Final answer:
The frequency of sound, which translates to pitch, is mainly determined by the characteristics of the sound wave and the size of the musical instrument. Additionally, the Doppler effect influences frequency when there is relative motion between the source and observer. Human perception of loudness also varies with frequency due to ear sensitivity.
Step-by-step explanation:
What Determines the Frequency of Sound?
The frequency of sound is perceived as pitch and is determined by the characteristics of the sound wave, specifically the number of waves per unit of time. This is dependent on several factors including the size and shape of the musical instrument, and the relative motion between the source and the observer, known as the Doppler effect. For example, a smaller musical instrument like a tambourine typically produces sound waves with a higher frequency, leading to a higher pitch, whereas a larger instrument like a drum will produce sound waves with a lower frequency, resulting in a deeper sound. The frequency of sound waves produced by an instrument is typically measured in hertz (Hz).
Moreover, the speed of sound is largely independent of frequency within the audible range, which ensures that music from a marching band in a stadium, for instance, arrives in cadence for all listeners. High-frequency sounds have shorter wavelengths, and when there is relative motion towards the source, the frequency increases, while moving away decreases frequency. Lastly, the loudness of sound also interacts with frequency, as human ears have different sensitivities to different frequencies.