Lesson 3 – Introduction to Basics of Digital Audio (part 1) - Posted on 2013-09-27 by Danielle Jardine

Basics of Digital Audio

The best way to begin to understand how computers represent sound is to compare it to how motion is represented in a film. All a movie is, is a series of still photos taken in a rapid sequence at a constant rate. When the photos are played back in the same sequence and same rate our minds are tricked into thinking we are seeing one continuous motion. Its the same concept with digital music. We take multiple desecrate samples of the sound wave’s instantaneous amplitude. This information is then stored and reproduced latter at the same rate at which it was sampled creating the illusion of a continuous soundwave.

The continuously changing electrical voltage that is produced y a mic when someone or something plays sound through the microphone is sampled periodically and held at regularly spaced intervals. Each sample is held until the next one is taken. This process is called sample and hold (its also the name of the device that does this process). These samples are then sent to an Analog to Digital Converter (ADC) which turns the aptitude into numbers for the computer or storage device to read the digital information. The numbers are the binary code (1′s and 0′s) which is the computers way of storing information. When playing back this information the computer/storage device reads back the numbers and sends the code to a Digital to Analog Converter (DAC) at the same rate they were recorded. The DAC turns the numbers back into voltages which are then run through an amplifier which boosts the amplitude of the voltages so they can be heard through the speakers.

To be continued in Part 2 with Sample Rate, Nyquist Theorem and Bit Depth.