Posted: 27/06/2013 at 09:52
Not an easy one this & I think a few of us have been there...
How well do / did you get on with these neighbours before? If things were reasonably amicable I would try my best to avoid making the whole thing escalate into an unpleasant battle. If they were bad - well, things could get a whole lot worse..
'Tactful' ways that might work include a 'noisy' (see Fairygirl above) water feature - if it makes the lady run to the loo every 20mins that might help. Annoying (yet somehow acceptable) noises such as irritating windchimes might encourage them to move away from the boundary.
After that - try a bit of gentle escalation - when you know they're there - start having a loudish conversation yourself so they know how much the voices carry. Then perhaps a lawn mower when they're outside. In graduation terms you could then go strimmer, chain saw and leaf blower.
What about an oscillating sprinkler that 'accidentally' sends a few drops over the fence???
If they don't move away after all that, your only option might be to move your sitting area.
Problem is - once you're tuned in to listening for her voice / laugh you'll cringe every time you hear it & magnify the volume in your head. Try and keep a sense of perspective - war with your neighbours is a real recipe for unhappiness.
Best of luck.