When attempting to play an audio CD no sound comes through the external speakers. However, I am able to play music stored on the hard drive and CDs containing MP3 files. Interestingly, I can hear the music if I plug-in headphones. The computer is running Windows 98.

The likely problem is you do not have an audio cable connecting your CD drive to your sound card. The traditional way of playing audio CDs is a cable which is connected directly between the CD-ROM drive and the sound card. When playing an audio CD, the signal is sent directly from the CD-ROM drive to the sound card, by-passing the main computer processor. The reason you can play MP3 CDs is because the MP3 files on the CD are not sent directly to the sound card (since they are not audio tracks), but instead are processed through the computer processor and software, which then outputs the audio signal to the sound card. This also explains why you can play music stored on the hard drive. So, to fix the problem you will need to purchase an audio cable for your CD-ROM drive. This cable will go between the analogue audio connector on the rear of the CD-ROM drive, to the analogue audio connector on the sound card. These cables are inexpensive, but to find one you will probably need to go to a computer repair store who should have these cables in the spare parts bin. If you have trouble finding a cable, please let me know and I should be able to assist in pointing you in the right direction.

However, you may not need to find a cable if your CD playback software supports Digital Audio Extraction (DAE). When the playback software supports this feature, the audio signal from the CD is accessed as data output from the CD drive (across the computer IDE bus, just like accessing information from a data CD, such as an MP3 CD), instead of using the analogue audio cable connection. In this case, the audio signal is processed through the computer processor and software and is then outputted to the sound card (see support.microsoft.com/kb/271647 for more information). To use DAE, you will need to run a player which supports this payback method. Windows Media Player version 7 and above supports DAE. If you are not already running this version (or above) of Windows Media Play, you can download Windows Media Player 7.1 for Windows 98 (or, if you are running Windows 98 SE, you can download Windows Media Player 9) from www.microsoft.com/downloads. At the website, click the ‘Windows Media’ link on the left-hand side of the screen, then on the page that next appears, find the link for your required version of Windows Media Player. If audio CDs still don’t play after installing the player, you will need to open the Windows Media Player settings and enable DAE. However, be aware that when using DAE on a slower-performing machine, you may find that system performance decreases or the CD playback quality degrades (e.g. audio skipping). This is because using DAE consumes CPU time and also IDE bus bandwidth, as the audio signal is being processed by the CPU, rather than going direct to the sound card (with no CPU involvement) as is the case when using the analogue audio cable. If you find your system cannot handle DAE, then you will probably need to buy an audio cable for the most efficient playback of audio CDs.