Have you ever been startled by hearing sounds that have nothing to do with the spot you are in and which may unsettle you as faulty hearing or in some cases cause a scare by appearing to be paranormal or portents of the Apocalypse. Five years ago an open forum Reddit contributor on Internet reported that “This past evening when out for a walk in the neighbourhood I heard what I thought was someone having a party or their TV up way too loud. I could hear an announcer counting down to the start of a drag race, and then the sound of motorcycle engines racing down the street. I attempted to locate the sound but if I walked outside of a certain radius of several hundred feet it wasn’t as clear, and couldn’t locate where it was coming from. Today I found out that there was drag event at the local drag strip that night that is about 6 miles as the crow flies from where I was”. During the First World War, there was a case where people, miles away from the Battle of Gallipoli heard the firing of naval guns as the British tried to maintain a foothold on the peninsula.

Hearing sounds created far out of range of human hearing is neither a portent of doom nor something from the ‘twilight zone’. It is merely a perfectly explainable natural phenomenon known as ‘Audio Atmospheric Ducting’ caused, when sound is reflected by an inversion layer in the atmosphere (or in water) and can be heard across unbelievably long distances, especially in the presence of thick layers of cloud cover.

I remember hearing the roaring of lions in the Lahore Zoo and the pealing of the bell in the Catholic Cathedral on Lawrence Road, while flying kites on the ‘mumti’ of our ancestral home, deep within the walled city of Lahore. Then there was the oft heard sound of steam locomotives from the yard at the Lahore Railway Station, all the way at our home on Queen’s Road and in the northernmost corner of Islamabad, one frequently hears the revving of aircraft engines at the Airport, on a cloud covered day – a sound so clear that it appears to be coming from somewhere, in the next Sector.

My greatest experience with ‘ducting’ was however, during the years when I had got over myths and immersed myself into a career that gave me ample opportunities for outdoor adventure. I was spending a few days in a canal rest house in a semi-hilly area of Northern Punjab, when the local caretaker cum ‘chowkidar’ asked me, if I had been disturbed by a hooting sound associated with the ‘water mill’ used to grind corn. I said that I had and now that he had mentioned it, would like to visit one, which by the sound of it, appeared to be close by. I was surprised, when told that there was no such facility within miles of where I was staying and that the sound was the wailing of a ‘banshee’ that roamed the forest, preying on unwary humans. Sensing a catch and having read about atmospheric effects on sound, I asked him how far was the closest ‘pun chakki’ in the area and whether the ‘churail’ had been heard on clear sunny days. I was told that a ‘chakki’ was located approximately five miles up the road and on bright sunny days, the demon rested. No amount of explaining that the ‘banshee’ was none other than ‘ducting’ created by clouds, could convince the man that he was wrong.

A roaring or booming sound coming from the sky caused a ripple of panic in many US and European cities around 2013. Meteorologists explained the unsettling event, as a manifestation of the ducting effect. The Yearbook of Facts, published in 1851 and the journal of the The British Meteorological Society, 1864 also reported similar occurrences.

Radio users know that atmospheric layers have properties that can reflect or refract transmissions depending on the type of frequency being used. These properties are used by commercial radios (not the FM Networks) to transmit long distances using the Ionospheric Layer. Users of radio communication often use the reflection and refraction effect to gain longer ranges or communicate with spots otherwise inaccessible by conventional wireless.

Reports of humans communicating across vast distances or sounds coming from the sky are as old as history itself. These have been recorded in ancient texts, epics and mythologies. Modern science has proved that there may be a grain of truth in these narratives, for the human race has yet to understand the ‘true nature of nature itself’.

The writer is a historian.