strange rushing sound heard at night

I used the search function, but didn't find anything that closely resembled my experience, hence this thread. Last night for a couple of hours I heard a high pitched rushing noise outdoors. The air was still, so it wasn't simply wind. It was far too high in pitch to be any sort of normal aircraft, and in any case it came from the same direction (North) without apparent change, and not, so far as I could discern, from a high sky angle. The intensity of the sound varied considerably, and irregularly, over a matter of several minutes, or longer. It was quite loud at times. I thought of water or gas escaping from a broken pipe, but I found no evidence that this had occurred. Checked the emergency radio, fire and police channels, found nothing. Due to the apparent distance, and the (sometimes) loudness of the sound, it would have had to have been a major break, causing considerably commotion. I first heard this sound at about 11:15 p.m., continuing until at least 1:20 am, when I fell asleep. By daylight the sound was gone. I looked with binoculars at the hilly, sparsely populated land to the North, but saw no sign of anything unusual. I doubt that a solution to this mystery is possible, given the facts I have, but I thought it might be worth mentioning, in case someone else had had a similar experience, at some time. Its unlikely that anyone here would have been within earshot of this particular incident, but I am located at the Northern end of the San Francisco Bay Area. Ross

Is there a motorway near by? You would be suprised at the noise a heavy goods vehicle makes when travelling at speed.

If your far enough away and you can't hear the engine noise you will hear the tyres resonating against the road. It sounds like a high pitched whine, rising and lowering in volume. It used to scare me when I was a kid at my Grandmothers. She lived near a busy motorway and you could hear it in the middle of the night when there was barely any traffic.

Other than that could it be aggricultural machinery? I know farms near me often harvest all night long. When its calm and quiet at night the sound travels for miles.

Thank you, Grifter 81 for your suggestions. It's always a good idea to check these odd experiences against sensible possibilities. I live quite near California State Highway 12. I often hear noise from its traffic. It comes from the Southwest, in the form of a dull, low pitched roar. I doubt that this is what I heard, since it was a much higher pitched hissing or rushing sound, and from the North. There are no substantial roads to the North. There are vineyards in that direction, and not very far off. This is the harvest season, but it must be done by hand. I checked for any road repair projects that might have produced this unusual noise; none found. I listened last night to see if there would be a repeat of the strange sound; nothing heard. Conditions were similar to yesterday; cool, still air, favorable for carrying sounds. The odd sound seems to have been limited to just a couple of hours on one day, which seems to make it even more puzzling. Ross

I am no where near where you are but, On the night of Oct 31 @ around 4:00am I had a similar event happen. For me it sounded like a cross between a snowplough driving down the road with the plow down[speeding] and a gurgling kind of sound like a boat motor makes. It was such an odd noise and extremely loud it made me jump out of bed in a hurry. Since my windows are not far from the bed I opened the curtains to find nothing, no cars/trucks absolute silence outside. I have never heard a sound like that before and I have lived here for almost 10yrs.

I live near a paper factory, and sometimes we get this very loud and high pitched rushing sound that is caused by steam escaping. I think some of the machines let off a lot of steam at a certain time of the day or they just vent the steam more at certain times. Anyway, when they are doing this, it sounds really loud and can be heard all over town from miles away. I heard it even inside my house. It must be very loud to be near the mill when they do this, because it is so loud even miles away. It sounds like a high pitched rushing sound like that, and kind of sounds like it overhead but it isn't. It just just how the sound echos. The first time I heard the sound I thought something terrible had happened over at the mill, but I am more used to it now. They don't vent steam like that all the time, so I don't hear it so loud all the time. Usually they do it on a clear day. If I had ever heard that sound on a cloudy or stormy day, I'd think a tornado was coming.

Is there a motorway near by? You would be suprised at the noise a heavy goods vehicle makes when travelling at speed.

Yes this is exactly right! I live about 80 feet in front of a overpass a very populated four lane highway. To the front of my house is a railroad about 90 feet in front of the house. You would think a person would go crazy at night with all the ridiculous noises and let me tell you I have heard everything from tire blowouts to semi Jake breaks automobiles make very very weird sounds. Strangely enough I am use to all of that its the dead silence that freaks me out the constant hum I hear in my inner ear.

I've heard it! I'm in So Cal (Los Angeles County)

See my posts over here, it's already being discussed

www.abovetopsecret.com...

www.abovetopsecret.com...

Yes, I've seen those other threads. It isn't altogether clear if all these strange sounds are part of a single phenomenon, or not. Many seem to be low pitched sounds-- rumbling, roaring, or grinding, with a high sky angle, so as to pretty clearly indicate that they come from the air. The sound I heard was higher in pitch and was either at a very low sky angle, or actually on the ground. I may have simply heard the same source of sound under different conditions. I recall that one witness at first described a roaring sound, then spoke of mechanical grinding sounds, interspersed with short bursts of what sounded like escaping steam. This very last is similar to what I heard, except that mine was continuous. Another report compared the sound to the intermittent dragging of stone blocks, which might fall somewhere between the pitch of roaring and hissing. Most of these sounds are similar to the so called 'white noise', which is made up of a wide range of frequencies, rather than a narrow range, as in musical notes, or pure tones. This is the sound one hears on an FM radio, in between the broadcasting stations. When white noise is biased toward a particular range of frequencies it is called 'pink noise'. With the bass emphasized, there will be a rumbling or roaring, if treble predominates, there will be a rushing or hissing sound. The speed and direction of motion of the source of sound, relative to the observer, would have a biasing effect on the pitch, via the doppler shift. Higher pitch on approach, lower when moving away, and the greater the speed in either direction, the higher, and lower, respectively. Ross