Whenever you see the speaker icon
there is a short audio sample available. To listen to these samples you will need a computer with a sound card and software for playing MP3 files.
You must have a functioning sound card. If you are unsure then test it with another application to make sure that it is working properly.
If your computer runs Windows, look for the presence of a speaker icon in the system tray at the bottom right hand corner of the screen. It should look like one of these:
Windows XP 
Older versions of Windows 
If you do not see this then check your sound card is connected and the drivers have been installed.
On most desktop computers the speakers or headphones must be connected to a socket on the back of the computer. There may also be a headphone socket on the front, by the CD/DVD player, but this will generally not give audio output for anything other than CDs/DVDs.
For windows users, double click on the speaker icon in the system tray at the bottom right hand corner of the screen:
Windows XP 
Older versions of Windows

A mixer screen should appear which will look similar to this:
Make sure that none of the boxes marked 'Mute' are ticked, and that the volume sliders under 'Volume Control' and 'Wave' are turned up.