As demonstrated above, it is possible to hear the perfect unison with the help of the beat frequency. In a group playing situation such as an orchestra, if some member is out of tune, the overall sound quality degrades due to the occurrence of beat. Once the unison sound is mastered, the rest of the consonant sounds will be much easier to learn. A pure tone is generated by a sinewave generator. Similarly, a pure color light is generated by a laser device.
Human hearing is a non-linear system.
When a pure tone is impinged on the ear drum, a series of harmonics are also heard. A violin tone ideally should contain only the harmonic series. A violin string, in principle, only generate harmonic sounds. The sounds are composed of the fundamental frequency and the integer multiples of the fundamental frequency. Since the surface area of the string is small, therefore it will not emit audible sound.