Transferred VHS audio looping from dull to sharp
 

I recently transferred footage from a VHS tape, but when I played the footage back, the audio went from sharp to dull then sharp to dull throughout the entire length.
Is there any way this can be fixed? Is there any software for Windows that could fix this problem?

Thanks.....

audacity, it's free, many filters available, noise reduction equalizers etc..

I have attached a clip of the audio I need to fix.
 

I have attached a clip of the audio I need to fix.
You can hear quite easily the problem with the audio fluctuating.
I looked at Audacity, but can't really figure what to do.