ears in only one ear or as many patients indicate when asked where they hear the tinnitus they respond in their head without reference to either their right or left ear referring again to fig1 the structure and operation of applicant 39 s preferred embodiment of apparatus for treating monofrequency tinnitus patients will be further described a phase shift network 30 may be of any type known to those skilled in the auditory and electrical arts applicant 39 s preferred embodiment of sound generator 10 is of the type commercially available from agilent as model 3312a function generator which incorporates an output waveform phase shift feature to select the waveform phase shift feature an operator may dial in the desired phase shift scaled in degrees by turning knob 22 to the appropriate phase shift factor e g 10 degrees 20 degrees etc which affects the desired shifts e g of delta 1 delta 2 etc as shown in fig2 as shown in fig1 a gang switch 32 in its position illustrated connects the output of sound generator 10 to the patient 39 s headphones 12 which preferably is a high quality headset commercially available e g from bose inc of massachusetts usa under the trademark quietcomfort if the sound generator 10 does not have a phase shift feature a separate phase shift network 30 of.