What is the technical name for the headset feature that prevents anyone on the user side from listening to what they are listening to?

spacemissing

There is no such feature. It is a technical impossibility. (Not just difficult, but truly impossible.)

Robert J

I think you mean, people _near_ the headphone user cannot hear the sounds on the headphones? That is down to the general construction and style of the headphones. You want over-ear, closed-back construction. That means the headphone cushions go around your ears and "seal" to your head - unlike on-ear ones which have small cushions. Closed back means the body construction is an airtight "bowl" so little or no sound leaks out. The opposite are open back, with a mesh or grid etc., some kind of vents that let sound through. Examples - Over-ear, closed back: https://d1aeri3ty3izns.cloudfront.net/media/20/206165/1200/preview.jpg Over-ear, open back: https://d1aeri3ty3izns.cloudfront.net/media/39/398725/1200/preview.jpg On-ear: https://www.amazon.co.uk/Monoprice-Lightweight-Acoustic-Headphones-113191/dp/B014399CWK/ref=cm_cr_pr_product_top?tag=sggp-21&ie=UTF8 "Studio" grade headphones are generally best for minimising sound leakage - they are used for such as a singer listening to a background track while recording vocals, so sound leakage would be a problem.. The Sony MDR-7506 headphones are one of the best in that class, closed over-ear and very cheap for the quality, around $100 or less:

Mamianka

Mute switch. Added - since you went back and better explained what you seek, this makes my response irrelevant - or sounding snarky. Not my intent. Not gonna lose points by removing it, though.

AVDADDY

What you imagine does not exist.