If you would license the SVG file under the same license of Audacity (GPL 2 or later) you would be on the safe side. I do not think, that they own a trademark for it. There should be no problem, if you use this SVG icon as application icon. Please add the copyright information into the SVG file.
If you would license the SVG file under the same license of Audacity (GPL 2 or later) you would be on the safe side. I do not think, that they own a trademark for it. There should be no problem, if you use this SVG icon as application icon. Please add the copyright information into the SVG file.