(The amount of innovation in anti-anti-scraping that's resulted from "sneaker bots" - automated scalping of limited-edition shoe releases - is astounding, and somewhat relevant here in how an environment can become adversarial in ways that impact broad ecosystems. I suppose the equivalent here would be environmental ads that seek to penetrate noise-cancellation in a similar way.)
I suppose, though, that all this is good news for a company that wants to turn your bicycle bell into a subscription product!
On a more serious note: the loud beeping backup alarms were DESIGNED to be annoying and difficult to miss. I would not be surprised in the least if a study showed these "less annoying" backup alarms correlating to a higher number of children being run over by reversing vehicles.
This was developed especially for use in backup heavy environments like harbors where workers started ignoring constant beeps.
Through acoustic testing, the research team identified a narrow frequency band – a “safety gap” – capable of penetrating ANC headphone filters. This range lies between 750 and 780 Hz.
Is there a standard specifying this "safety band"? Is whatever Apple does for AirPods a de-facto standard?
https://cdn.skoda-storyboard.com/2026/04/Skoda-DuoBell-Resea...
As expected ANC headphones cancel less noise at low frequencies so I guess the 780Hz is a trade off between high enough frequency to be a bell and low enough frequency to get attenuated a little bit less than high frequencies.
The research paper is pretty poor quality and this is mainly a marketing exercise.
Yeah, that's what LLMs do. Now is it true? Who knows!