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This week's article takes a look at soundcards or, more to the point, the jargon used when soundcards are talked about. Doubtless you have seen adverts specifying "128 key polyphony" and "Features sound banks," but what do these terms actually mean? Read on!
Digitised Sounds These sounds are produced as a series of numbers with each number representing a musical note. As well as the pitch of a note, the MIDI instrument, volume and special effects can be stored as numbers. This is what .MID and RMI files are made up. You may notice that MIDI files are much smaller in size than their .WAV counterparts. This is because the computer already knows which "instrument" to play and the pitch of the note. You may notice in the previous paragraph that I used the term "MIDI." This stands for "Musical Instrument Digital Interface." What this means in English is that electronic instruments such as synthesisers and drum machines send numbers to each other that are converted into sounds. My own PC is connected to my MIDI keyboard (a Yamaha PSR400). This means that I can play the keyboard and get my PC to record a MIDI file. Once inside the PC, I can change the instruments, add effects and so on. It really DOES make writing music so much easier as my editing package can actually print sheet music of what I play - not always a desirable thing! Most decent soundcards store a sample of what various instruments sound like. This means that instead of a horrible electric whine (such as you used to get with Stylophones - remember them?), you get a true-sounding Violin, Trumpet or whatever. Cheaper cards use FM - Frequency Modulation that produces an electronic interpretation of what a real instrument sounds like. You can always tell them, as they always sound electronic. Sampled Sounds Sampled sounds (such as .WAV) files that are literally a recording made with a microphone. These sounds can be anything from a "pop" to a complete speech. They tend to larger than MIDI files as they take snap shot of the sound at various points. The more points read per second - the better the quality, as there are fewer gaps. Trouble is - the more points taken - the larger the file. CD quality is around 44KHz - that's 44000 points per second! A reasonable "voice" can be recorded at 11KHz.
The copyright of the article Sounding Off with Soundcards in PC Support is owned by Chris Cruickshank. Permission to republish Sounding Off with Soundcards in print or online must be granted by the author in writing.
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