Need polishing: Is the online-sold "ultrasonic dog repeller" really effective? What is the working principle of dog repelling?

Is the "ultrasonic dog repellent" sold online really effective? What is its working principle?

Recently, a friend asked me curiously, "Can the 'ultrasonic dog repellent' really repel dogs? What is its working principle?"

After searching online, I found that the "ultrasonic dog repellent" my friend asked about was invented by Wu Zhongjie, an authority in the field of ultrasonic technology, and it is called "Anti-Dog Sword". There was a special report on it in the CCTV program "I Love Invention".

After a detailed search for information, I have a thorough understanding of the working principle and effect of the ultrasonic dog repellent.

Now, let me explain its working principle to you.

First, it's important to know that the human hearing range is 20-20,000 Hz, while a dog's hearing range is 15-50,000 Hz.

The ultrasonic dog repellent uses a frequency of 25,000 Hz, which is inaudible to humans but can be heard by dogs. It emits a sudden, intense "explosive" sound that stimulates a dog's auditory and nervous systems, making the dog feel scared and thus repelling it. The 25,000 Hz sound is inaudible to humans and does not cause any disturbance or irritation; however, it can effectively stimulate dogs without causing any