Final answer:
Overtones are multiples of the fundamental frequency, not high-frequency tones, half increments, or restricted to speech. They are important elements of the timbre of musical instruments and voices, contributing to their distinctive sounds. Hence, option (c) is correct.
Step-by-step explanation:
Overtones are harmonics that are higher in frequency than the fundamental frequency. They are integral to the timbre or characteristic sound of a musical instrument or voice. Overtones are not high-frequency tones in general, nor are they half increments of the fundamental frequency.
Furthermore, overtones are not restricted only to speech sounds; they are found in all types of sound waves that can resonate, such as those produced by musical instruments. The correct answer is C) multiples of the fundamental frequency. Confusion may arise because the term 'harmonic' might be used interchangeably with 'overtone'. The first overtone is the second harmonic of the fundamental frequency.
The combination of fundamental and overtones can be present in various instruments, such as the trumpet and clarinet, which sound distinctively different even if they play the same fundamental note. This rich mix of overtones, modulated by the musician or speaker, gives each instrument and voice a unique characteristic.
In speech, much of the sound quality is determined by how the throat and mouth shape the resonant cavity and thus adjust the fundamental and combination of overtones.