Aversive responses of dogs to ultrasonic, sonic and flashing light units

Two experiments were conducted to test the ability of various ultrasonic devices to repel dogs at a distance of 1 m. In Experiment 1, three ultrasonic devices (Unit 1, a commercial unit with bursts from 14 to 42 kHz and overall sound pressure of 60 dB; Unit 2 had bursts of 7–15, 25–30, 26–35 and 30–40 kHz, and sound pressure of 75 dB; Unit 3 covered a wide band of 17–45 kHz with sound pressure of 65 dB), an instrument which gave off a flash of light at 2 per second and a pocket alarm (compressed air) were tested on 15 dogs. The dogs were divided into three groups, small (22–32 cm at the withers), medium (46–57 cm) and large (66–87 cm), and within these groups there were long- and short-haired types and breed types. No device repelled all dogs at any specific frequency or sound pressure level tested, although aversive behaviour was noted in several dogs to Units 1 and 3, and the commercial alarm. Experiment 2 was conducted several months after the first one, when the equipment was modified. Fourteen dogs in three similar groupings were used. The instruments tested were two ultrasonic devices driving Hi-Fi commercial tweeters (Unit 1 produced sweeps of 17 kHz-5 kHz-55 kHz with an output of 120 dB; Unit 2 had similar sweep frequencies to Unit 1, but was of unknown dB; Unit 3 had a variance sweep of 20–35 kHz and averaged 118 dB; Unit 4 produced the same variance sweep as Unit 3, but was of unknown dB). Unit 1 had an immediate effect on 13 dogs; 9 reacted aversively, 2 with apprehension and 2 pricked their ears.