minimum limit indicators 86 may be used to show the spread of the clinical measurements a default setting for each metric or user entered display settings 72 may specify how this spread is calculated such as by range standard deviation standard error or inter quartile range of the clinical measurements the absolute sound pressure level in decibels db spl of a subject 39 s voice provides a useful clinical metric to obtain this measurement the response of the measurement system must be calibrated with respect to a sound source of known intensity one embodiment of the present invention includes a subsystem for sound pressure level calibration a dataflow diagram for one embodiment of this subsystem is shown in fig3 a recording unit 27 records digital samples 4 of sound produced by a subject or a calibration sound source measurement unit 29 computes the peak sound intensity 30 this peak intensity is the maximum intensity for the entire sound sample where the intensity is the mean square amplitude and is computed over successive intervals of duration between 0 01 an 1 0 sec for example 0 1 sec the instrument operator independently measures the peak sound intensity during the recording using a standalone sound level meter and enters this value in the input interface 31 the calibration unit 32 uses.