Sound is one of our most crucial human senses for receiving information and it can be used very effectively for web sites. However, as you visit different web sites, the main time you come across sound is hearing some corny rendition of marching music, some vague familiar television show theme song, or tinker-toned Beethoven as soon as a web page loads. Like video, sound must be converted analog to digital, from audio waves that travel through air, to numerical representations of wave frequencies. It can be done as easily as talking into a microphone plugged into the back of your computer, to high end digital recording in a sound studio. In the end, you end up with a computer file that can be played back through a speaker and, again travels through the air to your ears.
Sound files come in many different formats, which creates another layer of alphabet soup confusion.
A comprehensive overview of the differences between them is beyond our tutorial, and we will just have to accept that we can have a sound file on a computer that can be sent over the Internet and played at the other end. One format is of special interest, MIDI, because it generally makes for the smallest sound files. Rather than digitizing the sound waves itself, in MIDI format sounds are represented as more or less text characters representing the notes on different types of instruments, and when it is played back, the computer uses a built in sound library to play back the designated note. Therefore, the data that sent is very small. Many sites offer sound in RealAudio format in which the sound files streams from a special web server to your web browser.