Abstract: Various embodiments of an earbud and an ear-wearable electronic device that includes such earbud are disclosed. The earbud includes an elongated body having a first end, a second end, a cavity extending along a body axis between the first end and the second end of the elongated body, and a body acoustic port disposed in the first end of the body and acoustically coupled to the cavity of the body. A portion of the cavity adjacent the body acoustic port includes a cross-sectional area in a plane orthogonal to the body axis that increases in a direction from the second end of the body to the first end of the body. The earbud further includes a flange connected to the elongated body and a wax bridge disposed on an outer surface of the flange along the body axis and over the body acoustic port.

Abstract: A substrate is etched in a vacuum enclosure in a process which generates plasma light emission. The process is monitored by passing emitted light via a window, a thin film narrow band filter and a “Fabry-Perot” etalon to a detector. The output signal from the detector is analyzed by shape recognition techniques to derive a measure of the progress of the process. The shape recognition preferably makes use of digital filtering and comparison with reference data derived from the theoretical analysis or from a calibration run.