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D. Cotoros et al.
birds chirping) but they may also produce negative effects like hearing troubles,
circulatory problems, balance loss, and many other symptoms, subjective or not [1].
The present study was concerned with the fact that most lethal accidents at work
places are due to falls as a result of balance loss, which may often happen during
exposure to certain types of sounds [2].
Previous studies focused upon the influence of low frequency sounds (frequency
sounds below 0.5 kHz) upon laboratory mice [3] but also of ultrasonic sounds (high
frequency over 20 kHz) on people with various age [4] or gender [5], proving that
there is no doubt that low and high frequency sounds will affect to a certain extent the
posture control of the investigated subjects. There are also authors who found there
are no significant changes in postural stability during quiet standing if subjected to
auditory stimuli [6].
There are different opinions on the subject mainly because there are so many physical parameters of sound that may influence at a certain extent human postural balance
(frequency, intensity, type, duration, location, etc.), so things are insufficiently
researched.
Our team focused not only upon changing frequency but also on producing sounds
coming unexpectedly from different locations because the intermittence of sound
may be a stressful factor affecting suddenly the postural balance.
2 Materials and Methods
In order to perform the tests, a number of 48 students (37 females and 11 males)
were involved. They are young with ages between 20 and 26 and declared they had
no previous health issues; also their age offered some assurance that hearing was
not yet affected by aging and normal hearing frequencies would not be a problem.
Their height is between 1.57 and 1.93 m and their weight between 46 and 87 kg.
The subjects were carefully briefed at a certain extent about their contribution. The
experiments were performed within the Advanced Mechatronic System Laboratory
of Transilvania University Research Center. The building is situated in a quiet area
with no traffic sounds or other interfering noises which might affect the results of our
experiment. The students were called at different times, one by one and remained in
the laboratory after the experiment so that communication was avoided and allowed
to surprise them with the sounds.
For producing sounds of variable intensity and frequency, a free sound generator
software on mobile phone was used and also a small speaker in order to be able to
change rapidly the sound location without catching the subject’s attention. The software offers the possibility of producing sine wave sounds (basic isolated sound with
no harmonic or inharmonic sounds), square wave sounds (contains odd harmonics
besides the basic sound), sawtooth wave sounds (contains all harmonics), or triangle
wave sounds (fundamental frequencies plus odd harmonics) with different intensities
and frequencies [7].
D. Cotoros et al.
birds chirping) but they may also produce negative effects like hearing troubles,
circulatory problems, balance loss, and many other symptoms, subjective or not [1].
The present study was concerned with the fact that most lethal accidents at work
places are due to falls as a result of balance loss, which may often happen during
exposure to certain types of sounds [2].
Previous studies focused upon the influence of low frequency sounds (frequency
sounds below 0.5 kHz) upon laboratory mice [3] but also of ultrasonic sounds (high
frequency over 20 kHz) on people with various age [4] or gender [5], proving that
there is no doubt that low and high frequency sounds will affect to a certain extent the
posture control of the investigated subjects. There are also authors who found there
are no significant changes in postural stability during quiet standing if subjected to
auditory stimuli [6].
There are different opinions on the subject mainly because there are so many physical parameters of sound that may influence at a certain extent human postural balance
(frequency, intensity, type, duration, location, etc.), so things are insufficiently
researched.
Our team focused not only upon changing frequency but also on producing sounds
coming unexpectedly from different locations because the intermittence of sound
may be a stressful factor affecting suddenly the postural balance.
2 Materials and Methods
In order to perform the tests, a number of 48 students (37 females and 11 males)
were involved. They are young with ages between 20 and 26 and declared they had
no previous health issues; also their age offered some assurance that hearing was
not yet affected by aging and normal hearing frequencies would not be a problem.
Their height is between 1.57 and 1.93 m and their weight between 46 and 87 kg.
The subjects were carefully briefed at a certain extent about their contribution. The
experiments were performed within the Advanced Mechatronic System Laboratory
of Transilvania University Research Center. The building is situated in a quiet area
with no traffic sounds or other interfering noises which might affect the results of our
experiment. The students were called at different times, one by one and remained in
the laboratory after the experiment so that communication was avoided and allowed
to surprise them with the sounds.
For producing sounds of variable intensity and frequency, a free sound generator
software on mobile phone was used and also a small speaker in order to be able to
change rapidly the sound location without catching the subject’s attention. The software offers the possibility of producing sine wave sounds (basic isolated sound with
no harmonic or inharmonic sounds), square wave sounds (contains odd harmonics
besides the basic sound), sawtooth wave sounds (contains all harmonics), or triangle
wave sounds (fundamental frequencies plus odd harmonics) with different intensities
and frequencies [7].