UPDATE
A Thai woman who comes to our house daily to do house cleaning told my wife that the culprit is a guy who lives two houses from mine.
According to our domestic helper, he uses an electronic device to make the loud, shrill noises at dawn and in the afternoons. She advised my wife not to worry about it because the perpetrator has become public enemy number 1, with the perpetrator's wife being too embarrassed to face her neighbors whenever she goes shopping.