generator is usually placed entirely within the isolation box the sound generator is preferably designed to deliver a constant pressure against the skin of from 0 001 pa to 10 pa any means for capturing sound may be utilized in the system of the present invention for example a gras 40ae 0 5 inch microphone from oros france is suitable the microphone may have a preamplifier such as a gras 26ca 0 5 inch preamplifier from oros france the means for capturing sound should be sensitive to a signal with a frequency from 0 5 hz to 22000 hz in one embodiment the means for capturing sound is connected to a computer for example the means for capturing sound may be a microphone that utilizes a sound card for example a duo usb 24 bits 96 khz sound card from m audio that is useful for connection to a computer sound recorder software such as praat version 4 2 19 may be useful for capturing sounds and evaluating them on the computer the system according to the present invention may be better understood with reference to the figures in the embodiment seen in fig1 and fig2 the system 10 includes a motor 2 a and guiding device 2 the system may include a support 1 e g a wooden support for resting the portion of skin to be tested in this embodiment a metal rod 3 is connected to the motor 2 a and guiding device 2 at the distal end of the rod 3 are attachment means 7 for sound generator 6 in the example illustrated attachment means 7 are springs and the sound generator 6 is a card means for capturing sound 8 e g a microphone can be attached to rod 3 acoustic isolation box 4.