Sound Card Components and Digital Audio Formats

2. Sound Card Components

The design of sound cards has three distinct parts:

• The ADC (Analog-to-Digital Converter): Responsible for transforming digital information from the analog signal input line to which you connect a microphone or other sound source.
• The DAC (Digital-to-Analog Converter): Does just the reverse. Since digital information, it generates the analog signal that can be reproduced by speakers or headphones connected to the output line.
• The DSP (Digital Signal Processor): The subsystem that provides the ability for digital sound processing. Its functions include digitally manipulating sound to create effects such as echo or reverb, for example.

3. Audio Formats

Digital information processed by a sound card is stored in specific file formats described below.

MIDI Files

A peculiarity of MIDI files is that they do not sound exactly alike when played by two different sound cards.

The MIDI format is the standard of excellence in the world of electronic music. Examples include electronic instruments, synthesizers, sound cards, and samplers.

Digitized Sound Files

These files originate from the digitization of some normal analog sound source, such as a microphone or tape recorder.

Unlike what happens with the MIDI format, a digitized sound file should sound exactly the same on two different computers.

Digitized sound formats are the substitutes for old analog formats such as tape or vinyl records.

There are two main types of digital audio format:

• Formats that use data compression techniques: The most important are OGG, MP3, AC3, and WMA.
• Uncompressed formats: The CDA format used by commercial CDs, as well as WAV and PCM.

4. Sound Card Connections

Sound cards plug into the computer's motherboard using the ISA, PCI, or USB bus. It should be noted that the requirements for relaying information from sound cards are much lower than those for video cards.

• The most common are PCI now, but a generalization of the new PCI-E standard is preferred by manufacturers in the near future.
• USB sound cards usually offer the highest performance, often oriented toward the professional audiovisual industry. This is because they are complex and may include a large number of connectors that would not fit comfortably inside a standard computer case.

As for the external connectors on sound cards, the most common are a microphone input, a line input, and an audio output to connect speakers or headphones.