What is the principal effect of sound wave frequency on hearing?

The principal effect of sound wave frequency on hearing is that it determines pitch. Frequency refers to the number of vibrations or cycles a sound wave completes in one second, measured in hertz (Hz). When the frequency of a sound wave is higher, it creates a higher pitch, which is perceived as a higher note in music or a shrill sound, while a lower frequency results in a lower pitch, perceived as a deeper note or bass sound.

Understanding pitch is essential for music and communication, as we differentiate sounds based on their frequencies. For example, the notes of a piano vary significantly in pitch due to the different frequencies they produce.

In contrast, loudness is affected by the amplitude of the sound wave, which is unrelated to frequency. Echoes are the result of sound reflecting off surfaces and do not depend on frequency; rather, they rely on the environment and distance between the sound source and the reflecting surface. Resonance involves specific frequencies at which an object vibrates, but again, this is a different concept from basic pitch perception, which is directly influenced by frequency.