"All that science has done is given man a dozen new sets of eyes --- and that makes it a great deal worse. For instance, there's the germ (if it is a germ) that is always swimming just outside the edge of the brightly lighted field of the microscope, that eludes even the electronic microscope. There's the planet (if it is a planet and not some vast black sentient thing poised above the earth) that is seen out of the corner of the telescope's eye. There's the radar echo that doesn't  seem to be coming quite from the moon, but somewhere else. There are the atomic glows that aren't just what the nuclear physicist expected. There's the buried thought that the psychologist can never quite reach, not even when he employs the hypno-analytic technique which can dredge up memories of events that occurred when the patient was six months old. (And is the buried thought a human thought, or a demon's?)....

- Fritz Leiber, from Weird Tales, 1946.

Thanks Fritz. Likewise, there's this underwater frequency that scientists can't quite place.