Final answer:
The pitch of a sound is determined by the fundamental frequency, with higher frequencies leading to higher pitches and vice versa. Musical instruments and voices create unique sounds through a combination of overtones, which are multiples of the fundamental frequency. Adjusting the tension in strings or changing the shape of vocal cavities can alter these frequencies and thus the pitch.
Step-by-step explanation:
The pitch of a sound is indeed determined by the presence of the fundamental frequency. A higher frequency produces a higher pitch, while a lower frequency results in a lower pitch. When a pipe is placed on the ground, changing from an open to a closed state at one end, the fundamental frequency changes. This alteration of frequency leads to a change in the observed pitch because the wavelength associated with the fundamental frequency has altered. For example, the fundamental frequency for a tube open on both ends is calculated as f1 = Vw/2L, where Vw is the speed of the wave and L is the length of the pipe.
Each musical instrument has a unique mix of overtones, which, along with the fundamental frequency, shapes the character of the sound produced. The overtones are multiples of the fundamental frequency; thus, when a string's tension is adjusted, the fundamental frequency and the associated overtones change, leading to a variation in pitch. This principle is a key aspect of how string instruments are tuned. Additionally, the difference in pitch and timbre between different instruments, or between human voices, can be attributed to the particular combination of overtones that are produced.