Do dog whistle apps actually work?

A dog whistle app can get a dog’s attention for a moment, because dogs hear high pitches very well. It cannot produce true ultrasound, because an iPhone’s speaker path runs at 48 kHz and its output falls away above roughly 18 to 20 kHz. And a tone that predicts nothing stops working within days. Used as a cue you have trained, a tone is useful. Used as a magic off-switch, it isn’t.

What can dogs hear that we can’t?

The classic measurements (Heffner, 1983) put a dog’s hearing range at about 67 Hz to 45 kHz, against roughly 20 kHz at best for a young adult human. But range is not sensitivity. Dogs hear best around 8 kHz, where the quietest sound they can detect is near 0 dB SPL, and they stay very sensitive from 4 to 16 kHz. Above 20 kHz their thresholds climb steeply; by 45 kHz a sound has to be around 60 dB just to be noticed.

Approximate hearing thresholds for dogs. Lower means more sensitive. Sources: Heffner 1983; Guérineau et al. 2024.

So ultrasound is not a secret channel to the dog. It is the part of his hearing that works worst. An ordinary high pitch that you can hear too reaches him far better than anything “silent”.

Can a phone make an ultrasonic whistle?

No. iPhone audio hardware runs at a 48 kHz sample rate, which caps any output at 24 kHz in theory, and the speaker itself rolls off well before that. An app that promises “25 kHz” is promising something the hardware cannot do. Bluetooth makes it stricter still: the common SBC and AAC codecs cut the top of the range, so over a wireless speaker the very highest pitches may not come through at all.

What do the studies say about ultrasonic deterrents?

Not much that is encouraging. In a 1990 trial of three commercial ultrasonic units on 15 dogs, no device repelled all dogs at any frequency or level tested. In 2010, guide dogs exposed to ultrasonic deterrents noticed them and carried on working. We could not find a peer-reviewed trial of a bark-activated ultrasonic collar or fence box at all; the “80% effective” figures on sales pages trace back to no publication.

Why does it work on day one and not on day five?

Novelty. A sudden strange sound makes almost any dog stop and look. If nothing follows, he learns it means nothing: owners of handheld ultrasonic gadgets commonly report the effect fading within days. Some dogs go the other way and become more anxious about sudden sounds, which veterinary behaviourists call sensitization. The psychologist Stanley Coren puts it bluntly: the idea that a silent whistle makes a dog stop barking is a myth, and untrained whistling can provoke more barking.

So when is a tone useful?

When you have given it a meaning. A tone that reliably predicts “be quiet and something good happens” is a cue like any other, and some dogs respond to it better than to a voice. That is how DogHush treats it: the owner’s recorded word is the default, the tone is optional and adjustable, and the app points you to a reward-based way to teach the cue first.

This guide is general information about dog behaviour, not veterinary advice. A sudden change in barking, or barking with signs of distress, is a reason to see a vet.