The pitch of sound depends on:

1. Frequency:
The primary factor that determines the pitch of a sound is its frequency. Frequency refers to the number of vibrations or cycles of a sound wave per second and is measured in Hertz (Hz). Higher frequencies result in higher pitches, while lower frequencies produce lower pitches. For example, a high-pitched sound like that of a whistle or a bird chirping has a higher frequency, while a low-pitched sound like that of a bass guitar or a thunder rumble has a lower frequency.

2. Length of Vibrating Object:
The length of the vibrating object also influences the pitch of sound. When an object vibrates, it produces sound waves. Longer objects tend to vibrate at lower frequencies, resulting in lower pitches, while shorter objects vibrate at higher frequencies, producing higher pitches. This is why longer guitar strings produce lower pitches, while shorter guitar strings produce higher pitches.

3. Tension of the Vibrating Object:
The tension or tightness of the vibrating object affects the pitch of sound. A tightly stretched object, such as a drumhead or guitar string, will vibrate at a higher frequency and produce a higher pitch. Conversely, a loosely stretched object will vibrate at a lower frequency and yield a lower pitch. This is why tightening or loosening the strings of a musical instrument can alter its pitch.

4. Size and Shape of Resonating Cavities:
The size and shape of the resonating cavities, such as our vocal cords, also impact the pitch of sound. When we speak or sing, air passes through the vocal cords, causing them to vibrate and produce sound waves. The size and shape of our vocal cords determine the pitch of our voice. Larger vocal cords tend to produce lower pitches, while smaller vocal cords result in higher pitches.

5. Doppler Effect:
The Doppler effect can also affect the perceived pitch of sound. When a sound source moves towards an observer, the sound waves are compressed, increasing the frequency and resulting in a higher pitch. On the other hand, when the sound source moves away, the sound waves are stretched, decreasing the frequency and yielding a lower pitch. This effect is commonly experienced when a siren approaches and then passes by, causing the pitch of the siren sound to change.

In conclusion, the pitch of sound is determined by the frequency of the sound waves, the length and tension of the vibrating object, the size and shape of resonating cavities, and the Doppler effect. Understanding these factors helps explain why different sounds have different pitches and allows us to manipulate pitch in various ways, such as in music or speech.

Pitch depends on frequency but also on loudness and spectrum

In the introduction on sound, we saw that pitch depends primarily on frequency. However, it also depends, weakly on sound level. It depends, too, on harmonic content.