How hearing works in dogs, cats, and people
A dog whistle works because dogs hear sounds we cannot. Here is a clear, practical look at how hearing range works across species, why ultrasound is audible to animals but not to us, and what that means for using a whistle responsibly.
Sound is a vibration in the air, and we describe how fast it vibrates in hertz (Hz): the number of pressure cycles per second. A low rumble might be 50 Hz; a high whistle might be 15,000 Hz, usually written 15 kHz. Hearing range is simply the band of frequencies an ear can detect, from the lowest pitch to the highest.
For a healthy young person, that band runs from roughly 20 Hz to 20 kHz. The low end stays fairly stable through life, but the top end falls steadily with age, a change called presbycusis. Most adults lose access to the highest frequencies first, which is why a 14 kHz tone that a teenager hears clearly may be silent to someone in their forties.
The gap above 20 kHz is what we call ultrasound: vibrations too fast for human ears but well within reach for dogs and cats. A "silent" dog whistle is not truly silent. It simply plays in that ultrasonic band, so the dog hears a clear tone while the people nearby hear almost nothing.
The wide high-frequency hearing of dogs and cats is not an accident. Their wild ancestors hunted small prey such as rodents, and rodents communicate and rustle in the ultrasonic range. An ear tuned to those high pitches helps a predator locate a mouse in long grass or under snow.
There is also a physical pattern at work. Across mammals, animals with smaller heads and ears tend to hear higher frequencies. A smaller head means the two ears are closer together, so to judge where a sound came from the animal benefits from sampling shorter, higher-frequency wavelengths. The result is that compact predators like cats sit at the very top of the mammalian hearing chart.
This is the whole basis of an ultrasonic dog whistle. By producing a tone above what people can hear, you create a signal that is distinct, carries well, and is not buried under everyday human speech and noise. If you want to hear how this plays out in practice, our guide for dogs covers the frequencies dogs respond to most readily.
Inside the inner ear sits the cochlea, a coiled, fluid-filled tube. Running along its length is the basilar membrane, lined with thousands of tiny sensory cells called hair cells. When sound enters the ear, it sets this membrane vibrating, and different parts of it respond to different pitches.
The base of the cochlea, near the eardrum, is stiff and narrow, so it resonates to high frequencies. The far end, the apex, is floppier and wider, so it responds to low frequencies. This orderly layout, called tonotopy, means pitch is effectively mapped onto position: a high whistle excites hair cells at one end, a low hum excites cells at the other.
A dog's cochlea simply has hair cells tuned to higher frequencies than ours, extending the map upward into the ultrasonic range. The trade-off is real but modest. Hearing higher does not mean hearing "better" in every way; it means the dial is set to a different band.
To a dog, an ultrasonic whistle is a clean, attention-grabbing tone that stands apart from the general clutter of household noise and human voices. It is consistent in pitch every time, which is exactly what makes it useful for training. A spoken cue varies with your mood, your accent, and how tired you are; a whistle tone does not.
That consistency is the practical payoff. A dog learns to associate one steady, unmistakable sound with a specific action or reward. Because the tone is unfamiliar and distinct, it tends to cut through distractions at a distance better than a called name. Our training guide walks through how to pair a tone with rewards so it becomes a reliable cue.
It is worth being honest about what a whistle does and does not do. It is an attention and communication tool, not magic. A whistle cannot teach a behaviour on its own, and it will not override a dog that has had no practice with it. The tone gets your dog's attention; the training you build around it does the rest.
Frequency tells you the pitch of a sound; decibels (dB) tell you how loud it is. The decibel scale is logarithmic, so every 10 dB increase represents roughly ten times the sound energy and sounds about twice as loud to us. A quiet room sits near 30 dB, normal conversation around 60 dB, and busy traffic around 80 dB.
For people, prolonged exposure above about 85 dB carries a risk of hearing damage over time, which is why that figure is a common workplace guideline. Dogs are more sensitive to high-frequency sound than we are, so a tone that seems faint to you can be quite prominent to them. The sensible approach is restraint.
Used gently, a whistle is a humane way to communicate. The goal is a clear signal your dog notices, not the loudest sound you can produce.
A web-based whistle can generate any frequency you ask for in software, but the sound still has to leave a physical speaker, and small speakers have real limits. This is the single most important thing to understand when using a digital dog whistle.
The tiny speakers built into phones and laptops are tuned for speech and music, roughly the 200 Hz to 15 kHz range. As you push toward and beyond 18-20 kHz, most of them roll off sharply: the requested tone is generated, but very little of it actually comes out as usable sound pressure. Some devices cannot reproduce true ultrasound at all.
What this means in practice is that a phone or laptop is unlikely to deliver the full 30-45 kHz that a dedicated hardware whistle reaches. The good news is that you usually do not need to. Many dogs respond well to tones in the 15-20 kHz range, which sits at the edge of human hearing and within reach of better speakers. Start in that band, watch your dog, and adjust.
You can experiment with frequency and volume directly using our dog whistle, and the FAQ answers common questions about which settings tend to work on everyday devices.