http://www.wfmt.info/Musictherapyworld/modules/archive/stuff/papers/Wigram.pdf
Thesis submitted for the degree of Doctora of Philosophy, St. Georges Hospital Medical School London University
Anthony Lewis Wigram (author)
Abstract:
Vibroacoustic and vibrotactile devices that transmit sound as vibration to the body
have developed over the last 15 years, and have been reported anecdotally to
produce relaxation and reductions in muscle tone, blood pressure and heart rate.
Vibroacoustic (VA) therapy is used in clinical treatment and involves a stimulus that
is a combination of sedative music and pulsed, sinusoidal low frequency tones
between 20Hz and 70Hz, played through a bed or chair containing large speakers.
There is limited evidence to support the efficacy of VA therapy in the clinical
situations in which it is used. The studies in this thesis investigated the clinical effect
of VA therapy, and the effect of elements of the stimulus on non-clinical subjects.
A study on 10 multiply handicapped adults with high muscle tone and spasm
compared the effect of eight trials of VA therapy with a similar number of trials of
relaxing music. A significantly greater range of movement was recorded after VA
therapy than relaxing music. No significant difference was found in changes in
blood pressure or heart rate.
Comparing the effect of VA therapy with music and movement-based physiotherapy
(MMBP) and relaxing music alone on 27 subjects with high muscle tone and
spasticity revealed no significant difference in range of movement between VA
therapy and MMBP, but a significant difference comparing the combined results of
MMBP and VA therapy with relaxing music alone. Additional trials found significant
differences between VA therapy and music alone.
A study on non-clinical subjects (n=39), and a second study (n=52) measured
perceived location of bodily vibrations in response to sinusoidal tones between
20Hz and 70Hz through a VA bed. Reports indicated some that frequencies caused
sensations of resonant vibration consistently in the same places in the body.
A second study on non-clinical subjects (n=60) in three groups found that VA
therapy had a significantly greater effect in reducing arousal when compared with
relaxing music, and a control, and heart rate when VA therapy was compared with a
control. No significant differences were found between the groups in changes in
blood pressure.
A third study (n=60) found no significant differences between four groups when
evaluating the effect of varying rate of amplitude modulation of a 40Hz sinusoidal
tone and a constant tone.
These studies have clarified the efficacy of VA therapy as an intervention for clinical
populations, and the effect of the stimulus on normal subjects. Questions remain
about the nature of the stimulus that is used, and its effect on behaviour.
Keywords: vibroacoustic therapy, music therapy, sound therapy