Designing Web Audio & CD-ROM

Recording techniques

Capturing a signal to tape or disk clean of excessive reverberation or noise is critical. You can always add effects later to enhance or alter a sound, but it is difficult to remove distortion and noise from the original source. Compression in the encoding process also degrades your sound slightly. The higher the quality of the original source material, the higher the quality of the final output to the Web. In addition to selecting the right equipment, properly setting up your studio and reducing noise on location also results in a cleaner signal.

Watch the levels: analog versus digital distortion

In analog recording it was often advantageous to apply distortion—that is, push beyond the maximum recording level “into the red” by about 9dB. Such analog distortion enriches the sound by first raising, and then compressing the level of quieter sounds. Furthermore, analog “tube” distortion often produces the pleasing effect of adding harmonics or tones to a voice or an instrument track.

Digital encoding, on the other hand, cannot quantify signals above 0dB. Thus, digital distortion produces unpleasant noise and unwanted clicks and pops, known as artifacts.

If your digital audio signal is in the red, turn down the input gain levels until the green LED lights are bouncing up and down below the 0dB point. Set your reference levels by having the voice-over artist or musician briefly play the loudest passage of the piece and turn your input levels down accordingly. Better ...