Sound waves. Tones and Vowels By Corina Bot, PhD

A mechanical wave is a wave that is not capable of transmitting its energy through a vacuum (i.e., empty space). Mechanical waves require a medium in order to transport their energy from one location to another. A sound wave is an example of a mechanical wave. An electromagnetic wave is a wave that is capable of transmitting its energy through a vacuum. Electromagnetic waves are produced by the vibration of charged particles. Electromagnetic waves that are produced on the sun subsequently travel to Earth through the vacuum of outer space.

Below is a diagram of a sound wave that has been changed into alternating current by a microphone. alternating currentmicrophone If the sound is made louder, the shape of the wave changes. The amplitude has gotten bigger because the sound is louder.amplitude

Period and Frequency of sound waves Low frequency High frequency

Period and Frequency of sound waves time ∆t∆t N cycles Period Frequency

256 Hz 512 Hz 4000 Hz FFT Spectrum of three tuning forks of 256 Hz, 512 Hz, and 4000 Hz Sound waves converted into alternating current by microphone

distinguish between low and high frequency waves based on amplitude. distinguish between the waves of a tuning fork and human voice by viewing a demonstration with a microphone sensor. calculate the period of the tuning fork waveform. compare the FFT spectrum for human voice when two vowels are spoken into the microphone. calculate the frequency of each of the tuning forks used. Conclusions: Students will be able to :