(Shelly Cashman Series) Gary B. Shelly, H. Albert Napier, Ollie N. Rivers-Web design_ introductory concepts and techniques -Cengage Learning (2008)

Audio and Video Elements 169
Figure 6-10 RealPlayer and Windows Media Player are both used for playing streaming audio.
EDITING AUDIO FILES Although you might never edit audio files, understanding
certain aspects of audio file editing can help you make better choices when selecting audio
files for your Web site. Audio must be in digital format to be used on the Web. Analog
audio files can be digitized, or encoded, using sound-editing software, such as Audacity or
WaveLab 6 ® . You edit digital audio files by manipulating certain audio aspects, including
message size and audio channel selection. Keep in mind these guidelines for creating and
editing audio files for the Web:
• Keep recorded audio messages or music clips short; simply stated, shorter audio
messages equal smaller files. Include only necessary content in the audio message.
• Select a mono audio channel to reduce file size; mono (one-channel) and stereo
(two-channel) are the two more well-known audio channels. Selecting a mono
audio channel reduces the file size approximately by half over a stereo audio
channel. A mono audio channel is also the best choice for an audio message. The
choice of mono or stereo for a music file depends, in part on the desired sound
quality and the type of file compression.
• Use an 8 kHz sampling rate for voice-only audio and 22 kHz sampling rate for
music audio. The sampling rate, measured in kilohertz (kHz), refers to the amount
of samples obtained per second during the conversion from analog to digital sound.
For example, a sampling rate of 48 kHz yields higher quality audio and also a much
bigger file than a sampling rate of 11.127 kHz or 8 kHz.
• Use an 8-bit audio file for voice and 16-bit audio file for music. Bit depth is a
measure of audio quality; the greater the number of bits, the higher the audio
quality level, but the larger the file.