natural vibrational frequencies. We write these in ascending order, so that f i <f2<f3 The lowest frequency, fi is called the fundamental frequency(基频)” and the corresponding mode of oscillation is called the fundamental mode". the higher frequencies are called" overtones(泛音)”/2 with being the first overtone, f3 the second overtone, and so on In some systemsnatural vibrational frequencies. We write these in ascending order, so that . The lowest frequency, is called the “fundamental frequency(基频)”, and the corresponding mode of oscillation is called the “fundamental mode”. The higher frequencies are called “overtones(泛音)”, with being the first overtone, the second overtone, and so on. In some systems:    1 2 3 f f f 1 f 3 f 2 f nf1 f n =