acoustic waveform comprising a fundamental frequency and its harmonics. Some musical instruments produce overtones that are slightly sharper or flatter than true harmonics. "Friction" opens with Lloyd playing octaves before Verlaine's ringing harmonics and series of descending scales. The guitar resonator is a device for driving guitar string harmonics by an electromagnetic field. Timbre is largely determined by the content of these harmonics. Sounds are produced by plucking open strings, stopped strings, and harmonics. The vocal folds generate a sound rich in harmonics. Theoretically square waves consist of odd harmonics only. Hz with detectable second and third harmonics. The other pitches are "harmonics", or "overtones". Voltage harmonics are mostly caused by current harmonics. The song opens with a section of clean single strings and harmonics. It is typically the case that voltage harmonics are indeed small compared to current harmonics.