The Hum HUM vertical component, By Dr Chris Barnes, Bangor Scientific and Educational
Consultants, Bangor, Gwynedd, Wales, UK E-MAIL manager@bsec-wales.co.uk
Introduction
The HUM is enigmatic and anomalous sound (possibly infrasonic) heard
throughout the world. As far as I am aware researchers have been unable to
source the HUM or even point effectively towards its direction.
It is known however, that the HUM is perceived louder in houses and
stationary vehicles. This has often been put down to the fact that these
enclosures provide masking from external noise.
An alternative proposal would be that the HUM has a strong vertical
component which forces these structures and /or the air column within into
vertical pressure oscillation.
Some simple experiments have been performed which would strongly appear
to confirm this hypothesis.
Experimental work
1. Based on the notion that the HUM may have acoustic or vibration
components in yet not withstanding the possibility of
individual; sensitisation to the HUM by other force fields, an experiment was
devised to try to directionally amplify the HUM.
The apparatus used was essentially very primitive but highly effective.
The lid of garden refuse incinerator was employed as a sort of giant ear
trumpet!
Placing the narrow end of the lid to the ear would be expected to cause
a focussing effect for sound waves in the vicinity of the user.
Whilst experiencing a particularly strong episode of the HUM on the
evening of Tuesday July 17th at circa 2300 hours and the morning of
July 18th at 0800 hours the author placed the narrow end of the lid
first to his left ear and then to his right and proceeded to walk in a tight
360 degree turn. Then with the lid to
his right ear the author turned so this ear faced the ground. The experiment
was performed in a small downstairs room with all sound sources in the house
switched off.
The lid was also subsequently placed on the floor broadside down and the
author placed his right ear about 1 cm above the narrow end.
2. Standing waves
If the Hum component was
horizontal it should be possible to detect standing waves
by walking to various locations in large rooms. Slight nodes and
antinodes could be detected by the unaided ear on the ground floor of the author's premises, corresponding to a
room resonance of about 28 Hz but not
the second floor.
Results
Placing the lid to left ear made no impact on the HUM level whatsoever.
No directivity in the HUM could be discerned. Placing the lid on the right ear
actually reduced the HUM level slightly whilst standing normally and rotating,
yet sounds of other kinds such as vehicular and people noise outside the house
could be heard clearly amplified with expected directivity. Only in the
downward direction the HUM level was noted to increase significantly.
With the lid placed on the floor as described above a very significant
increase in HUM level could be discerned but only with the author’s right ear
about 1 cm above the open end. Clearly
the air column above the lid needed to move to and fro.
Discussion and Conclusions
These simple experiments prove that the HUM has a significant vertical
component.
There may be some horizontal component at ground floor level. These finding could be explained if the
Hum was diffracted into premises at
steep angles from above or below and/or if the Hum has more than one component which has proved
to be a previous pre-requisite. Given the height of the house and the fact that
it has a chimney
a vertical Helmoltz
resonance as low as 9.4 Hz may be possible.