Headphones

If you want a transducer to go out to 20kHz in a well behaved way then it needs to have the headroom beyond 20kHz to do this effectively.

The extended range helps stop roll-off in the sub-bass and high-treble.

That adds kick and brightness to the lowest and highest notes. Since the drivers CAN go beyond human hearing it also means that the limits of human hearing are WELL within the abilities of the drivers--without pushing their physical and electronic limits.

Simply, if you slap a filter on it, you will screw up the sound.

To make price higher, that kind of snake oil you can't see and can't hear 😂

Practical answer- more work to cut it off, doing so might cause artificial impact on the audible range.

I can't be the only one here who shares my headphones equally with my pet chinchilla.

To add another point, just b/c headphones can play to 38kHz does not mean it will be used. I’m not sure of a lot of context that even is mixed to include frequencies so high.

I think sometimes you're just so emotional and moved by a song or an artist that you want to share that moment with your dog... and you dog can hear above 20kHz

So your dog can enjoy them, too.

so you can annoy the fuck out of your dog

Also, when it is said that human hearing goes up to 20kHz, this is true for young healthy people. when you are 20, you are typically not hearing anything above to 18kHz already.

Pro here: it's because it means it will operate comfortably within the human hearing range. Think of it the same way you would think about headroom. Also, just because you don't hear it, doesn't mean you don't feel it.

im pretty sure i can hear a good amount past 20khz if its the only sound, but otherwise its indiscernible and im pretty young too

Drivers are dumb objects, and will reproduce anything you give it, they can't differentiate between frequencies. You can design a driver to reproduce significantly above 20kHz on purpose, but that isn't done very often. Being able to produce >20kHz is just how the driver and pad and enclosure design will often turn out. Just about any modern headphone will be capable of producing at least slightly >20kHz at lower volume than the rest of the range.

You don't stop ultrasonic frequencies from being reproduced with the headphones, you stop them in the mastering step of creating music by cutting them off, by rendering the song at 44.1kHz sampling rate, or by setting the audio output to your DAC to 44.1kHz.