As I mentioned in a previous post, I have successfully installed Windows 7 Ultimate as a guest operating system under VirtualBox – complete with USB drivers.

The installation was painless and easy, but when I started Windows, it kept reporting that “No Audio Device is Installed”. Audio was enabled for this guest machine in VirtualBox, but nothing was working.

In the end, I decided to try installing the drivers manually. The nice thing about VirtualBox is that it presents either a SoundBlaster 16 or a Realtek AC’97 card to the guest. Here’s how I fixed the problem:

• Go to the settings of the virtual machine and click on the Audio tab.
• Make sure audio is enabled, and set the Host Audio Driver to PulseAudio, set the Audio Controller to ICH AC’97
• If you have Internet access on the virtual machine, then start the machine now, and download the drivers from the link that follows. If you don’t have Internet access on the virtual machine, then download the drivers and place them in a shared folder for the guest to access. The link is http://www.realtek.com.tw/downloads/ and click on the AC’97 Audio Codecs (Software) link. Accept the agreement, and download the appropriate version for your guest virtual machine – I needed the Vista/Windows 7 drivers.
• Install the drivers to your guest machine, by extracting the zip file to a folder on the guest hard drive. You may have to ask Windows to search for the driver, then click on Have Disk and browse to the location of the files.
• Restart your virtual machine and sound should be working.

You can try different host audio drivers if you wish. I got the best results with PulseAudio, but others will work as well. They just made the sound a bit choppy to me.

VirtualBox Audio Settings