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MMG signals - summary

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  • MMG signals - summary

    Dear All,

    I am very thankful for receiving so many responses to my enquiry
    regarding MMG signals. Special thanks are to Frank B, Joel T Cramer, Edmund
    Cramp and Kyle Ebersole. A summary of the answers follows bellow:

    “Indeed one can use microphones or small acclerometers to recording vmg etc.
    Dytran has miniature acclerometers but they are quite expensive, and we have
    not yet got good data w/ that (but others have?). VTI Hamlin has quite
    affordable accelerometers (around $50 if I remember correctly). These are in
    forms of chips (e.g. SCA 610 series) so one has to glue them onto small
    plastic bended pieces in order to get them oriented in the right direction.
    With inbuilt amplifier they are very simple to use. Small electret
    microphones can also be used (around a couple of euro a piece) As an
    experiment we plugged a microphone into an ordinary stethoscope (cut off
    part of the "tube" and inserted the microphone into the tube). Preferable
    one should make a somewhat lighter "cup" for collecting the sound (amplifies
    the air pressure that reaches the microphone)”

    “Different nomenclature has been used to describe the mechanomyographic
    signal (i.e., acoustic myography, vibromyography, sound myography, and
    mechanomyography). We have chosen to use the term mechanomyography (MMG) in
    our studies to be consistent
    with the suggestion of Orizio, C. (1993). Muscle sound: bases for the
    introduction of mechanomyographic signal in muscle studies. Crit Rev Biomed
    Eng, 21: 201-243. As you may already know, Dr. Orizio's review is a very
    helpful source of information on a number of topics regarding MMG. Also,
    the review by Stokes, M.J. (1993). Acoustic myography: applications and
    considerations in measuring muscle performance. Isokin
    Exer Sci, 3: 4-15 is another helpful source. I am not familiar with any
    literature indicating that the nomenclature is a function of the type of
    sensor used to record the signal. Dr. Claudio Orizio's review, however,
    briefly discusses the different terminologies used and provides a
    justification for the use of "mechanomyography."

    There are two basic classifications of MMG signal acquisition units: 1.
    piezoelectric crystal contact sensors, and 2. accelerometers. We use
    Hewlett Packard (HP) 21050A piezoelectric crystal contact sensors in our
    laboratory interfaced through a BIOPAC acquisition unit and A/D converter.
    Again, sensor differences and justifications for using either are discussed
    to great extent in Dr. Orizio's review. In addition, Dr. Watakabe has
    published several recent papers on the use of different MMG sensors. The
    following reference is the most recent publication of Watakabe et al. that I
    am aware of on this topic. Further references are included in this paper.
    Watakabe, M., Mita, K., Akataki, K., and Itoh, Y. (2001). Mechanical
    behaviour of condensor microphone in mechanomyography. Medical &
    Biological Engineering & Computing, 39: 195-201.”

    “Since the EMG and AMG signal bandwidths are relatively similar, I would
    expect that almost any modern EMG system could be used. I am certain our
    own system (Motion Labs MA-300 -
    would work”

    “As for the recording device, most are either using an accelerometer OR a
    heart sound/pulse contact sensor made by Philips Medical Systems. Little is
    know on the potential differences between the devices, but the results tend
    to be the same...or at least interpretation of the results. Dan Barry
    published a paper on using the MMG signal as a prosthetic control (Arch Phy
    Med Rehabil 67:267-269, 1986)”


    Adriano de Oliveira Andrade , PhD student
    University of Reading
    Department of Cybernetics
    Pepper Lane
    Reading RG6 6AY, UK
    tel: +44(0)118 378 7111
    fax: +44(0)118 378 8220

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