Sound Card Facts

Feature support

Additional features on sound cards provide higher quality or added functions. Some typical sound card features are listed below: -DirectSound 3D allows a computer to play audio in surround sound -EAX is a high definition sound tech originally developed for video games. This tech provides such realistic nuances that audio can actually cue gamers. -THX is a sound quality standard, originally created for film, now available on sound cards. This is a sound card feature that allows computers to present theater quality sound output. -Dolby Digital is a tech that broadcasts sound at a frequency the human ear can hear and diminishes collateral sound. This is a sound card feature that allows computers to present higher quality sound output. -DTS (Digital Theater Systems) Digital requires an optical reader to decode physical data and send it to a computer for processing. This is a sound card feature that allows computers to present theater quality sound output. MIDI (Musical Instrument Digital Interface) is a protocol for recording and playing audio created on digital synthesizers. This feature allows the computer to become an integrated component to a musical instrument.

Sound Card

An expansion card (or a component of the MOBO) that manages sound input and output. Because computers use digital data, sound cards must convert analog sound into digital data, and digital data into analog sound. The following components are used to do this: -The Analog to Digital Converter(ADC) converts analog sounds into digital data. -The Digital Signal Processor (DSP) is an on-board processor that reduces the CPU load. -The Digital to Analog Converter (DAC) converts digital data into analog sound (in preparation to be played on speakers).

Analog input and output

Analog output jacks allow you to play sound on your computer on external devices: -The speaker out connector sends signal to external speakers. This signal is amplified and the computer controls the sound level that is sent -The line out connectors send audio to other sound devices. This signal is unamplified. Analog input jacks allow you to record audio through the sound card. -The line-level (line in) connector receives signals from Cd players and musical instruments coming from the line-out port of the other devices. -The mic-level (microphone in) connector receives signals from microphones

Additional ports

In addition to audio and outport ports, some sound cards also include the following ports: -MIDI/joystick port to interface with MIDI sound devices or game controllers. -Firewire -Some high-end audio cards include HDMI video processors and video output, combing the features of an audio card with a video card. The sound card might have 1 or 2 HDMI ports (for input and/or output).

Bus support

Many newer MOBOs have a built in sound chipset. You can also add audio through an expansion card in a bus (such as PCI or PCIe).

Digital audio

Most audio devices, such as stereo consoles, TVs, and speakers require analog audio. Newer devices, such as some CD players, DVD players, and HDTVs, are capable of processing digital audio signals. Digital audio support in a sound card: -Allows you to play digital audio directly from an internal CD player -Allows for compression of audio data to support Dolby Digital or DTS surround sound. -Can use fiber optic cables to eliminate electrical interference. Sound cards support digital audio in the following ways: -An internal connector on the sound card connects to a digital audio output connector on a CD/DVD drive. Through this connection, you can play CDs directly through the sound card. -An internal connector on the osund card sends HD audio, such as from a DVD or Blu-ray disc, to an audio pass-through on a video card. This allows the HD audio signal to be combined with the video signal through an HDMI connector -Sony/Philips Digital Interface Format (S/PDIF) is a consumer standard for digital audio. These external connectors allow input and output between other digital audio-capable devices.

Sampling rate

Sampling rate is the number of analog signal samples taken over a period of time. Sample rates are expressed in cycles per second, called hertz (1,000 hertz = 1 kilohertz) . A high sampling rater gives ma more accurate represenatation of the sound. Ex of sampling rate: -8kHz (telephone) A sampling rate of 8 kHz is adequate for conversation because the human voices full range is about 4 kHz. -22kHz (radio quality) -44 kHz (CD quality) This sample rate can accurately reproduce the audio frequencies up to 20,500 hertz, covering the full range of human hearing. -48 kHz (Digital TV, DVD movies) -96 kHz (DVD audio) -192 kHz used by: *LPCM (Linear Pulse Code Modulation), a DVD-music production format. *BD-ROM (Blu-ray Disc ROM) and HD-DVD (High-Density-DVD), two competing next generation optical disc formats providing HD video and high density data storage. Higher sample rates require more bits of data. For example: -8 bit sound cards: 256 -16 bit sound cards: 65, 536 -20 bit sound cards: 1,048,576 -24 bit sound cards: 16,777,216 -32 bit sound cards: 4,294,967,296 THE BIT PORTION OF A SOUND CARD'S SAMPLING SIZE FOES NOT CORRESPOND WITH THE BUS SIZE.

Sound Card file types

Sound card drivers and other software save digital audio into several different file types. Common file types include: -WAV (Windows standard), a widely used and compatible file type -AIFF (Audio Interchange File Format), the Mac equivalent of the WAV. -AU (UNIX standard), supported by most Web browsers. -MP3 (MPEG-1 Layer 3), a highly effective audio compression standard -AAC (Advanced Audio Coding), also known as MPEG-2, a compression expected to replace MP3. -RA or RAM (Real Networks), developed for streaming audio files. Requires proprietary software -WMA (Window Media Audio), a highly compatible standard developed to compete with Real Audio -MIDI, not a true audio file, but contains data to reproduce sounds through electronic synthesis.

Channels

Sound is split into multiple channels, which can increase the sound quality, making it more realistic. Some standard channel configs are as follows: -2 channel audio is stereo. Examples of 2 channel audio include standard TV and radio -4 channel audio is quadraphonic audio, an early attempt at surround sound. -6 channel, also known as DTS (Digital Theater System) -5.1 channel audio, also know as surround sound, has 5 audio channels (delivered on 5 strategically placed speakers) and 1 effects channel (delivered via a subwoofer). The commercial name for this tech is Dolby digital -7.1 channel has 7 audio channels (delivered on 7 strategically placed speakers) and 1 effects channel (delivered via a subwoofer). This is the first technology providing error correction. The commercial name for this tech is SDDS (Sony Dynamic Digital Sound).