A Mysterious unexplained spooky Sound

We know that unexplained sounds have been reported Worldwide. But we didn't expected to heard one.
it was the gloom when we suddenly heard this strange sound. We didn't know where it comes from, we were thinking it was bad electrical wiring, but it wasn't. It was even more strange because this happened on several consecutive days at the same time. It was very mysteriously. Tina felt like it was already Halloween.