| 摘要 |
There is disclosed a signalling device for making hard of hearing persons aware of an impending happening in his or her proximity. The device comprises a sound transducer such as a microphone for converting sounds to electrical signals, an amplifier for amplifying the electrical signals and a selective filter connected to the amplifier for selecting amplified signals above a selected amplitude level and within a selected frequency range as may be produced by automobile horns, fire, police and emergency sirens, burglar and smoke alarms, door bells, barking dogs, and the like to produce a continuous, periodically pulsating control signal. These control signals are supplied to an indicator means such as a flashing light-emitting diode connected to a person's spectacles or a tactile alarm secured to the wrist of the person to provide a vibrating or pulsating signal to a sensitive area of the body such as the mastoid bone or the wrist or, alternatively, the device may be connected to a male-female electrical connector with a built-in electronic switch activated by the unit so that a lamp or light bulb plugged therein is turned on and off periodically to awaken the hard of hearing when a smoke alarm or whatever signal is detected.
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