One of my customers recently purchased a new Dell Vostro 1720 laptop with Windows XP preinstalled. When I had the customer use Windows Live Messenger and I connected to the Vostro over the Internet, the customer experienced a pronounced audio echo from the laptop (the video worked fine). No one else that I initiated video conferences with had this audio echo problem.

I tried replacing the motherboard, to no avail—so the problem wasn’t related to a chipset defect or design issue. I also tried using a different webcam, but I experienced the same problem with a Microsoft LifeCam VX-5000 (USB webcam with built-in microphone) attached to the Vostro 1720, a Dell Inspiron 1501 laptop, and an ASUS-based desktop. Finally, I tried using a different video conferencing solution. Even with Roxio SightSpeed’s echo cancellation feature enabled, the customer experienced the echo problem.

After consulting both a Dell onsite technician and a Dell Premium Support technician, I finally discovered the problem. In Windows XP Pro SP3, if you configure the microphone or speaker level through the Control Panel Sounds and Audio Devices applet (using the Test Hardware wizard on the Voice tab), when you get to the third step—in which you can see both the active recording and active playback meters—you’ll experience progressively louder and louder echoing until you finally relent and click Cancel.

To solve the problem, start the Control Panel Sounds and Audio Devices applet and select the Audio tab to open XP’s volume control. (The default device in the Sound playbacksection should be your internal sound chipset—it was IDT Audio on the customer’s machine.) In the Sound playback section, click Volume. In the Master Volume box that opens, select Options and verify that Advanced Controls is enabled. Click the Advanced button, and ensure that 1 PC Speak Mute isn’t enabled. (If this setting is enabled, you won’t get any audio from the laptop’s built-in speakers.) Make sure that neither the Master Volume slider's Mute all check box nor the Wave slider's Mute check box are enabled. Set both the Master Volume’s slider and the Wave slider to about 80 percent. Close the Master Volume window.

Back on the Audio tab, click Volume in the Sound recordingsection. In the Recording Control dialog box that opens, select Options and verify that Advanced Controls is enabled. Click the Microphone slider's Advanced button, and make sure Mic Boost isn’t enabled. This setting isn’t enabled by default, but enabling it worsens the echo problem. Make sure that the slider's Select check box is enabled. Set the Internal Mic's slider to about 80 percent. Close the Advanced window, Recording Control window, and Sounds and Audio Devices applet.

Next, start Windows Live Messenger and select Tools, Audio and Video Setup. Run the simple wizard. Then, initiate a new video conference from your remote machine to the problematic machine. The user will immediately notice that the problem has disappeared.

Although this fix might be obvious to XP professionals, users can also benefit from the tip. I never have figured out why Windows Live Messenger’s tuning wizard didn’t override the faulty volume settings and provide echo-free video conferencing. I suspect that using XP’s Test Hardware wizard (mentioned previously) during an XP session causes other tuning wizards to subsequently tune improperly.