A harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency , i.e. if the fundamental frequency is `` f '' , the harmonics have frequencies 2 `` f '' , 3 `` f '' , 4 `` f '' , .
If `` f '' is the fundamental frequency ( that is , 1 `` f '' ) , then the `` harmonics '' have frequencies 2 `` f '' , 3 `` f '' , 4 `` f '' ... , and so on .