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1.9. Interactive sound design case study

Interactive CD-ROM is the closest medium that web audio developers can look to for guidance on creating sophisticated soundtracks. The basic principles for interactive CD-ROM design can be directly applied to the Web. Both mediums share similar technical limitations, bandwidth challenges, and logistical concerns.

There is much to learn by examining the mistakes and innovations made by those who pioneered interactive sound design in the CD-ROM medium. Here are some approaches to common problems.

1.9.1. Selecting sounds

Emphasizing lower frequencies over higher-pitched sounds greatly improves audio playback quality over the Web. If you know you are going to lose a lot of high-end frequencies through extreme compression for example, then avoid using high-pitched sounds at the outset.

Most high frequency sounds above 5,000 Hz and 10,000 Hz, such as whistles and shattering glass are lost when sampling down to 8-bit or when using extreme compression algorithms. For example, buzzing flies in a forest ambiance will lose its characteristic sound when reduced to 8-bit and will become random, indistinguishable noise. An effective strategy would be to add the lower frequency sound of owl hoots to your forest mix instead of high-frequency buzzing flies.

1.9.2. Timing loops

In late 1994, co-author Josh Beggs and audio engineer Reid Ridgway embarked on an eight-month soundtrack production for EMI Records. The project was to create a CD-ROM for the multiplatinum band Queensrÿche called the "The Promised Land" -- an interactive rock-and-roll adventure game (see Figure 1-23) containing a separate fantasy world for each of the five band members. Each band member developed a unique theme, environment, and palette of sounds for his fantasy world. But due to technical constraints and limitations in CD-ROM storage capacity, the soundtrack had to be limited to an 8-bit, 22,050 Hz mono channel of audio.

Figure 1-23

Figure 1-23. The Queensrÿche Promised Land CD-ROM interactive adventure game

As sound designers, the task was to create a rich and compelling interactive soundtrack despite the limited bandwidth and resources. Designing for an uncontrollable sequence of events was a recurring challenge. We discovered two ways to conquer this challenge:

Practicing good audio etiquette: multimedia rules of the road

 

Building a site with audio and animation can be a risky endeavor. If you implement full-scale audio, someone is likely to get an error message. Most of the time it will have nothing to do with your code. Often error messages appear because of a browser configuration mistake or a client-side anomaly beyond your control.

 

The following steps can help minimize the negative impact of audio:

 
  • Inform your clients that using audio is a risk factor. Explain the drawbacks and benefits of a web soundtrack. Use audio with caution on web sites visited frequently for key information or used in the office during work hours. More conservative news and commerce sites should, at a minimum, incorporate button sounds for easier navigation and informative narration. Full-scale multimedia works best for entertainment and promotional web sites.

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  • If you are going to build a web site with a multimedia format such as Flash, Shockwave, or RealMedia, start with a home page that displays most of the important text and graphics in standard HTML format. For an example of this style, visit the Raspberry Media web site at http://www.raspberrymultimedia.com. If you construct most of the home page layout in HTML with your multimedia content playing in a smaller dedicated media window, you can avoid the undesirable situation of losing visitors who do not have the right plug-in or browser to view the home page. Embedding a smaller media window in your pages also reduces the file sizes of your animations and provides a sense of movement on the home page, as seen on the Raspberry Media web site.

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  • When possible, avoid music loops that repeat indefinitely. Make your loops fade out or stop after a reasonable number of cycles. Some sites tastefully include a "stop music" button on every web page that has an audio loop.



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