A pair of concrete sound mirrors enable people to talk to each other across a small park at Kew in west London.
If you fancy a sound mirror of your own (or two, as I suppose one wouldn’t be much use on its own), then see the Parabolic Reflectors section of the “Acoustic and Play” catalogue from the German manufacturer, Richter Spielgeräte. The same company supplied the Royal Military Canal sound mirrors.
The Richter Spielgeräte mirrors are 1.8 m high and 1.4 m in diameter, and cast as a single piece of steel-reinforced vibrated concrete weighing about 300 kg. They are designed to be positioned 30 to 40 m apart.
The park is next to the sewage works (the location is nicer than it sounds!), and accessible from the riverside footpath. Buses to Kew Retail Park stop not far away, or it’s a pleasant walk alongside the river to Kew Bridge.
Thanks to Erin Deighton for letting me know about the mirrors; she says they are “great for kids”.