Sound can be recorded in one of several digital formats and linked to an HTML page.
The files produced are called audio files or digital audio files or sound clips. A popular
file format is the wav file. Wav files can also be incorporated into other
objects, including PowerPoint presentations. Digital audio files contain data
representing samples of the electrical signal generated by the sound. Each sample records
the value of the signal with a specified degree of accuracy. At the low end, sampling is
done 8000 times per second and 8 bits of information is recorded each time. At the high
end, recording is done using stereo microphones, so two sets of samples are produced.
Sampling is done over 40,000 times per second and 16 bits of information is kept for each
sample. The first case produces a smaller file and the second case a larger file. The
playback of the first case will not sound as good as the playback of the second. What I
have described here as the low end is roughly equivalent to what we hear on a telephone
line. The high end is described often as CD quality and is considered to be the limit of
human hearing.
Sound files
To make a sound file you need the hardware (microphone and speakers or earphones) and
the software. The software programs Sound Recorder and Wave Studio are generally
available. To edit and enhance your sound files, you can use the shareware version of
CoolEdit. These tools are easier to use than to write down all the directions. They and
others for recording sound give you the flexibility of setting the quality parameters
indicated above.
The format for the HTML tag for a wav file is the following:
...<a href="ring.wav">sound</a>
In this case, clicking on 'sound' will cause the digital audio file ring.wav
located on the same drive, same directory as the HTML file, to be played IF the browser
has been set properly. Special media files such as wav files use what are termed
Helper programs. For this case, assuming it does not work the first time (and that your
computer speakers work properly), you need to click on Options, then General Preferences,
then Helpers. Next, find wav files (it may be called audio/x-wav) in the
list of file types, and then browse to find the program called mplayer.exe. It is
generally in the 'windows/' directory. Alternatively, call for help from the people
staffing the computer lab.
To test if your browser is set up properly, click here. A small wav
file will be downloaded and played. You should hear the sound of a telephone ringing. If
you don't hear it, then you will need to set up your browser as described above.
