How to check if that ultrasonic mouse repeller works with your phone


I’m sure some people have one or more of those plug-in mouse repellers that claim to keep your home rodent free. Sure they have an LED or even flashy lights to indicate operation, but that does not mean it’s actually emitting any sound. Some fakes sold online (e.g. eBay) actually have nothing other than a few LEDs inside.

While generating test tones with the Audacity (an open source sound editor), I was quite surprised to see just how high tones my phone can pick up. The spectrum analyser App I’m using below is Audizr and the following screenshot shows what happens when I play a 40000Hz test tone in Audacity, well above the human hearing range. For comparison, 16000Hz is the highest tone I can hear:

To get Audizr to sample that high, go into Settings, then Microphone and change the Sampling Range to 96000Hz. Close out of the App and relaunch it. If there’s no 96000Hz option, the phone probably does not sample that high, in which case choose the 48000Hz option.

As most ultrasonic repellent devices operate around 20kHz up, I walked up to our solar powered unit outside our kitchen window. This is motion activated, which keeps our cat from catching birds off the window feeder and is surprisingly effective. Being solar powered, I often wondered if it was still working since our solar garden lights barely work in the winter. Sure enough, there were plenty of tones being emitted above the 20kHz range, not surprising given that our cat clearly avoids that area. :grin::


I checked a few mouse repellers around my workplace. Although we’ve never had a mouse problem, I often wondered whether the repellers are still emitting any sound.

One thing I found is that size matters. The sound from the small plug-in ones dissipates to almost nothing just a few steps away, where as the large ones with switches emit a lot more tones. Surprisingly, none are as loud as the solar powered garden repeller I’ve at home. The following is from the “PestClear 2000” with my phone near the unit. I was standing much further away with the above measurement.

Now for a “repeller” with pretty lights …


… and no action … :thinking:

For anyone that can’t hear a CRT (old tube TV) whistle, the following is while standing in a room with an old chunky CCTV monitor, with a clearly audible tone amongst the whirring fans: