Insect sound

Observation - Insect sound. Description: This observation may be of interest to you if the creature concerned is identified as either something unusual or one outside its usual range. Throughout July last year (2010), whenever the sun was shining I heard a strange sound coming from bushes in

This observation may be of interest to you if the creature concerned is identified as either something unusual or one outside its usual range.

Throughout July last year (2010), whenever the sun was shining I heard a strange sound coming from bushes in our garden boundary, obviously from some insect. It was a very, very high-pitched squeak lasting 2-3 seconds with a 1 second pause between bursts. Either there were several of them or it could throw its voice, as I seemed to hear it from other places as well. Whenever the sun went in it went quiet. It was not rasping or ticking, but a pure squeak, occasionally starting with a slight stammer “ta-ta-tee”. It carried so that I could clearly hear it from the other side of the garden 60 feet away but was so high-pitched that my husband could not hear it at all. However he recorded it digitally, then transferred it to a reel-to-reel recorder to slow it down and reduce it by an octave. The first attempt didn’t work as it was obviously outside the frequency range of the recorder, but then he put it on a professional machine, and could then hear it. However it was still very high-pitched, and sounded like a smooth whine or whistle, going up in pitch slightly at the end. The best description of the sound that I can think of is like the whine that some TVs used to make.
August was cloudy and breezy and we heard it no more, and it hasn’t been there this year. I’ve heard grasshoppers and crickets, but never anything like that before.

Our garden is on the northern slopes of a hill in Church Stretton, South Shropshire, about 800 ft up, and on clay soil, if that is of any help. The front garden where the insect was faces west and gets hot in the summer afternoons.

Any ideas?