Yale C/AIM Web Style Guide




Design and AV elements

Digital Video

Digital Audio

GIF Animation

Sound and music can be delivered quickly and effectively over the Web. High-quality audio files can be compressed so that they maintain their fidelity, yet the data rates required to deliver the file remain reasonable. This is especially true when using streaming audio.
But quality is imperative in web audio. Any type of digital data compresses best when it begins at the highest quality possible. For example, a blurry photograph will remain blurry when digitized, and file compression such as JPEG will only emphasize the blur. This is also the case with sound files. An audio file that begins its digital life with background noise or with a low dynamic range will be difficult to repair, and its flaws will be more apparent after the extensive downsampling and compression required to make the file web-deliverable.

File Processing
It is difficult to remove noise once it is present in a signal, so always try to record in the quietest place possible and take steps to reduce or eliminate environmental noise (e.g., turn off unneeded equipment, turn off or lower the ventilation system). However, if your recorded audio does have noise, you can reduce or sometimes eliminate it using the equalizer and noise gate features of sound editing software such as SoundEdit 16. One trick when using the equalizer to reduce noise is to raise each band individually until you find the one that contains the greatest amount of noise. If you can pinpoint the band that adds the most noise, you can lower that band and reduce the noise.

Example with noise

Example without noise

You can also use the equalizer to add substance to your audio files. In many cases your web audio will be played on built-in computer speakers and your audio may lack the punch you had intended. Using the equalizer to boost the mid-range frequencies will help fill out your sound, but be sure to check your files on a variety of systems to ensure that your sound stays balanced.
It is also a good idea to normalize your sound files. Normalization ensures that you are working with the loudest possible audio signal, and since you will lose volume due to downsampling for the web, normalizing is an easy step toward increasing the quality of your music and sounds. Normalizing a file finds the loudest peak in a file and then amplifies the entire file to make that peak's volume 100%.

Example without normalizing

Example with normalizing

Our recipe for creating web audio


Record the audio in the best possible setting with the best available equipment.
2. Digitize the audio at 44.1 kHz with a 16-bit sample rate.
3. Use SoundEdit 16 to edit and mix the audio.
4. Normalize the file.
5. Use Movie Cleaner Pro to perform downsampling from 44/16 to 22.050 kHz, 16-bit with IMA 4:1 compression, and to make the file fast-start QuickTime.


Essex, J. 1996. Multimedia Sound and Music Studio. New York: Random House Reference and Information Publishing, Inc.

Terran Interactive: Movie Cleaner Pro

Macromedia: SoundEdit 16
Copyright 1997 P. Lynch and S. Horton,
   all rights reserved. Yale University   Revised January 1997.