Digital Audio

Digital audio, as opposed to analog audio, uses a numerical representation of the signals amplitude and frequency and stores these numbers as pulses of magnetic energy. If you were to zoom into a digital signal it would look more like steps than a smooth line. This is because the signal is rounded up or down to the closest digital number, or quantization level.


Sampling


Sampling the process of taking slices of the analog signal at a fixed rate and converting them into digital data. The rate that the samples are taken is called the sampling frequency. The amount of samples taken per second is the sampling rate. In order for a signal to be encoded successfully the sampling rate must be twice the highest frequency.


Word Clock


A word clock is used to synchronize the sampling frequency of all devices used in a recording system. Its kind of like setting them all to the same rhythm. To avoid data loss and distortion, all digital devices in a system must be set to a single word-clock master so that their sampling frequencies will be exactly the same.


Bit depth


Bit depth or, also called bit resolution or word length, is the number of bits per sample that a digital device (such as an A/D converter, or a multi track recorder) uses to convert or store data. The greater the number of bits in a digital sample, the more accurate the digitized description of the instantaneous value of the audio waveform.


Sampling Frequency


The rate that the samples are taken is called the sampling frequency. The amount of samples taken per second is the sampling rate. Sampling is the process of taking slices of the analog signal and converting them into digital data.


Digital Connections


There are two common connections used in the digital world. These are the AES/EBU and SPDIF. The AES/EBU (American Engineering Society and the European Broadcasting Union) interface is a professional digital audio connection which uses balanced XLR connectors. SPDIF (Sony Phillips digital interface) uses either an unbalanced phono connection or optical connection. It is the consumer version of AES/EBU.

Tutorial 7: The Analog to Digital Process


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Main Menu

Tutorial 1. Sound Waves
An introduction to sound waves

Tutorial 2. Phase Relationships
Explaines what happens when sound waves interact

Tutorial 3. Absorption, Reflection, Diffraction, and Diffusion
The things that can happen when sound encounters an object

Tutorial 4. The Human Ear
A discussion of the different parts that make up the ear. This section also covers hearing loss and prevention.

Tutorial 5. Analog Audio
A discussion about the analog audio format

Tutorial 6. Digital Audio
All about digital audio

Tutorial 7. The Analog to Digital Process
How analog sound waves are converted into digital data.

Tutorial 8 Microphones
A discussion of the three most common professional microphone types. Also information on pick-up patterns.

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