How do ultrasonic devices built to scare away animals such as cats work? Do they mimic a high-pitched sound known to scare such animals, or do they scare them simply by their loudness? Perhaps it is just that the sound annoys the animals as much as it annoys me.
Lewis O鈥橲haughnessy, Salisbury, Wiltshire, UK
This article appeared in print under the headline 鈥淪caredy cats鈥�
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