Abstract: A security system includes a transducer within a monitored space responsive to audio signals therein. An analog-to-digital converter couples the transducer to the input of a digital signal processor. Time-staggered digital samples are stored, and are each multiplied by the current sample in a corresponding series of multipliers, and accumulated in a like series of accumulators. Accumulated sums, generated by the series of accumulators during known, undisturbed periods, are stored. During active monitoring, the processor compares currently generated accumulated sums to the previously stored accumulated sums generated during undisturbed periods. The processor creates an alarm signal when current values for the accumulated sums do not correspond to accumulated sums previously stored during undisturbed periods.

Abstract: A system for heating water includes a first tank containing water and a heater element for heating the water, a solar panel, a control circuit coupling the solar panel to the heater element, and a second tank. The control circuit couples power to the heater element in proportion to available sunlight. The maximum temperature of the water in the first tank is higher than the maximum temperature of the water in the second tank. Water is drawn from the system through the second tank.

Abstract: A hearing aid includes at least one capacitive switch for controlling or communicating with the hearing aid by touch. The capacitive switch is an electrode on the inside of the housing coupled to a touch detector. Touching the outside of the hearing aid adjacent the electrode produces a switching operation. The hearing aid includes a programmed microprocessor coupled to the touch detector. The microprocessor is programmed to effect predetermined functions in response to particular touch patterns.

Abstract: A hearing aid having a plurality of frequency bands is calibrated by evaluating the response of the hearing aid in each band and programming the hearing aid to produce a specific sound pressure level in each band, thereby providing a calibrated instrument that can be used for both evaluation and compensation of hearing loss. The sound pressure levels are preferably the same for each band. The evaluation step is preferably performed at the center frequency of each band.

Abstract: A hearing aid includes a case and a photovoltaic cell located in the case near a translucent portion of the case. A detector circuit includes a voltage comparator for monitoring the voltage from the photocell and indicating variations in voltage. The variations are analyzed to detect data for operating the hearing aid.

Abstract: Data is transferred to and from a hearing aid by transmitting an audible carrier having a frequency greater than 5 kilohertz, modulating the carrier with data, and detecting the modulated carrier in the hearing aid with a narrow band filter. The frequency is in a region where impairment occurs and there are many other sounds, thereby masking the communication, yet not interfering with it.

Abstract: A remote control unit includes an RF transceiver that complies with a Bluetooth® standard and an RF transmitter that does not comply with the Bluetooth® standard, whereby the remote control unit serves as a wireless gateway between Bluetooth® compliant devices and the hearing aid. The hearing aid can further include a transmitter and the remote control unit can further include a receiver, neither of which comply with the Bluetooth® standard. The transmitters operate in the ISM band at low power, minimizing power dissipation within a hearing aid.

Abstract: A hearing aid is identified by storing a binary code in the hearing aid, receiving a transmitted code, reading out a subset of bits from the stored binary code, and comparing the transmitted code with the subset for identification. The reading step preferably reads the lowest order nibble, byte, or word of the binary code. In accordance with another aspect of the invention, a charger for the hearing aid, a controller for the hearing aid, and a programmer for the hearing aid store the identification codes for two way communication among the devices.

Abstract: A hearing aid is identified by storing a first binary code in the hearing aid as a first identification code, storing a second binary code in the hearing aid as a default code, and replacing the default code with a second identification code if a second hearing aid is used by the person using the first hearing aid. The identification code includes a bit indicating for which ear the hearing aid is intended. If two hearing aids are used, the identification code of the first hearing aid is substituted for the default code in the second hearing aid and vice-versa, thereby pairing the first hearing aid with the second hearing aid and indicating that there are two hearing aids needed, even if one hearing aid should become lost or inoperative.

Abstract: A remote control unit includes an RF transceiver that complies with a Bluetooth® standard and an RF transmitter that does not comply with the Bluetooth® standard, whereby the remote control unit serves as a wireless gateway between Bluetooth® compliant devices and the hearing aid. The hearing aid can further include a transmitter and the remote control unit can further include a receiver, neither of which comply with the Bluetooth® standard. The transmitters operate in the ISM band at low power, minimizing power dissipation within a hearing aid.

Abstract: A hearing aid includes at least one capacitive switch for controlling or communicating with the hearing aid by touch. The capacitive switch is an electrode on the inside of the housing coupled to a touch detector. Touching the outside of the hearing aid adjacent the electrode produces a switching operation. The hearing aid includes a programmed microprocessor coupled to the touch detector. The microprocessor is programmed to effect predetermined functions in response to particular touch patterns.

Abstract: A maintenance station includes means for disinfecting, drying, recharging, and communicating with one or more hearing aids using light. In a preferred embodiment of the invention, a fluorescent lamp is primarily for disinfecting a hearing aid, an incandescent lamp is primarily for recharging a hearing aid, and a light emitting diode is primarily for communicating with a hearing aid. All power dissipated within the station aids in drying the hearing aids within.

Abstract: A hearing aid includes a case and a photovoltaic cell located in the case near a translucent portion of the case. A detector circuit includes a voltage comparator for monitoring the voltage from the photocell and indicating variations in voltage. The variations are analyzed to detect data for operating the hearing aid.

Abstract: A hearing aid includes a case, a photovoltaic cell located within the case, and a light gathering member optically coupled to the photovoltaic cell. The photovoltaic cell is preferably a multi-junction cell and the light gathering member gathers light at the wavelengths preferentially absorbed by the multi-junction cell.

Abstract: A hearing aid having a rechargeable battery and a charger for charging the battery includes a first microphone and a first speaker in the hearing aid and a second microphone and a second speaker in the charger for acoustically transferring data between the hearing aid and the charger. The hearing aid can detect the charge state of a battery and send a signal to the charger indicative of the charge state. The charger also includes a chamber for receiving at least a portion of the hearing aid.

Abstract: A hearing aid includes a secondary battery and means for identifying the kind of battery for charging. After the battery is identified, an appropriate algorithm for charging the battery is selected and used for charging the battery. Primary batteries are not charged. The hearing aid also includes a voltage reduction circuit for supplying a constant voltage to circuitry within the hearing aid. The battery preferably has an energy density greater than 500 watt-hours per liter.

Abstract: A system for positioning a solar panel includes a first frame and a second frame substantially parallel with the first frame. A plurality of tubes intersect the first frame and extend through the second frame. Each tube has a free end and a distal end. A photovoltaic device attached to the free end of each tube and the distal end is coupled to the first frame. Relative motion of the frames tilts the tubes and the photovoltaic devices, thereby permitting the photovoltaic devices to track the sun during the day.

Abstract: A system for heating water includes a first tank containing water and a heater element for heating the water, a solar panel, a control circuit coupling the solar panel to the heater element, and a second tank. The control circuit couples power to the heater element in proportion to available sunlight. The maximum temperature of the water in the first tank is higher than the maximum temperature of the water in the second tank. Water is drawn from the system through the second tank.

Abstract: A hearing aid includes an antenna and is powered by one or more signals received by the antenna. At least some of the power for operating the hearing aid is derived from a received signal. Power not used for operation is used for charging a battery, if any, in the hearing aid. The signal can be modulated for one-way communication or there is two-way communication if the hearing aid includes a transmitter coupled to the same antenna or a second antenna.

Abstract: A system for heating water includes a first tank, a solar panel, a control circuit, and a second tank for receiving water from the first tank. There is a first resistive heating element in the first tank and a second resistive heating element in the second tank. The control circuit couples power from the solar panel to the second resistive heating element unless the water in the second tank is at a preset maximum temperature, then the control circuit couples power to the first resistive heating element. If the water in the second tank is below a preset maximum temperature and above a preset minimum temperature, then the control circuit couples power from the solar panel to both the first heater element and the second heater element. If the temperature of the water in the second tank is below a preset minimum temperature, then the control circuit turns on conventional heating means in the second tank. Water is withdrawn from the second tank for use.