What are the physics of a telephone?
Speaker's Vocal Chords ===
- The person speaking into the phone passes air by their vocal chords making a basic tone, the mouth then shapes the tones into words. Audible Sound Waves are produced that propogate toward the phones microphone.
- The microphone or transducer will respond to the sound waves and convert mechanical energy into electical energy. This is typically through the reverse mechanices of a speaker. In this case, the cone shaped "floating" mechanical piece reacts to the sound waves of the person speaking into the phone. This creates an oscillating motion that moves a electrical coil around a magnetic field. This produces oscillating electrical voltage/current in proportion to the speed that the microphone oscillates. At the output of the microphone is a sinusoidal electrical wave form.
- The analog electrical signal has to be digitized so that we can take advantage of computer processing in the transmission. An Analog to Digital Converter is used.
- Sending the entire raw signal takes too long. The signal is passed through a modified Fast Fourier Transform FFT routine to come up with the basic waveform coefficients.
- The person being called picks up their receiver when their phone rings and the process reverses itself.