Active Noise Reduction: 3-layer hybrid active noise cancellation. 1. An outward-facing microphone captures external noises and fights them with the same counter-sound to eliminate ambient noise first. 2. An inward-facing microphone captures internal sounds in the ear canal and produces a countersound again to neutralize the remaining noise twice. 3. The ear plugs prevent 90% of the noise from entering the ear canal. Transparent Mode The transparent mode allows you to hear what you want to hear, allowing external noises to penetrate and hear and interact with the world around you. You can clearly hear announcements from airlines or subways and everything said around you without removing the headphones. Built-in dual noise reduction microphone. Dual microphone noise reduction system suppresses ambient noise. A dedicated internal microphone and two external microphones capture your voice and isolate it from outside noise. Optical sensor technology: thanks to optical sensor technology, the headphones detect when they are in your ears and stop when you take them off. A high-precision contact sensor has been optimized for daily use and sports activities to detect real-time traffic status. 【Charging on the go】TOZO NC9 wireless earbuds provide more than 10.5 hours of playtime per charge and a total of 24 extra hours in the compact charging case. In active noise reduction mode, they can provide more than 7 hours of playback. They offer convenient charging without cables. [Suppression active du bruit] Suppression active du bruit hybride à 3 couches. 1. Le microphone orienté vers l'extérieur détecte les sons externes et les contre avec un anti-bruit égal pour annuler le bruit. 2. Le microphone orienté vers l'intérieur écoute le conduit auditif à l'intérieur pour capter les sons internes et produire à nouveau un anti-bruit pour doublement annuler le bruit résiduel. 3. Les coussinets empêchent 90 % du bruit de pénétrer dans le conduit auditif.