Knowles announced its new product to compete in what is commonly known as the “bone conduction” sensor market for TWS (this should not be confused with bone conduction headphones, which transmit audio).
This sensor is used to pick up the vibration of the human skull and to assist with voice pick up in noisy or windy conditions. The main advantage of this is that the captured signal does not contain ambient sound, since the bone conduction sensor captures the vibration of the human skull, only the speech will be present in the captured audio signal.
Typically, a bone conduction sensor is used along with standard microphones so that the high frequency signal can be captured correctly while the bone conduction sensor captures the low frequency signal picked up by the skull.
Apple has used this technique for all its Airpods, with the sensor supplied by STMicroelectronics (this is an accelerometer). Bone conduction is now commonly used across many high end TWS devices. STMicroelectronics is the leading vendor today, but other vendors include BoCo, Goertek, Sonion, Vesper and Knowles.
For a detailed analysis of the market for bone conduction and other components/software in TWS please see the following studies: