Sound functionality can also be integrated into themotherboard, using components similar to those found on plug-in cards. The integrated sound system is often still referred to as asound card. Sound processing hardware is also present on modernvideo cards withHDMI to output sound along with the video using that connector; previously they used aS/PDIF connection to the motherboard or sound card.
Typical uses of sound cards or sound card functionality include providing the audio component for multimedia applications such as music composition,editing video or audio, presentation, education and entertainment (games) and video projection. Sound cards are also used for computer-based communication such asvoice over IP andteleconferencing.
A common external connector is themicrophone connector. Input through a microphone connector can be used, for example, byspeech recognition orvoice over IP applications. Most sound cards have aline in connector for an analog input from a sound source that has higher voltage levels than a microphone. In either case, the sound card uses ananalog-to-digital converter (ADC) to digitize this signal.
Some cards include asound chip to support the production ofsynthesized sounds, usually for real-time generation of music and sound effects using minimal data and CPU time.
The card may usedirect memory access to transfer the samples to and frommain memory, from where a recording and playback software may read and write it to thehard disk for storage, editing, or further processing.
An important sound card characteristic ispolyphony, which refers to its ability to process and output multiple independent voices or sounds simultaneously. These distinct channels are seen as the number of audio outputs, which may correspond to a speaker configuration such as 2.0 (stereo), 2.1 (stereo and sub woofer), 5.1 (surround), or other configurations. Sometimes, the termsvoice andchannel are used interchangeably to indicate the degree of polyphony, not the output speaker configuration. For example, much oldersound chips could accommodate three voices, but only one outputaudio channel (i.e., a single mono output), requiring all voices to be mixed together. Later cards, such as theAdLib sound card, had a 9-voice polyphony combined in 1 mono output channel.
Early PC sound cards had multiple FM synthesis voices (typically 9 or 16) which were used for MIDI music. The full capabilities of advanced cards are often not fully used; only one (mono) or two (stereo) voice(s) and channel(s) are usually dedicated to playback of digital sound samples, and playing back more than one digital sound sample usually requires a softwaredownmix at a fixed sampling rate. Modern low-cost integrated sound cards (i.e., those built into motherboards) such asaudio codecs like those meeting theAC'97 standard and even some lower-cost expansion sound cards still work this way. These devices may provide more than two sound output channels (typically 5.1 or 7.1surround sound), but they usually have no actual hardware polyphony for either sound effects or MIDI reproduction – these tasks are performed entirely in software. This is similar to the way inexpensivesoftmodems perform modem tasks in software rather than in hardware.
In the early days ofwavetable synthesis, some sound card manufacturers advertised polyphony solely on the MIDI capabilities alone. In this case, typically, the card is only capable of two channels of digital sound and the polyphony specification solely applies to the number of MIDI instruments the sound card is capable of producing at once.
Modern sound cards may provide more flexibleaudio accelerator capabilities which can be used in support of higher levels of polyphony or other purposes such as hardware acceleration of 3D sound,positional audio and real-time DSP effects.
^abThe Tandy 1000 and the PCjr used the same sound chip, but the Tandy 1000 used the Audio IN pin, whereas the PCjr did not. This allowed the Tandy to produce the speaker sound at the same time as the SN74689
Connectors on the sound cards are color-coded as per thePC System Design Guide.[2] They may also have symbols of arrows, holes and soundwaves that are associated with each jack position.
Sound cards forIBM PC–compatible computers were very uncommon until 1988. For the majority IBM PC users, the internalPC speaker was the only way for early PC software to produce sound and music.[3] The speaker hardware was typically limited tosquare waves. The resulting sound was generally described as "beeps and boops" which resulted in the common nicknamebeeper. Several companies, most notablyAccess Software, developed techniques for digital sound reproduction over the PC speaker likeRealSound. The resulting audio, while functional, suffered from the heavily distorted output and low volume, and usually required all other processing to be stopped while sounds were played. Other home computers of the 1980s like theCommodore 64 included hardware support for digital sound playback or music synthesis, leaving the IBM PC at a disadvantage when it came to multimedia applications. Early sound cards for the IBM PC platform were not designed for gaming or multimedia applications, but rather on specific audio applications, such as music composition with theAdLib Personal Music System,IBM Music Feature Card, andCreative Music System, or on speech synthesis like DigispeechDS201,Covox Speech Thing, and Street ElectronicsEcho.
In 1988, a panel of computer-game CEOs stated at theConsumer Electronics Show that the PC's limited sound capability prevented it from becoming the leading home computer, that it needed a $49–79 sound card with better capability than current products, and that once such hardware was widely installed, their companies would support it.Sierra On-Line, which had pioneered supportingEGA andVGA video, and 3-1/2" disks, promised that year to support the AdLib, IBM Music Feature, andRoland MT-32 sound cards in its games.[4] A 1989Computer Gaming World survey found that 18 of 25 game companies planned to support AdLib, six Roland and Covox, and seven Creative Music System/Game Blaster.[5]
One of the first manufacturers of sound cards for the IBM PC was AdLib,[3] which produced a card based on theYamaha YM3812 sound chip, also known as the OPL2. The AdLib had two modes: A 9-voice mode where each voice could be fully programmed, and a less frequently usedpercussion mode with 3 regular voices producing 5 independent percussion-only voices for a total of 11.[b]
Creative Labs also marketed a sound card called the Creative Music System (C/MS) at about the same time. Although the C/MS had twelve voices to AdLib's nine and was a stereo card while the AdLib was mono, the basic technology behind it was based on thePhilips SAA1099 chip which was essentially a square-wave generator. It sounded much like twelve simultaneous PC speakers would have except for each channel having amplitude control, and failed to sell well, even after Creative renamed it theGame Blaster a year later, and marketed it throughRadioShack in the US. The Game Blaster retailed for under $100 and was compatible with many popular games, such asSilpheed.
A large change in the IBM PC-compatible sound card market happened when Creative Labs introduced theSound Blaster card.[3] Recommended by Microsoft to developers creating software based on theMultimedia PC standard,[6] the Sound Blaster cloned the AdLib and added a sound coprocessor[c] for recording and playback of digital audio. The card also included agame port for adding ajoystick, and the capability to interface to MIDI equipment using the game port and a special cable. With AdLib compatibility and more features at nearly the same price, most buyers chose the Sound Blaster. It eventually outsold the AdLib and dominated the market.
Roland also made sound cards in the late 1980s such as the MT-32[3] andLAPC-I. Roland cards sold for hundreds of dollars. Many games, such as Silpheed and Police Quest II, had music written for their cards. The cards were often poor at sound effects such as laughs, but for music were by far the best sound cards available until the mid-nineties. Some Roland cards, such as the SCC, and later versions of the MT-32 were made to be less expensive.
By 1992, one sound card vendor advertised that its product was "Sound Blaster, AdLib, Disney Sound Source and Covox Speech Thing Compatible!"[7] Responding to readers complaining about an article on sound cards that unfavorably mentioned theGravis Ultrasound,Computer Gaming World stated in January 1994 that, "The de facto standard in the gaming world is Sound Blaster compatibility ... It would have been unfair to have recommended anything else."[8] The magazine that year stated thatWing Commander II was "Probably the game responsible" for making it the standard card.[9] The Sound Blaster line of cards, together with the first inexpensiveCD-ROM drives and evolving video technology, ushered in a new era ofmultimedia computer applications that could play back CD audio, add recorded dialogue tovideo games, or even reproducefull motion video (albeit at much lower resolutions and quality in early days). The widespread decision to support the Sound Blaster design in multimedia and entertainment titles meant that future sound cards such asMedia Vision'sPro Audio Spectrum and the Gravis Ultrasound had to be Sound Blastercompatible if they were to sell well. Until the early 2000s, when the AC'97 audio standard became more widespread and eventually usurped the SoundBlaster as a standard due to its low cost and integration into many motherboards, Sound Blaster compatibility was a standard that many other sound cards supported to maintain compatibility with many games and applications released.
Three early ISA (16-bit) PC sound cards showing the progression toward integrated chipsets
When game companySierra On-Line opted to support add-on music hardware in addition to built-in hardware such as thePC speaker and built-in sound capabilities of theIBM PCjr andTandy 1000, what could be done with sound and music on the IBM PC changed dramatically. Two of the companies Sierra partnered with were Roland and AdLib, opting to produce in-game music forKing's Quest 4 that supported the MT-32 and AdLib Music Synthesizer. The MT-32 had superior output quality, due in part to its method of sound synthesis as well as built-in reverb. Since it was the most sophisticated synthesizer they supported, Sierra chose to use most of the MT-32's custom features and unconventional instrument patches, producing background sound effects (e.g., chirping birds, clopping horse hooves, etc.) before the Sound Blaster brought digital audio playback to the PC. Many game companies also supported the MT-32, but supported the Adlib card as an alternative because of the latter's higher market base. The adoption of the MT-32 led the way for the creation of theMPU-401,Roland Sound Canvas andGeneral MIDI standards as the most common means of playing in-game music until the mid-1990s.
EarlyISA bus sound cards werehalf-duplex, meaning they could not record and play digitized sound simultaneously. Later, ISA cards like the SoundBlaster AWE series and Plug-and-play Soundblaster clones supported simultaneous recording and playback, but at the expense of using up two IRQ and DMA channels instead of one.Conventional PCI bus cards generally do not have these limitations and are mostly full-duplex.
Sound cards have evolved in terms of digital audio sampling rate (starting from 8-bit11025 Hz, to 32-bit,192 kHz that the latest solutions support). Along the way, some cards started offeringwavetable synthesis, which provides superiorMIDI synthesis quality relative to the earlierYamaha OPL based solutions, which usesFM synthesis. Some higher-end cards (such asSound Blaster AWE32,Sound Blaster AWE64 andSound Blaster Live!) introduced their own RAM and processor for user-definable sound samples and MIDI instruments as well as to offloadaudio processing from the CPU. Later, the integrated audio (AC'97 and laterHD Audio) prefer the use of a software MIDI synthesizer, for example,Microsoft GS Wavetable SW Synth inMicrosoft Windows.
With some exceptions,[d] for years, sound cards, most notably theSound Blaster series and their compatibles, had only one or two channels of digital sound. Early games andMOD-players needing more channels than a card could support had to resort to mixing multiple channels in software. Even today, the tendency is still to mix multiple sound streams in software, except in products specifically intended for gamers or professional musicians.
As of 2024, sound cards are not commonly programmed with the audio loopback systems commonly calledstereo mix,wave out mix,mono mix orwhat u hear, which previously allowed users to digitally record output otherwise only accessible to speakers.
Lenovo and other manufacturers fail to implement the feature in hardware, while other manufacturers disable thedriver from supporting it. In some cases, loopback can be reinstated with driver updates.[10] Alternatively, software such asvirtual audio cable applications can be purchased to enable the functionality. According to Microsoft, the functionality was hidden by default in Windows Vista to reduce user confusion, but is still available, as long as the underlying sound card drivers and hardware support it.[11]
Ultimately, the user can use theanalog loophole and connect the line out directly to the line in on the sound card. However, in laptops, manufacturers have gradually moved from providing 3 separate jacks with TRS connectors – usually for line in, line out/headphone out and microphone – into just a single combo jack with TRRS connector that combines inputs and outputs.
The number of physical sound channels has also increased. The first sound card solutions were mono. Stereo sound was introduced in the early 1980s, andquadraphonic sound came in 1989. This was shortly followed by5.1 channel audio. The latest sound cards support up to 8 audio channels for the7.1 speaker setup.[12]
A few early sound cards had sufficient power to drive unpowered speakers directly – for example, two watts per channel. With the popularity of amplified speakers, sound cards no longer have a power stage, though in many cases they can adequately drive headphones.[13]
Professional sound cards are sound cards optimized for high-fidelity, low-latency multichannel sound recording and playback. Their drivers usually follow theAudio Stream Input/Output protocol for use with professional sound engineering and music software.[e]
Professional audio interfaces often have industry-standard inputs in addition to analogue audio, in this caseADAT,TDIF, andS/PDIF.
Professional sound cards are usually described asaudio interfaces, and sometimes have the form of external rack-mountable units usingUSB,FireWire, or an optical interface, to offer sufficient data rates. The emphasis in these products is, in general, on multiple input and output connectors, direct hardware support for multiple input and output sound channels, as well as higher sampling rates and fidelity as compared to the usual consumer sound card.[14]
On the other hand, certain features of consumer sound cards such as support for3D audio, hardware acceleration invideo games, or real-time ambiance effects are secondary, nonexistent or even undesirable in professional audio interfaces.[citation needed]
The typical consumer-grade sound card is intended for generic home, office, and entertainment purposes with an emphasis on playback and casual use, rather than catering to the needs of audio professionals. In general, consumer-grade sound cards impose several restrictions and inconveniences that would be unacceptable to an audio professional. Consumer sound cards are also limited in theeffective sampling rates and bit depths they can actually manage and have lower numbers of less flexible input channels.[15] Professional studio recording use typically requires more than the two channels that consumer sound cards provide, and more accessible connectors, unlike the variable mixture of internal—and sometimes virtual—and external connectors found in consumer-grade sound cards[citation needed].
In 1984, the firstIBM PCjr had a rudimentary 3-voice sound synthesis chip (theSN76489) which was capable of generating three square-wave tones with variableamplitude, and a pseudo-white noise channel that could generate primitive percussion sounds. The Tandy 1000, initially a clone of the PCjr, duplicated this functionality, with the Tandy 1000 TL/SL/RL models adding digital sound recording and playback capabilities. Many games during the 1980s that supported the PCjr's video standard (described asTandy-compatible,Tandy graphics, orTGA) also supported PCjr/Tandy 1000 audio.
In the late 1990s, many computer manufacturers began to replace plug-in sound cards with anaudio codec chip (a combined audioAD/DA-converter) integrated into themotherboard. Many of these usedIntel'sAC'97 specification. Others used inexpensiveACR slot accessory cards.
From around 2001, many motherboards incorporated full-featured sound cards, usually in the form of a custom chipset, providing something akin to fullSound Blaster compatibility and relatively high-quality sound. However, these features were dropped when AC'97 was superseded by Intel'sHD Audio standard, which was released in 2004, again specified the use of a codec chip, and slowly gained acceptance. As of 2011, most motherboards have returned to using a codec chip, albeit an HD Audio compatible one, and the requirement for Sound Blaster compatibility relegated to history.
Several Japanese computer platforms, including the MSX, X1, X68000, FM Towns and FM-7, have built-inFM synthesis sound fromYamaha by the mid-1980s. By 1989, the FM Towns computer platform featured built-inPCMsample-based sound and supported theCD-ROM format.[16]
The custom sound chip onAmiga, named Paula, has four digital sound channels (2 for the left speaker and 2 for the right) with 8-bit resolution[f] for each channel and a 6-bit volume control per channel. Sound playback on Amiga was done by reading directly from the chip RAM without using the main CPU.
Mostarcade video games have integrated sound chips. In the 1980s it was common to have a separate microprocessor for handling communication with the sound chip.
Melodik sound card with the AY-3-8912 chip for theDidaktik
ZX Spectrum with Fuller soundbox
Turbo Sound board manufactured by NedoPC, revision A
The earliest known sound card used by computers was theGooch Synthetic Woodwind, a music device forPLATO terminals, and is widely hailed as the precursor to sound cards and MIDI. It was invented in 1972.
Certain early arcade machines made use of sound cards to achieve playback of complex audio waveforms and digital music, despite being already equipped with onboard audio. An example of a sound card used in arcade machines is theDigital Compression System card, used in games fromMidway. For example,Mortal Kombat II on the Midway T-Unit hardware. The T-Unit hardware already has an onboardYM2151 OPL chip coupled with an OKI 6295 DAC, but said game uses an added-on DCS card instead.[17] The card is also used in the arcade version of Midway andAerosmith'sRevolution X for complex looping music and speech playback.[g]
MSX computers, while equipped with built-in sound capabilities, also relied on sound cards to produce better-quality audio. The card, known asMoonsound, uses aYamaha OPL4 sound chip. Prior to the Moonsound, there were also sound cards calledMSX Music andMSX Audio for the system, which usesOPL2 andOPL3 chipsets.
TheApple II computers, which did not have sound capabilities beyond rapidly clicking a speaker until theIIGS, could useplug-in sound cards from a variety of manufacturers. The first, in 1978, wasALF's Apple Music Synthesizer, with 3 voices; two or three cards could be used to create 6 or 9 voices in stereo. Later ALF created theApple Music II, a 9-voice model. The most widely supported card, however, was theMockingboard. Sweet Micro Systems sold the Mockingboard in various models. Early Mockingboard models ranged from 3 voices in mono, while some later designs had 6 voices in stereo. Some software supported use of two Mockingboard cards, which allowed 12-voice music and sound. A 12-voice, single-card clone of the Mockingboard called thePhasor was made by Applied Engineering.
TheZX Spectrum that initially only had a beeper had some sound cards made for it. Examples include TurboSound[18] Other examples are the Fuller Box,[19][20] and Zon X-81.[21][22]
The Commodore 64, while having an integratedSID (Sound Interface Device) chip, also had sound cards made for it. For example, the Sound Expander, which added on an OPL FM synthesizer.
ThePC-98 series of computers, like their IBM PC cousins, also do not have integrated sound contrary to popular belief, and their default configuration is a PC speaker driven by a timer. Sound cards were made for theC-Bus expansion slots that these computers had, most of which used Yamaha's FM and PSG chips and made by NEC themselves, although aftermarket clones can also be purchased, and Creative did release a C-Bus version of the SoundBlaster line of sound cards for the platform.
Devices such as theCovox Speech Thing could be attached to the parallel port of an IBM PC and fed 6- or 8-bit PCM sample data to produce audio. Also, many types of professional sound cards take the form of an external FireWire or USB unit, usually for convenience and improved fidelity.
Sound cards using thePC Card interface were available before laptop and notebook computers routinely had onboard sound. Most of these units were designed for mobileDJs, providing separate outputs to allow both playback and monitoring from one system, however, some also target mobile gamers.
USB soundcards are external devices that plug into the computer viaUSB. They are often used in studios and on stage byelectronic musicians includinglive PA performers andDJs. DJs who useDJ software typically use sound cards integrated intoDJ controllers or specialized DJ sound cards. DJ sound cards sometimes have inputs with phonopreamplifiers to allowturntables to be connected to the computer to control the software's playback of music files withvinyl emulation.
The USB specification defines a standard interface, the USB audio device class, allowing a single driver to work with the various USB sound devices and interfaces on the market. Mac OS X, Windows, and Linux support this standard. However, some USB sound cards do not conform to the standard and require proprietary drivers from the manufacturer.
Cards meeting the olderUSB 1.1 specification are capable of high-quality sound with a limited number of channels, butUSB 2.0 or later is more capable with their higher bandwidths.
The main function of a sound card is to play audio, usually music, with varying formats (monophonic, stereophonic, various multiple speaker setups) and degrees of control. The source may be a CD or DVD, a file, streamed audio, or any external source connected to a sound card input. Audio may be recorded. Sometimes sound card hardware and drivers do not support recording a source that is being played.
Sound cards can be used to generate (output) arbitrary electrical waveforms, as any digital waveformplayed by the soundcard is converted to the desired output within the bounds of its capabilities. In other words, sound cards are consumer-gradearbitrary waveform generators. A number of free and commercial software allow sound cards to act likefunction generators by generating desired waveforms from functions;[23] there are also online services that generate audio files for any desired waveforms, playable through a sound card.
Sound cards can also be used to record electrical waveforms, in the same way it records an analog audio input. The recording can be displayed by special or general-purpose audio-editing software (acting as anoscilloscope) or further transformed and analyzed. A protection circuit should be used to keep the input voltage within acceptable bounds.[24][25]
As general-purpose waveform generators and analyzers, sound cards are bound by several design and physical limitations.
Sound cards have a limited sample rate, typically up to 192 kHz. Under the assumptions of theNyquist–Shannon sampling theorem, this means a maximum signal frequency (bandwidth) of half that: 96 kHz. Real sound cards tend to have a bandwidth smaller than implied by the Nyquist limit from internal filtering.[24]
As with all ADCs and DACs, sound cards produce distortion and noise. A typical integrated sound card, theRealtek ALC887, according to its data sheet has distortion about 80 dB below the fundamental; cards are available with distortion better than −100 dB.
Sound cards commonly suffer from some clock drift, requiring correction of measurement results.
Sound cards have been used to analyze and generate the following types of signals:
Sound equipment testing. A very-low-distortion sinewave oscillator can be used as input to equipment under test; the output is sent to a sound card's line input and run throughFourier transform software to find the amplitude of each harmonic of the added distortion.[26] Alternatively, a less pure signal source may be used, with circuitry to subtract the input from the output, attenuated and phase-corrected; the result is distortion and noise only, which can be analyzed.
Longwave radio. A 192 KHz sound card can be used to receive radio signals up to 96 kHz. This bandwidth is enough for longwavetime signals such as theDCF77 (77.5 KHz). A coil is attached to the input side as an antenna, while special software decodes the signal.[28][29] A sound card can also work in the opposite direction and generate low power time signal transmissions (JJY at 40 KHz, using harmonics).[30]
To use a sound card, theoperating system (OS) typically requires a specificdevice driver, a low-level program that handles the data connections between the physical hardware and the operating system. Some operating systems include the drivers for many cards; for cards not so supported, drivers are supplied with the card, or available for download.
DOS programs for the IBM PC often had to use universalmiddleware driver libraries (such as theHMI Sound Operating System, theMiles Audio Interface Libraries (AIL), theMiles Sound System etc.) which had drivers for most common sound cards, since DOS itself had no real concept of a sound card. Some card manufacturers providedterminate-and-stay-resident drivers for their products. Often the driver is a Sound Blaster and AdLib emulator designed to allow their products to emulate a Sound Blaster and AdLib, and to allow games that could only use SoundBlaster or AdLib sound to work with the card. Finally, some programs simply had driver or middleware source code incorporated into the program itself for the sound cards that were supported.
Microsoft Windows uses drivers generally written by the sound card manufacturers. Many device manufacturers supply the drivers on their own discs or to Microsoft for inclusion on Windows installation disc. USB audio device class support is present from Windows 98 onwards.[31] Since Microsoft'sUniversal Audio Architecture (UAA) initiative which supports HD Audio, FireWire andUSB audio class standards, a universal class driver by Microsoft can be used. The driver is included withWindows Vista. ForWindows XP,Windows 2000 orWindows Server 2003, the driver can be obtained by contacting Microsoft support.[32] Almost all manufacturer-supplied drivers for such devices also include this universal class driver.
A number of versions ofUNIX make use of the portableOpen Sound System (OSS). Drivers are seldom produced by the card manufacturer.
Mockingboard support on the Apple II is usually incorporated into the programs itself as many programs for the Apple II boot directly from disk. However a TSR is shipped on a disk that adds instructions to Apple Basic so users can create programs that use the card, provided that the TSR is loaded first.
^If the number and size of connectors is too large for the space on the backplate, the connectors will be off-board, typically using a breakout box, an auxiliary backplate, or a panel mounted at the front.
^The percussion mode was considered inflexible by most developers; it was used mostly by AdLib's own composition software.
^This was likely anIntel microcontroller relabeled by Creative.
^TheE-MU card family, the Gravis GF-1 and AMD Interwave support up to 32 channels.
^ASIO drivers are also available for a range of consumer-grade sound cards.
^With patches, 14/15-bit resolution could be accomplished at the cost of high CPU usage.
^Revolution X used fully sampled songs from the band's album that transparently looped – an impressive feature at the time the game was released.
^Up untilLinux kernel 2.4, OSS was the standard sound architecture for Linux, although ALSA can be downloaded, compiled and installed separately for kernels 2.2 or higher. But from kernel 2.5 onwards, ALSA was integrated into the kernel and the OSS native drivers were deprecated. Backward compatibility with OSS-based software is maintained, however, by the use of the ALSA-OSS compatibility API and the OSS-emulation kernel modules.
^Installing an LG driver on many Dells with Sigmatel 92xx chip, including the Inspiron 6400 and other models can add support for stereo mix.[1]Archived 2013-05-20 at theWayback Machine Reference dates from 2007 and covers Windows XP and Vista.
^abEric Bogatin."Turn Your Computer's Sound Card into a Scope".For example, the Sabrent low cost ($8) USB sound card has an internal 16-bit ADC that can sample up to 196 kS/sec, but has a limited input frequency range from about 100 Hz to 20 kHz. The Waveforms software tool can drive this USB sound card.
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