19th May 2015
A few months ago my father installed some cat deterrents in our garden to deter the neighbours cats from defecating on the lawn. They are supposed to be ultra-sonic and therefore only audible to cats and are also supposed to only go off if an animal walks in front of them. In fact neither of these things are true. Due to their extreme loudness they are audible to some humans despite theoretically being of too high frequency for a human to hear. Furthermore weather conditions cause them to go off even in the absence of anyone/thing walking in front of them as I will document below.
Rain has a slight effect on the cat deterrents. Light or medium rain has no effect but heavy rain will cause them to go off occasionally.
Wind has a strong effect on the cat deterrents. Moderate or heavy wind will cause them to go off continuously without pause.
Sun has a moderate effect on the cat deterrents. It seems to make them more sensitive, multiplying the other effects. When it is bright sun they will usually go off at least once or twice a minute even if it's not windy.
For someone who has good enough ears to hear the cat deterrents the best situation is no wind and dim to medium light. Under such conditions the cat deterrents will only go off if an animal (or more commonly a human) walks in front of them.
The worst situation is Sunny. Under such circumstances the cat deterrents go off frequently and furthermore people who can't hear the cat deterrents are likely to open all doors and windows to "enjoy the lovely day" thus causing the inside of the house to be flooded with a constant bleeping sound of great persistence and annoyingness.
The author has been suffering from dizziness for about 8 months but has no particular reason to believe that this is caused by the cat deterrents. If this does turn out to be the cause then I will add this here.