How about this?
And you can create your tone in Audacity ...
You can get it from audacity.sourceforge.net I made a 33Hz file, but it wouldn't let me upload it. I will leave instructions instead...Once in Audacity, click "Generate" then "Tone" then select "Sine" and set the tone to 33Hz and the duration to whatever you want. Click "File", "Export as WAV".
That should do it.