Introduction To Pc Sound Card

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Introduction to PC Sound Card Nowadays our PCs are equipped with all the gadgets that are required by us in our day-to-day life. You need not to buy a sophisticated CD/DVD player or a Hi-Fi music station if you have bought a modern PC. A single PC replaces lots many electronic equipments that are used in our daily life. Do you know how do your PC generate/ record sound. This article gives an introduction about the PC sound card that does excellent job for you without letting you know. Introduction A sound card does a minimum of four tasks. It functions as • Synthesizer • MIDI interface • Analog/digital converter (A/D), when sound is recorded from a microphone. • Digital/analog converter (D/A), when the digital sounds have to be reproduced in a speaker. The synthesizer The synthesizer delivers the sound. That is, the sound card generates the sounds. Here we have three systems: • FM synthesis, Frequency Modulation • Wave table • Physical modeling The cheapest sounds card use the FM technology to generate sounds simulating various instruments. Those are true synthesizers. The sounds are synthetic – it may sound like a piano, but it is not. FM synthesis generates sound like artificial sounds. Wave tables Wave table is the best and most expensive sound technology. This means that the sounds on the sound card are recorded from real instruments. You record, for example, from a real piano and make a small sample based on the recording. This sample is stored on the sound card. When the music has to be played, you are actually listening to these samples. When they are of good quality, the sound card can produce very impressive sounds, where the "piano" sounds like a piano.

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Physical modeling Physical modeling synthesis has arrived as a third sound producing technology. It involves simulating sounds through programming. The process is supposed to be rather cumbersome, but it should yield a number of other advantages. The basic quality of a sound card can be tested by playing a MID file. Then you can easily hear the difference. There is also a difference in how many notes (polyphony) can be played simultaneously. If you want to compose your own music on your PC, you use the sounds available on your sound card. The greater works you want to write, the more "voices" you will need.

MIDI MIDI (Musical Instrument Digital Interface) is a specification, which was developed in the 1980's to communicate between synthesizers. Since then MIDI has also become the standard, which allows programs to play music through the PC sound card. MIDI is a computer standard music format. You write compositions - musical events - in the MIDI format. The MIDI files do not contain the sounds but a description of how the music is to be played. The sounds are in your sound card. For example a MIDI sequence can describe the hit on a piano key. The MIDI sequence describes: • • • •

The The The How

instrument note strength of the key hit long to maintain the note

The only thing that is not covered is the sound of the instrument - that is created in the sound card, and is totally dependent on the sound card quality. A MIDI recording is thus a recording of music on "note level," without sound. It is played by a module, such as a sound card, that can generate the sounds of the instrument. MIDI files do not occupy much space as compared with the pure sound (WAVE files). Therefore they are often used over Internet. MIDI interface for keyboards A musical keyboard can be connected to the sound card with a connector. That is called a MIDI interface. You can buy special PC musical keyboards, or you can use one of the

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keyboard that is available in music stores. It will work as long as the MIDI connectors match. You connect your DIN connector to the piano keyboard. In the other end of the cable is a DB15 connector to the sound card. Then you can play from the piano keyboard through the sound card. Of course it requires a program that can handle music, but it works. The A/D conversion When you connect a microphone to the sound card, you can easily record your own voice on the PC. The result is a small WAVE file which holds a digital recording of the sound, which reached the microphone. The sound is analog, the file is digital – the transformation is done in the A/D converter in the sound card. This sound recording is called a sampling. It can be done in various qualities: • 8 bit or 16 bit sampling • 11, 22 or 44 KHz (how many thousand times per second the sound will be recorded) • Stereo or mono Stereo sampling at 16 bit and 44 KHz gives the best quality, but the Wave files will take up quite a bit more space. The sound of the future Until now PC sound has been totally dominated by the Sound Blaster card. All sound cards had to be compatible with Sound Blaster, or it would not sell. Obviously that is due to the numerous game programs, which require a SB compatible sound card. The new sound cards break away from the Sound Blaster compatibility. This break involves many facets. Below I will describe some of the tendencies in the sound technology. Sound over the PCI bus Newer sound cards can be connected on the PCI bus. The SB compatibility requires the old ISA bus, which is really antique today. With PCI you gain different advantages: • The IRQ problems disappear. • Signal/noise ratio can be improved with 5 dB. • There is sufficient bandwidth (capacity for data transmission). • The sound card workload for the CPU is less.

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We can drop the ISA bus, which takes up unnecessary space on the PC system board. The problem in moving the sound to the PCI bus involves existing software. First of all old DOS games, which expect and demand the Sound Blaster card with its IRQ- and DMA number. They will not work with the new cards, unless special solutions are implemented. Sound over the USB bus We will experience very high quality sound systems, when the new USB bus is implemented. The difference is that the sound card in the PC will work totally digital. The sound signals are in digital form when they are sent out on the USB channel: Inside the PC there is a lot of electric (static) interference from many sources. That can affect the integrity of the signals in the sound module. With USB the noise sensitive digital/analog conversion will take place in the speaker, and this results in a superior quality. Both Philips and Altec Lansing produce USB speakers. In the future we will see Hi-Fi speakers with built-in amplifier and converter, which can receive pure digital signals (via USB). These speakers will randomly be able to interpret data from Hi-Fi equipment, PC, TV/video and other sources. Surely we will also see sound cards and speakers for the FireWire bus, which is somewhat similar to USB.