Welcome to our weekly 'Ask a Vet from the SF SPCA' feature on 7x7.com. Dr.Jeannine Berger, DVM, DACVB is a board certified veterinary behaviorist who counsels guardians whose pets’ issues are beyond the scope of training. Think of her as a pet shrink…at your service. Ask your own questions in the comments!

Q: When a police or ambulance siren goes by, my dog wails a high-pitched, mournful howl which continues for several minutes after the siren has passed. What's that about? Is the siren hurting her ears? Is she relaying a danger warning?

A: When dogs hear a siren, you see them tilt their head and prick their ears long before you see the ambulance or police car. As you know, dogs’ hearing is far more advanced than ours, partially because of the shape of their ears, and partially because of the range of frequencies that they can hear. (As an interesting side note, teens can hear higher frequencies than adults and as such, an electronic device that emits a high frequency has been developed and marketed to businesses interested in preventing loitering.)

Sirens need to be loud to be heard from far away and to cut through background noises. Modern sirens employ high-pitched frequencies designed to be perfect to alarm our ears. Most alarms and sirens fall into the frequency range 1-3 kHz, where the human hearing is the most sensitive. The frequency of a soundwave determines its tone and pitch. Frequency is the number of cycles, or complete vibrations, experienced and is measured in hertz (Hz), the standard unit of frequency. The frequency range of human hearing is about 20 to 20,000 Hz, whereas the frequency range of a dog is about 40 Hz to 60,000 Hz (depending on the breed of dog as well as its age).

We don’t really know why dogs howl in response to a siren, but I believe the high-pitched sound of sirens is an auditory perception trigger that elicits a vocal response in some dogs as a form of communication based either on primal response to high-pitched sounds or discomfort. Other loud sounds don’t cause this reaction, so the frequency must trigger a similar alarm in dogs’ ears as they do in ours.