Bats and dogs can hear sounds well beyond what humans can. Police use a special whistle that dogs respond to but is silent to humans. Which property of sound is at work?
AThe whistle is too loud for humans (decibels)
BThe whistle vibrates without a medium
CThe whistle has a frequency above 20,000 Hz — ultrasonic for humans, audible to dogs
DThe whistle is too small for humans to hear
Answer & Solution
Correct answer: C. The whistle has a frequency above 20,000 Hz — ultrasonic for humans, audible to dogs
The dog whistle produces sound of frequency in the ultrasonic range (above ~20 kHz). Dogs can detect this; humans cannot. Loudness is irrelevant — even a loud ultrasound sounds silent to us.
Related questions
Two identical sirens sound, one on a parked car and one on a car speeding towards you. WhaA singer's note makes a piano string sound without touching it. What is happening?Why does the speed of sound in a gas change with temperature?Sound reaches you faster through a steel rail than through the air. Why?A sound is described as periodic. What does that say about the particles of the medium?A vibrating guitar string makes a sound. What does it do to the surrounding air?Why can sound not travel across a vacuum?You drive an oscillating object far above its natural frequency. What happens to the ampli