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Audio Basics

ach of the following sub-sections concentrates on a specific aspect of sound, helping you understand sound terminology, decide what type of sound or sounds you’d like to put on your site, and what types of formats to consider.

You don’t need to follow these sections in order, but if you’ve never heard of the term “sample rate,” (don’t worry, neither did we) you may want to check out all of these sections at least once.

Thinking About Sound is an overview of how sound can enhance your site, and what things you need to consider before working with sound.
Sounding Off introduces the various types of sound: sound effects, voice and musical instruments.
Concepts discusses the bare bones of audio. Get ready to make sense of all those strange terms and foreign concepts.
Formats discusses the strengths and weaknesses of different formats.
Audio Issues discusses issues surrounding online sound and what they mean to you and your Web site.

Thinking About Sound
Add sound to your Web pages, and add a whole new dimension. Think about sound as a part of your Web site; it should harmonize with all the other aspects of your page, and it should enhance your page.

Adding sound to Web sites involves a three step process: authoring, distribution and playback. Authoring is the process of creating audio sound files. Distributing is the process of incorporating the sound into your site, and delivering the whole package to your readers. Playback is using the site and hearing the sounds in context.

Authoring
Think about how you’re going to get your sound. Some people create their own sound. Some people use recorded sound clips, which are somewhat like graphical clip art. Sometimes, you’ll hire a composer to create sounds for you.

As you think about the best way for you to get your sound, ask yourself the following questions:

Are you going to create the sound yourself? Depending on what type of sound you’d like to use, you may want a professional to create it for you. If you’d like to use music on your site, consider using a composer instead of creating it on your own. Musicians have an ear for what type of music works with what. Unless you’re a musician, (and that doesn’t include just singing in the shower every morning) you might want to consider an outside source. But you can easily create feedback sounds or sound effects yourself. You can even tape record your dog barking for a unique sound effect.

Creating sound yourself can be more economical than hiring a contractor or purchasing sounds from a sound disc, and it means your sounds are yours. You’ll have original sounds you know won’t be anywhere else.

But you risk having a less “professional” sounding page, or not having the sounds match the rest of your site when you create sound yourself. You also need to think about whether you have the time to create sounds from scratch.
Are you going to purchase sound clips from a CD-ROM? If you’d like to have neat sound effects, like blips and bleeps, going with a CD is sometimes the best choice?you’ll have plenty of cool sounds to choose from.

Buying sounds from a CD may be your fastest choice?call a 1-800 number and get the CD the next day?and may be the best choice for a tight deadline.

But, purchasing sounds from a sound disc is similar to purchasing graphic clip art. If the disc is popular, you, and many other people may be using the same sounds for your sites. Purchasing sound from a disc can also be expensive (again, very similar to purchasing graphic clip art). Also think about your budget, your time requirements and whether you want original sounds before purchasing a sound CD.
Are you going to hire a musician or audio master to create the sound for you? This may be your best choice if you’d like original music or sounds on your site (unless you’re a composer as well). It also may be the best choice for professional sounding voice-overs for a company training manual, or an online “tour.” Voice actors, sound experts and professional recording make a difference in how your site sounds.

However, using a professional can get expensive, and you need to consider how long it’ll take the musician to create the sound, test it out and make sure it works with your site. Always think about your budget and your time requirements when choosing sound.

Distributing Sound
Now that you have your sound, its time to put it into your HTML page and get it out to your readers. There are several different methods for embedding sound into your Web pages; we’ll go into these later.

When inserting audio into your site, you’ll follow many of the same rules as you would with inserting graphics:

Avoid large file sizes. The larger the file, the longer it takes to download. Sure, it might sound great, but if the file is huge, who’s going to stick around to listen to it?
Avoid having sound overkill. Sound works best when used well and in a way that is appropriate to your site. Sound is just one element among many, including design and content in your site.

When determining how much sound and what type of sound you’d like to use on your site, ask yourself the following questions:

What’s the purpose of sound on the site? Is it a corporate homepage or a rock band’s site? You need to consider the message of your site, and chose sound accordingly.
What kind of connections and equipment does your target audience have? If you’re working on an intranet, you’ll know what connection, browser and plug-ins your audience has. Otherwise, you need to adapt your site for different browsers, connection speeds, and provide access to any specific plug-ins you’re using.
How long are the site visitors willing to wait for the download? If you’re building a site for a rock band, the fans might be willing to wait a while for sound; but people searching for information unrelated to sound may get annoyed with long waits.
What physical environment is the reader in? If your reader is at work, make sure you tailor the type of sound to that environment, which may mean very little or at least quiet, sound.

Next you need to consider the type of site you’re working on. Is it a professional site? A homepage? Is the design and content conservative, or cutting-edge? Match your sound for the type of site you’re building. Having loud clips of techno music for a corporate site may not be what that company had in mind.

Playback
Once you have sound on your site, think about how your reader is going to play it back.

Will they mouseover a word and automatically hear the sound? This is an effective technique for providing immediate blurbs of sound and instant effect.

Or will you provide a pop-up box that contains sound controls?so your users can play, stop, pause, rewind, fast-forward or change the volume of the sound? Think about where and how big the pop-up boxes, if any, will appear. Providing a pop-up box is a good idea since it allows your readers to have complete control over the sound. This can eliminate embarrassing situations at work, or prevent someone from leaving your site because they dislike the sound.

Are you going to use a plug-in or a default player for playing back the sound? If you’re using a plug-in, provide a means (that is, a link to the download site) for your users to get the plug-in. Will you use a built-in plug-in, one that both Netscape and Internet Explorer support? Many readers dislike having to go elsewhere to obtain a plug-in before they view a Web site.

When controlling sound on your page, remember to make the playing-back experience as simple as possible for your users.

Sounding Off

Once you’ve decided that you want to use sound in your Web page you need to think about the sounds availible to you.

Many people automatically think of music when thinking of sound on the Web. But music is just one type of sound. Here’s a few types of sounds we’re all familiar with (Click on the links and then hit the play button on the player to hear an example of that sound):

Voice. Whether it be your 8-year-old niece’s voice, your voice, your golden retriever’s voice, or an entire choir, voices can add a nice affect. Voices work especially well for online “tours” of a company or a product.
Voice over instrumental. Maybe you wouldn’t want to hang out at a place that offers Kareokae nights, but it can add humor and a laid-back feeling to certain Web sites.
Musical Instruments. Whether it’s the sound of your brother playing the piano, or a clip of a rock concert, musical instruments work for many different sites.
Sound Effects. Blips, bleeps, sounds of crashing and banging, or any burst of sound works well for onmouseover sounds, or onclick sounds.

When considering types of sounds, consider your audience, the rest of your site, and the goal of your site. Think about what you’re trying to say and to whom.

You may find that voices work wonderfully for an online company training manual, but sound strange for the corporate Web page. Sounds of rippling water may work great on a page about rivers, but it’s probably not the best sound for a page about how to stop your kid from wetting the bed. Test different types of sounds on different pages.

Pay as much attention to the types of sound you’re using as you would with the type of images you’re using.

Basic Sound Concepts

When you start looking into putting audio on your Web site, and maybe purchase an audio editor, you’re going to be hit with a zillion new terms. This section defines basic sound terminology and concepts.

Acoustic	Pertaining to sound and the act of hearing.
Analog Sound	Refers to sound signals and energy, i.e., what you hear.
Bit	Bits and Kilobits are units of measurement for data transfer. A bit stands for “binary digit,” and it’s the smallest unit of computer data. Bits consist of 1’s and 0’s. Most audio files on the net have been recorded at a resolution of 8 or 16 bits. 16 bit is CD standard, but 8-bit is more useful for the Web because it’s smaller size equals less download time. The resolution bit rate determines the overall dynamic range of the output from an audio source. Each bit of resolution contributes approximately 6 decibels.
Decibel	Decibel, or Db, is a measure of the ears response to sound. or Db, is a unit to express relative difference in power, usually related to electrical or sound signals.
Digital Sound	When you put sound on your computer, the sound signals need to be transformed into a “language” that your computer can understand. Computers read sound signals once they’re in a binary code?a whole bunch of 0s and 1s. Binary code sound signals are known as digital signals.
Dynamic Range	A measure of the span between the quietest and the loudest sounds.
Resolution	The resolution refers to how many locations represent the waveform at each given sample. Think about what resolution means to your images?the more resolution, the better your image looks. It works the same way with audio files. Resolution is measured in terms of bps, or bits per second. Resolution equals the number of bits allocated for each sample or output value.
Sampling	An ADC (Analog to Digital converter) is a computer chip that’s used to convert analog signals into digital information. This process is called sampling. After you’ve converted sound to digital information, you can “view” this sound, in a graphic representation (looks like part of an EKG) with a sound editor program. You can slice this information, dice it, reverse the sound, do the “Alvin and the Chipmunks” effect by speeding up the sound, cut off as much of the waveform as you’d like, loop it and a whole bunch of other fun editing techniques. Digital signals need to be converted back to analog in order to hear them. TD>
Sample Rate	When editing sound you need to determine the sampling period or rate and the bit resolution. The sampling rate refers to the number of samples (or “bits” of sound) per second. The more samples per second, the better it sounds. The most common sample rates are 44.1k (which means 44,100 samples per second), 22.05k and 11k (actually 11,025). The ear is very picky. It requires an extraordinary amount of audio “samples” to hear a sound clip. The engineers who designed CDs decided that 44,100 ‘samples’ per second is what the ear needs to hear sounds accurately.

Audio Formats and Quality Levels

As discussed in the Quick Start, many different formats, or ways to record sound exist. Formats fall into two categories: described sound, such as MIDI, and recorded sound.

MIDI vs Audio
MIDI is a way to play sound files without taking up too much space. MIDI transmits commands?information about how to play certain sounds?but it does not transmit audio signals.

MIDI devices act as a middle point between the sound source and the computer.

MIDI files take up very little memory in the computer, and they download faster than digital sound files.

Recorded Sound
The three most popular audio (recorded sound) formats are AU (audio format), WAV (waveform audio) and AIFF or AIF (Audio Interchange File Format). .EA is another common format, used specifically for the Web. These formats can be used on both Netscape and Internet Explorer, and they allow decent compression and decent sound quality.

Many formats allow for 8 and 16-bit resolution. With smaller resolution (such as 8-bit) the file size is smaller, but the quality of sound isn’t as good.

Does Size Matter?
The number one consideration when working with sound on the Web is balance of file size and file quality. Sure, it would be nice if we could all put CD-quality stereo sound on our Web sites. It would also be nice if the pictures on our Web sites look exactly the same as they do on paper. But we all know that that’s usually not a good idea. What’s the point of having sound if your visitors need to wait 30 minutes in order to hear anything?

Better sound quality means more disk space and more waiting time. One minute of CD quality stereo sound takes up about 10MB of disk space, and takes about 10 minutes to hear it at modem speed. Your goal is to balance the sound quality with the file size. We’ll show you how to do this in our Designing with Sound section.

Sizes and Rates
Different types of music sound differently depending on which format they’re saved as, what the file size is, and what the sample rate is. As a general rule, when working with classical music, you’ll want to keep the file size around 16-bit, and the rate at 44k, for the best quality sound. For rock, you’ll want a 16-bit file size, and a 22 k sample rate. For speech, you can use an 8-bit file size, with an 11k sample rate.

The problem with using those guidelines for the Web, however, is that file size is much more important than sound quality, where in the non-Web world, sound quality is far more important than file size. When working with sounds for the Web, test specific compression rates for each of your sounds. All compression schemes make sound files sound worse, so you’ll need to determine what files sizes work best for you and your readers. If you can use a smaller file size, without affecting the quality of sound too much, you should. It saves waiting time for your visitors.

Audio Issues

Four major issues that you need to think about when working with audio are: whether to use self-contained or streaming audio, whether to require or avoid plug-ins for sound playback,ensuring that your files are yours to use and balancing quality with file size.

Self-Contained Audio vs. Streaming Audio

Self-contained audio files are files that do not require any additional applications to play the sound. They’re friendlier to load, because the site visitor doesn’t have to do anything or run off and attempt to find the right plug-in. But if it’s a large audio file, the page will take forever to load?and the user won’t hear anything until the whole page has loaded.
Data streaming allows users to play audio (and video) files before they’re completely downloaded. Part of the audio file is downloaded before the rest, which means that visitors to your site have something to entertain them while your graphics and text is loading. A drawback to many streaming audio technologies is that they require a plug-in.

Plug-in vs. No Plug-in?
Streaming audio would be a better option if it didn’t require users to download a plug-in. Plug-ins are a serious pain. Most browsers come with plug-ins already enabled for playing MID, WAV, AIF, AU and other formats.

And depending on who your audience is, as low as five percent of your users may have the plug-in required. After seeing a warning message that says, “you must have a plug-in to view this page,” many visitors will go elsewhere.

Whether or not you use a plug-in depends on your audience and the type of Web site you’re building. Plug-ins can allow you to play higher resolution sound files, and music can be downloaded faster, but if the user doesn’t have the plug-in, they might not go and get it just to listen to your site. That’s why it’s important to know your audience before you use specific plug-ins. If your audience is on an Intranet, you know whether everyone has a specific plug-in. Otherwise, you’re risking people going elsewhere.

Check out and download some popular Plug-ins.

Copyright Issues

The basic rule about copyright issues is this: Don’t steal someone elses’ music.

Sure, you own that U2 CD, but that doesn’t mean you can put a few songs from it on your Web site and not expect any negative consequences, like being sued. You need to get permission from the artist or the record company, and if they tell you to use only 10 seconds from a certain song, that’s what you’ll do. We’ll discuss copyright issues in more detail later, but just remember: if you didn’t create it yourself, or pay someone to create it for you, you don’t have all the rights to it.

Bandwidth
Sound takes up a lot of bandwidth, or space. Unless you want your visitors to wait 30 minutes or more to hear a single sound, you need to compress your sound files before you put them up on your Web site. That’s why we said there are two major issues regarding file size: balancing file size and file quality. Waiting around for sound is about as fun as going to the dentist. Keep your files as small as possible while still keeping a decent sound quality. Your visitors will thank you.

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