I’m using Audacity 2.0.5, and Windows Vista Home Premium (Service Pack 2).
For a long time I have been using Audacity to record directly from my computer’s Stereo Mix, allowing me to record any audio that’s playing from any program. It has usually worked flawlessly, but in the last two days a high-pitched background noise has appeared. This is not a white noise, but a tone, rather faint in the background, but my nice speakers definitely make it obvious at any decent volume.
When I click on Input Level (click to monitor), the first thing I notice is that, unlike in the past, the levels on that input monitor meter are not right at the bottom as they usually are - left is about -26, and right is about -33. This, I’m sure, is the sound that’s coming through when I record from the stereo mix.
I can also see that the (don’t know the technical term) blue line that represents the recorded sound is slightly above center on both sides of the recorded track, a little more so on the left.
I have made sure that software playthrough is turned off, and this sounds happens regardless of whether the power cord is plugged into my laptop.
I have included a screenshot showing both a few seconds of recorded noise, and also how the input monitor meter looks. I’m betting this noise is not created by Audacity, so what I’m really hoping is that y’all can help me identify what is creating it, even if it’s elsewhere in my computer.
Is the noise there if you import a known good song into Audacity and play it? Or only when you record?
Perhaps you have unmuted playback of an input that you don’t use.
Right-click over the speaker icon by the system clock, then choose “Playback Devices”. Right-click over the Realtek speakers then choose “Properties”. Then click the “Levels” tab. If you see sliders for inputs such as microphones, turn the sliders down or mute the output.
Click OK on that then choose the “Recording” tab. Right-click over each input device in turn (except stereo mix) then choose “Properties” and click the “Levels” tab. You should be able to mute the input there. This shouldn’t be necessary unless there is some sound leakage going on.
You should go to the Properties for stereo mix and look for any “Effects” or “Advanced tab” there may be, just in case there is a DC offset correction you can enable or an unwanted enhancement you can turn off.
Sometimes problems like this can be solved by uninstalling then reinstalling the sound device (even though the drivers appear not to have changed).
You can uninstall the sound device in Device Manager. You could then reboot and Windows would probably install a generic driver for the device or may even be able to find the correct driver. This is much less likely to work on XP or Vista than on Windows 7 or Windows 8, so the better method is to uninstall then go to the web site of your computer manufacturer then manually download and install the Vista drivers for your sound device.
In case some other change has caused the problem, you could also try going back to a previous System Restore point.
Sometimes too, backing up your data and reinstalling Windows may fix it. The older the Windows version, the more likely something like this will happen as Windows gets more clogged up with system changes. In the past I’ve fixed unexplained built-in sound card noise a couple of times on Windows XP by reinstalling Windows then reinstalling the sound device.
Noise & DC offset are almost always analog-hardware related.
[u]Total Recorder[/u] ($18 USD and up) can “capture” the streaming audio digitally using a “virtual soundcard/driver” to bypass the hardware. (There are a couple of other programs with similar features.)