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INTRODUCTION TO SOUND
As the Internet download speeds increase and compression methods grow better, sound becomes commonplace on the World Wide Web. Websites make interactive noises, have soundtracks, and talk to their users. To make use of the Internets sound capabilities, youll first have to learn how sound works, and what the basic terms mean. Well also talk about equipment and software that you may or may not need when recording and editing sound. Ready?
Oh, okay, Ill wait
How about now? Good.
What is Sound?Sound is actually vibration. Most often, the sounds we hear are passed through vibrating air. The air vibrates in a certain way, passing waves of vibration to any objects it encounters. When the vibration reaches your eardrums, it pulsates the sensitive membranes in your ear, and is interpreted by your brain as sound. To create sound, your computer feeds electricity at a certain wavelength through a stretched membrane (the speaker), causing it to vibrate. The speaker passes along the vibration into the air, creating a sound. You can create your own sound vibrations by using your vocal cords. Feel your throat and hum.
Sound File Attributes
Hz, Rental Car or Indispensable Sound Term? Hz, pronounced "Hertz" is a kind of measurement. Hz measures cycles of something happening. A wheel goes around one time, thats a Hz. The sun rises and sets, thats a Hz, too. If a sound wave goes up and down, thats one Hz.
Directly translated into sound, a Hz is one vibration. A standard music CD holds sound at a level of 44,100 Hz. This means that the sound can change, or vibrate, 44,100 times every second. When creating sound files, youll have the option to save at different Hz levels.
Bit Rate"Bit" means binary digit, and is numerically represented by a zero or a one. Computers use zeros and ones to make up their whole language. In when referring to sound, bits are used to tell the computer how much electricity to feed into your speakers to create a vibration. The level of electrical signal dictates the height of each wave. If you used two bits, you would be able to come up with four different levels to describe the signal strength of each sound wave (Hz): 00, 01, 11, 10
Standard music CDs use 16 bit sound, which means that 16 zeros and ones are used to describe the level (height) of each sound wave. With 16-bit sound, you can have 256 different levels of signal strength. In other words, a binary statement 16 bits in length is used to describe the level of signal 44,100 times per second.
The more levels of sound, the better quality your sound will seem, but as you add bits, youve also adding more information for users to download.
Sound File TypesSounds, like other computer files, can be saved in different formats. Next, in your web design course Youll learn how to create sounds in each of the following formats.
.WAV WAV is a sound file developed by Microsoft for use on windows based machines. WAV is also the file format for standard music CDs. The WAV file uses interesting algorithms to compress raw sound without a loss in quality. On a PC, you will need to export as a WAV before you configure the sound for streaming.
.AIFF Originally developed by Apple, the "Audio Interchange File Format" is mostly used by Silicon Graphics and Macintosh machines. AIFF files are easily converted to other file formats, but can be quite large. One minute of 16-bit stereo audio sampled at 44.1kHz usually takes up about 10 megabytes. AIFF is often used in high-end applications where storage space is not a consideration.
MP3MP3 is a type of compression that can dramatically reduce file size without drastically reducing sound quality. MP3 works by, among other things, chopping off all sounds that are outside of the normal human range of hearing. You will need a sound player to listen to MP3s. Your computer probably came with an MP3 player, but you might want a better one. WinAmp is recognized by many to be the best Mp3 Player. Its available for free at www.winamp.com For those that are interested, MP3 stands for "MPEG Third Layer" or "MPEG-1, audio layer 3".
RealAudioDeveloped by Progressive Networks, RealAudio was the first format to allow for real time streaming of music and sound over the web. Listeners are required to download the Realplayer to enjoy sound in RealAudio Format. The Realplayer can also stream video and is currently in use by millions of Internet users worldwide.
CDsYoure not going to be using CDs over the Internet, but I think this stuff is interesting, so here you go: A CD doesnt have little zeros and ones on it. It has notches. A laser shoots up and bounces off of the CDs reflective coating. The computer can tell if the laser went in a notch or not by the time the laser takes to make the round trip. If the CD player decides that the laser went in a notch, thats a one. If the laser bounces back without hitting a notch, thats a zero. Keep in mind that the laser is bouncing back at the speed of light and that there have to be 1376 available notches for every second of CD. Impressive, no? Audio CDs can hold up to 74 minutes of music in standard WAV format.
Whats a Sound Card and Which One Do I Need?A sound card is basically a separate computer with its own processor and RAM. When the computer sees a sound instruction, it shuttles the task out to the appropriate card for processing. This leaves the main processor free to do other things. If your computer has speakers and plays sounds, you already have a sound card, but for high quality recording and playback, you may want to upgrade. Sound cards are usually measured by their on-board memory and by how many bits they can process for each wavelength. If you can afford it, youll want to get at least a 32 bit sound card. This will handle 16 bit stereo recordings. You can actually spend big bucks on a soundcard, but thats not really necessary for web work. Soundblaster www.soundblaster.com makes a fine line of soundcards. Youll probably want the "Live" version.
MicrophonesIf youre going to be recording, youll need a microphone to plug into your sound card. The quality of your mic will directly effect the quality of your sound file. If you buy a junky microphone, youll know it, and your users will know it.Your local music supply store should be able to help you select a good microphone. Just tell them what youre trying to do with it. If in doubt, the Shure SM58 is a great voice microphone, and is almost indestructible. When rock musicians show off by slamming the mic onto the stage, its almost always a SM58. SpeakersYou can have the best sound card in the whole world, but if your speakers suck, you still wont get good sound from your computer. Good sound on your end is important. You need to hear what your sounds really sound like if youre going to be recording, editing, and streaming. Youve got a couple of solutions for quality sound reproduction:
SpeakersYoull need good speakers, positioned on either side of your monitor. You can: �. Hook your stereo up to your computer. �. Buy good speakers for your computer. �. Use Headphones
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