Characterization of the Forearm's bio-acoustical properties - a study on acoustic source localization on the human forearm as a potential human-machine interface
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Typ
Examensarbete för masterexamen
Program
Sound and vibration (MPSOV), MSc
Publicerad
2021
Författare
Brundin, Niklas
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Bio-acoustics have started to increase in popularity outside of the medical field, where
it has been used as a tool to determine bone health and provide hearing aids through
bone conduction. Over the last couple of years several projects have been conducted
utilizing bio-acoustical signals as an alternative to conventional human-machine interfaces
such as touchscreens and voice recognition.
This thesis investigates the possibilities of utilizing the bio-acoustical characteristics
of an individual’s forearm as a human-machine interface through acoustic localization
of self inflicted impacts. It also aims to analyze the bio-acoustical properties of the
forearm, how these properties are affected by muscle tension, and to verify if these are
universal properties which can be observed for multiple test subjects.
The results show that there are universal characteristics between several test subjects
and that there is a frequency region between 70 Hz and 350 Hz with low attenuation,
which is well suited for bio-acoustical measurements. This frequency region can be altered
by having the test subjects place their wrist in extension or flexion, which causes
the frequency region to shift by roughly 30%. It was also shown that the different impact
positions have unique time signatures and frequency spectras compared to each
other. The amplitude difference between the two sensors was also unique for the impact
locations and showcased a symmetrical pattern between the medial or lateral side.
The location specific amplitude differences only held true as long as impact located at
the middle of the forearm were excluded. The time difference between the two sensors
did not show the same symmetrical pattern as the amplitude difference, and can therefore
not be used on its own to determine the direction of arrival.
Beskrivning
Ämne/nyckelord
bio-acoustic, bio-vibration, bone conduction