Dogs can hear higher pitches than people, which is why silent whistles work for them.

The longer version

Canine ears respond well above the human ceiling, into a band where our sensitivity has already fallen away. Whistles built for that band emit almost nothing audible to us yet plenty that a dog detects easily, so the caller seems to be making no noise at all.

Selective breeding and a mobile outer ear both help: the flap can swivel to gather a weak signal and judge direction. Many small mammals sit even higher, which is why pest deterrents aim their output where rodents hear best. The trade-off is that very high vibrations fade quickly in air, so such calls work best over short distances.

Where this entry sits

Sound and Music gathers facts about how vibrations move through air and water, how ears turn them into meaning, and how instruments and notation shape what listeners hear. Expect echoes, pitch, volume, acoustics, and the odd silence in between. The full list sits on the Sound and Music page, where every entry is listed in order.