Human Factor Balance Under the Influence …
301
Fig. 4 Stability area for sine wave coming from one side
show very clearly higher values of the forces occurring at the exact moment when
the sound was released (second 12 and second 27) proving the physiological reaction
due to the small shock of surprise by the sudden noise. (Fig. 5)
Also it can be noticed that the reaction to the repeated sound was not so powerful
as to the initial sound because the subject was already prepared at a certain extent
that some sound may occur and stayed focused.
Similar reactions were obtained for triangle wave and square wave sounds, the
sway was a little higher and also the values for the force Fz.
A special attention was paid to the sawtooth wave sound, as it includes all
harmonics besides the fundamental frequency. This type of sound waves is the most
disturbing one, it happens, for example, during explosions and earthquakes, so as it
was expected, the reactions were proportional.
Some of the most representative results are presented in Figs. 6, 7 and 8.
The “protection” instinct is very obvious in this diagram; the stability area is
spread along the lateral axis Oy and the sway reaches 0.064 m.
Time (seconds)
0
5
10
15
20
25
30
524
528
532
536
540
544
548
552
556
560
Fz [N]
Fig. 5 Variation of reaction force Fz during the sine wave experiment
301
Fig. 4 Stability area for sine wave coming from one side
show very clearly higher values of the forces occurring at the exact moment when
the sound was released (second 12 and second 27) proving the physiological reaction
due to the small shock of surprise by the sudden noise. (Fig. 5)
Also it can be noticed that the reaction to the repeated sound was not so powerful
as to the initial sound because the subject was already prepared at a certain extent
that some sound may occur and stayed focused.
Similar reactions were obtained for triangle wave and square wave sounds, the
sway was a little higher and also the values for the force Fz.
A special attention was paid to the sawtooth wave sound, as it includes all
harmonics besides the fundamental frequency. This type of sound waves is the most
disturbing one, it happens, for example, during explosions and earthquakes, so as it
was expected, the reactions were proportional.
Some of the most representative results are presented in Figs. 6, 7 and 8.
The “protection” instinct is very obvious in this diagram; the stability area is
spread along the lateral axis Oy and the sway reaches 0.064 m.
Time (seconds)
0
5
10
15
20
25
30
524
528
532
536
540
544
548
552
556
560
Fz [N]
Fig. 5 Variation of reaction force Fz during the sine wave experiment