An overtone's a natural resonance of a system. Systems described by overtones are often sound systems, for example, blown pipes or plucked strings. If such a system's excited, a number of tones may be produced along with the fundamental tone. In simple cases, such as for most musical instruments, the frequencies of these tones are the same as (or close to) the harmonics (integer multiples of the fundamental frequency). An example for an exception's a circular drum, whose first overtone's 2.4 ti… (More on Overtones)