In episode #47 of 'Ask Geoff and Lauren' we answer a question from Jennifer about treating a wolf tone on her double bass. A wolf tone is an artificial overtone which occurs at the frequency your double bass naturally resonates. They are very common and the bad news is that a that a wolf tone can sound terrible but the good news is that they are easily treated.
We discuss how we have handled a wolf tone on our instruments and how you can go about it.
In the video we discuss Wolf Tone Eliminators. They are a cheap and effective way to combat wolf tones and here's a great article on Gollihur Music if you want to know more about them.