Abstract: Passive detector structures for imaging systems are provided, which are based on a coefficient of thermal expansion (CTE) framework. For example, an imaging device includes a substrate, and a photon detector disposed over a surface of the substrate. The photon detector comprises a stack of thin film layers including a resonator member and an unpowered detector member. The resonator member generates an output signal having a frequency or period of oscillation. The unpowered detector member has a CTE, which causes the unpowered detector member to expand or contract due to thermal heating resulting from photon exposure, and apply a mechanical force to the resonator member. The mechanical force causes a change in the frequency or period of oscillation of the output signal generated by the resonator member, wherein the change in the frequency or period of oscillation is utilized to determine an amount of photon exposure of the photon detector.

Abstract: A hearing aid is permanently adjusted to match prescribed amplification characteristics at predetermined frequencies. A single channel filter (24) includes three identical filter stages (60, 62, and 64) that are optionally cascaded in series. Each of the filter stages (60, 62, and 64) exhibits a frequency response curve having a first corner frequency (36) below which the magnitude of the response curve approaches a predetermined minimum value, a second corner frequency (38) above which the magnitude of the response curve approaches a maximum value, and a predetermined gain in magnitude between the minimum and maximum values.

Abstract: A signal processing circuit is incorporated into an audio reproducing device for suppressing noise while preserving distinctive features of speech. A noise detecting circuit includes a low pass filtering circuit (12) and a level detector (14). An output signal (C) from the detecting circuit controls a variable high pass filtering circuit (20) to attenuate a range of low frequencies of an input signal (A) proportional to the detected level of noise. The variable high pass filtering circuit exhibits a family of variable response curves (22, 24, and 26) that vary in slope below a common cut-off frequency (28) that is below a range of frequencies that convey a majority of second formant transitions between consonants and vowels.