Hi-Res Audio Wireless with LDAC: The WF1000XM4 earphones support Hi-Res Audio Wireless thanks to LDAC. Even compressed music files are upscaled, with our evolved DSEE Extreme technology by delivering a richer, more complete listening experience. Smart feature Speak-to-Chat: It automatically pauses the music on the 1000XM4 and lets in ambient sound so you can conduct a conversation handy if you want to keep your headphones with mic on, or your hands are full. For total convenience, these Bluetooth headphones can be paired with two Bluetooth devices at the same time. So when a call comes in, your headphones know which device is ringing and connects to the right one automatically. Firmware update is required. Firmware will be available in November 2022.