Experiments in electrostimulation as a therapy for sensori-neural hearing loss

Abstract

Since 1969, experiments have been conducted by various laboratories to evaluate an electrostimulation device offered commercially as a therapy for sensorineural hearing loss. The device manufactured by Intelectron Corporation passes an amplitude modulated high-frequency carrier current through a subject's head by means of an array of four electrodes worn in the manner of a set of headphones. The therapy requires electrostimulation for approximately one hour per day, five days per week for a period of six weeks to produce an improvement in speech discrimination. Groups receiving active electrostimulation have been compared with control groups receiving simulated treatment. Results have been quite variable among the laboratories and have led to considerable controversy as to the effectiveness of the therapy. The success of the therapy achieved by the Pennsylvania State University and the UCLA Medical Center has allowed these experiments to continue and has shed much light on the procedures required to produce the greatest improvements. A recent experiment at Penn State involving tests of evoked responses and middle ear reflex measured before and after therapy produced some unexpected results. The improvements obtained in speech discrimination in this most recent experiment were so marginal that an investigation was launched into the effects of the placebo switch box on the therapy current. These findings to be presented help explain the success or failure of previous experiments and provide information needed to improve the efficiency of the therapy.