1. Multiple of Fundamental Frequency:
Each overtone has a frequency that is a whole number multiple of the fundamental frequency. For instance, the first overtone is twice the frequency of the fundamental, the second is three times, the third is four times, and so on.
2. Harmonic Series:
The fundamental frequency and its overtones form the harmonic series. Each overtone corresponds to a specific harmonic, labeled as the second harmonic, third harmonic, fourth harmonic, and so forth, The fundamental is the first harmonic.
3. Timbre and Sound Quality:
The presence and relative intensity of overtones largely determine the unique sound quality, or timbre, of a musical instrument of a voice. Different instruments and voices produce unique overtone spectra, contributing to their distinctive characters and recognizable sounds.
4. Resonance and String Length:
In stringed instruments, overtones are created by the vibration of different segments of the string. Harmonic nodes (points of least vibrations) occur at specific points along the string, dividing it into vibrating segments with different lengths. Shorter segments generate the higher overtones.
5. Resonant Bodies and Cavities:
Instruments like the guitar and violin have a soundboard or resonating body. This acts as a natural filter that amplifies certain overtones while dampening others to create a specific sound characteristic.
6. Helmholtz Resonance:
A special case of resonance is Helmholtz resonance, which occurs in enclosed resonant cavities. These cavities, found in instruments like wind instruments and enclosed resonating chambers, create distinctive formants frequencies related to the overtone series.
7. Harmonicity and Dissonance:
The harmonic series provides a sense of harmoniousness due to the simple whole-number ratios between frequencies. However, overtone with frequencies that are not integer multiples of the fundamental generate dissonant, or conflicting, sounds.
Understanding the relationship between overtones and the fundamental frequency is key to comprehending the science behind the quality and perception of sound. While this article covered some fundamental aspects, the field of acoustics and psychoacoustics dives much deeper into the complexities of sound and its interaction with the human ear and brain.
