Pitch Depends on Vibrations and Waves

como e que e possivel o timbre depender da forma das vibrações (How is it that it is possible for the pitch to depend on the shape of the vibration / wave?)
- JOANA FREITAS (age 13)
colegio rainha santa isabel, coimbra

The pitch depends on how often a particle vibrates when a wave passes through, otherwise known as the frequency of the wave. How often does the pressure vary from high to low and back again? The higher the frequency (more vibrations), then the higher the pitch will be; the lower the frequency (less vibrations), the lower the pitch will be. Since frequency is the reciprocal of the period, the higher the frequency the more peaks and valleys within a given amount of time. Because sound waves in air travel atabout the same speed regardless of their frequency, high frequency also means more peaks and valleys in a a spatial picture of the sound wave. In other words, the wavelength of the high-frequency waves is shorter tha of low-frequency waves. Sorry, I don’t know how to insert an image, but there is a great website where you can see the different shapes of the waves in high and low pitches (frequencies) at:

Gloria

(published on 10/22/2007)