In
order to understand the essence of the question, let us repeat once again the
statements of authoritative scientists about these two types of sounds made by
the bees:
The
signals emitted by the wings of bees are in the range of about 70–250 Hz. And this signals, emitted by the wings, have
peculiarities, associated with the biological structure of the wings. Let's
refer to the classic book of Langstrott - "The Bee and the Hive" ...
"The musculature of
the honeybee wing consists of indirect muscles that are not connected with the
base of the wing and the rectus muscles, connected to its base. Indirect muscles
play a major role during flight. Their volume is very large, and they fill almost all chest cavity. One type of
indirect muscles, is attached from the
inside to the skeleton of the thoracic region in the dorsal-ventral direction.
These are vertical muscles. Other type, is located in the longitudinal
direction. When contraction of the vertical muscles, the mesonotum is lowered,
flattened, presses against the base of the wing, and the wing rises upward.
With subsequent relaxation of vertical muscles and contraction of the
longitudinal muscles, wings descend, and the mesonotum rises and becomes convex
again. Change of contractions of the vertical and longitudinal muscles occurs
very quickly: the frequency of wing strokes can be 200–250 per second...
...These
high-frequency muscles constitute the most active of all contractile tissues,
that have ever appeared in animals, in the process of evolution. Nervous
centers do not send motor impulses to the muscles of the wings in such a high
rhythm. This rhythm exceeds the rate of electrical processes on the surface of
the cell membrane. The muscles of the wing come to the state of contractions by
themselves, under the action of stretching. They work on the principle of a
resonating system, the frequency of their compactions is determined by the
degree of their tension..."
Here
is the phrase, which is so important to us! ... "The resonant system"
... This means, that we get the classical oscillatory mechanism, operating
according to the classical laws of physics. And this is the main characteristic
of the signals, generated by the wings - aeration, ventilation, flight.
That
is why, signals of the wings except the main tone, create an overtones multiple
to the main tone - x2, x3 ... and \ 2, \ 3...
and all subsequent .....
What
do we know about the sounds, created by the vibration of the bee's thorax ...
"... The process of functioning of
the muscles of indirect action, when bees make sounds , differs significantly from the process of functioning of these muscles,
during the flight ... (Esch and Goller, 1991; King et al., 1996) It is believed that during the production of
( vibro-acoustical) signal, the uneven shortening of antagonistic muscles of
indirect action and the associated closure of the slit of scutellum, which cause the change of vibration characteristics of bee's
thorax in such a way, that the "flight system" of the bee vibrates at
a higher frequency (King et al., 1996). ... . "
Exactly this was fixated, in the process of our research! Vibro-acoustical
signals, generated by the bee thorax, do not have the correct classical
harmonics around the main signal. Rather, the true signals emitted by the bees,
are the signal of the fundamental frequency ( main tone) and the “wings”. This "wings" can always be visible
on diagram with one and the same parameters — the basic tone, +1\2 of main tone, + 2\2, + 3\2 of main tone and so on .... and
-1\2 of main tone, -2\2, -3\2 of
main tone and so on .... for each subsequent.
These characteristics of the two
signals allow a person, who understands their nature, to see difference between
real communicational signal of the bee and ventilation, in case of their simultaneous appearance on
the screen. After all, the range of bees' signals is very narrow, and the
imposition of signals and their "harmonics" occurs constantly. (In
this case, we will call the “harmonics”, for simplicity, both types of
additional signals appearing around the main signal.). Let's have a look at examples....
The
first situation is quite common in the summer time, the second is more
characteristic for winter and for autumn.
The
third combination, is the most unpleasant of all. Such a picture arises, if the
microphone ( wired or internal) is not in the depth of the hive, but on the
porch of the hive, when recording or measuring.
At the same time there is a strong honey collection, and the family of
bees is also strong enough. A lot of bees arrive to the porch at the same time,
and in the entrance there are many bees ventilating the hive. In this case, the
signals of work are very poorly distinguishable. This situation is the error of
the person, who is taking the measurements, as the work signals are completely
suppressed, and diagnosis will be very far from reality.
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