NOISE MONITORING APPARATUS

An apparatus for monitoring the noise which impinges a human ear and for generating a signal representing the noise level accumulated over a period of time. Typically, the apparatus can be located in a hearing protector worn by a worker in a noisy environment. A microphone generates a signal having a magnitude representing the detected noise level of the ear which signal is processed by an absolute value circuit and a root mean square circuit to generate a signal having a magnitude proportional to the logarithm of the detected noise level. This logarithmic signal is converted by a voltage to frequency converter and a counter accumulates a count total proportional to the noise level over a period of time. The apparatus includes visual and aural alarms to indicate a maximum allowed noise level and dosage. The apparatus can also be inserted into a storage unit for reading the data, calibrating the noise monitor circuitry and recharging the batteries in the apparatus.