whatever it is,i heard something similar, not the high pitched trumpet like noise but the low pitched like rumble noise i guess more like a trombone. whatever it is its creepy, and if you ever happen to hear it for yourself it gives you a very uncomfortable feeling.
infra-sound!
http://en.wikipedia.org/wiki/Infrasound
Human reactions
20 Hz is considered the normal low-frequency limit of human hearing. When pure sine waves are reproduced under ideal conditions and at very high volume, a human listener will be able to identify tones as low as 12 Hz.[32] Below 10 Hz it is possible to perceive the single cycles of the sound, along with a sensation of pressure at the eardrums.
The dynamic range of the auditory system decreases with decreasing frequency. This compression can be seen in the equal-loudness-level contours, and it implies that a slight increase in level can change the perceived loudness from barely audible, to loud. Combined with the natural spread in thresholds within a population, it may have the effect that a very low-frequency sound which is inaudible to some people may be loud to others.
One study has suggested that infrasound may cause feelings of awe or fear in humans. It also was suggested that since it is not consciously perceived, it may make people feel vaguely that odd or supernatural events are taking place.[33]