Lesson 3 - Posted on 2013-03-21 by Griffin Plack

This Lesson introduces the basics of Digital Audio. The way a computer represents sound is similar to the way a film represents motion, by taking many photos and putting them one after another in a sequence a film is made. With sound, we put discrete samples together in a sequnce to create the illusion of a continuos wave. A transducer is a device that converts one form of energy to another. The job of a microphone is to convert the change in air pressure cause by the vocalist into an analogous charge in electrical voltage. An Analog-to-Digital Converter(ADC) receives the voltage from the sample and hold device and assigns a numerical value to each amplitude. This process is know as quantization. The numbers are stored in the computer as a string of binary digits. A Digital-to-Analog Converter (DAC) converts each number to a voltage and communicates those voltages to an amplifier to incresase the amplitude of the voltage. Harold Nyquist discovered that the computer can only accurately represent frequencies up to half the sampling rate. This discovery is known as the Nyquist Theorem. The sample rate is the number of samples per second taken from a continuos signal. The consumer-level sample rate is 44,100 Hz.