Active hearing protectors
First Claim
1. A hearing protective device comprisinga headset having a headband;
- audio transducer assemblies secured to opposite ends of said headband;
each of said audio transducer assemblies including a microphone and a sound reproducer;
circuit means including two respective stereo audio channels connecting said microphone and said sound reproducer of each of said respective audio transducer assemblies;
attenuation circuit means having an input connected to receive simultaneously the outputs of said microphones;
said attenuation circuit means includingmeans to generate two symmetrically similar attenuation current signals with amplitudes in accordance with the combined outputs of said microphones;
said generating means includinghyper automatic gain control circuitry means to substantially progressively lower output currents of said stereo audio channels as the combined outputs of said microphones continue to rise after exceeding a predetermined level;
and means to feed back the respective attenuation current signals to said stereo audio channels at locations therein which affect respective output currents of said stereo audio channels;
said headset having movable switching means mounted thereon to switch said headset on and off.
1 Assignment
0 Petitions
Accused Products
Abstract
A hearing protective device consisting of a headset having opposite earmuff and/or earplug assemblies resiliently connected by a headband assembly including a normally open power switch closed when the headband assembly is put on the user'"'"'s head. The switch controls the energizing of the electrical circuitry of the device. Each earmuff and/or earplug assembly has an outwardly-facing microphone and an inwardly-facing sound reproducer, connected to circuitry defining respective stereo channels, each channel including preamplifier circuitry and a respective power amplifier drivingly connected to one of the sound reproducers. The circuitry also includes a hyper AGC circuit which receives and sums signals from the amplifier chain and derives attenuation signals therefrom which are fed back to the amplifier circuitry and which reduces the gain of this circuitry when the input sound exceeds a certain level. This causes the inputs to the power amplifiers to fall when the input to the preamplifiers increases beyond a certain level. A balanced attenuation circuit arrangement is employed which reduces the size of too-large sound waves without altering their shape, whereby the volumes of the two stereo channels are maintained in the proper relation to each other to preserve binaural hearing.
48 Citations
9 Claims
-
1. A hearing protective device comprising
a headset having a headband; -
audio transducer assemblies secured to opposite ends of said headband; each of said audio transducer assemblies including a microphone and a sound reproducer; circuit means including two respective stereo audio channels connecting said microphone and said sound reproducer of each of said respective audio transducer assemblies; attenuation circuit means having an input connected to receive simultaneously the outputs of said microphones; said attenuation circuit means including means to generate two symmetrically similar attenuation current signals with amplitudes in accordance with the combined outputs of said microphones; said generating means including hyper automatic gain control circuitry means to substantially progressively lower output currents of said stereo audio channels as the combined outputs of said microphones continue to rise after exceeding a predetermined level; and means to feed back the respective attenuation current signals to said stereo audio channels at locations therein which affect respective output currents of said stereo audio channels; said headset having movable switching means mounted thereon to switch said headset on and off. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
Specification