EVALUATION OF CANINE EAR DEFENDERS

Abstract : Concern for hearing impairment of Air Force personnel as a result of turbojet noise led Air Force veterinarians to speculate that similar impairment may occur among Air Force sentry dogs. It was the purpose of this project to develop and test canine ear defenders and to evaluate the feasibility of using them in Air Force dogs. Three basic types of ear defenders were developed: universal earplugs, molded earplugs, and external earmuffs. Eighteen dogs were used to evaluate the ear defenders under conditions ranging from acoustical chamber to flight-line runup of operational aircraft. Exhaust noise levels, as recorded, ranged to 128 dB at all frequencies (20 Hz to 20 kHz) and intake noise levels ranged to 115 dB at all frequencies. None of the dogs showed any apprehension to, or discomfort from, the noise without earplugs, although one dog gave evidence of somatic damage from the 128 dB noise level. It was, therefore, impossible to establish an end point for testing the protective devices. Earplugs were rejected as a means of protection because only 1 of the 18 dogs would tolerate them. Earmuffs were also rejected because the position of the canine ears precluded adequate application of the muffs. Recommendation was made to rotate and selectively station dogs found apprehensive of noise.