IL101579A - Active hearing protector - Google Patents

Description

"ACTIVE HEARING PROTECTOR" THE APPLICANT ; - AHARON ADY 46 HATISHBY ST. 46 aim HAIFA na¾n ACTIVE HEARING PROTECTOR.

BACKGROUND OF THE INVENTION.

The invention relates to a headset including earmuffs provided with means for protecting the ear from sounds of high intensity, while at low noise level transmission of voices, music and so ¾n is normal without an disturbance or attenuation.

There exist both active and passive hearing protectors, which either transmit the entire sound scale through microphone and speaker means or by means of a diaphragm which at normal level transmits muted tone quality and dissipates sounds of high intensity before it can reach the inner ear. n both appliances the sound is somewhat distorted, and it is the object of the present invention to provide a hearing protector which will allow sound of normal, non-excessi e intensity to reach the ear-drum without interposition o£ any sound attenuating member and to dampen the sound as soon as it exceeds a given sound pressure level.

It is another object to provide a hearing protector in the form of a headset with earmuffs to be worn by people which have to work in surroundings where excessive noise is not the rule but happens casually and where, under normal conditions, they can listen to talk and receive orders at normal speech level without distortion or attenuation.

And it is a final object to provide a hearing protector of low weight and at low cost, to enable any person working in noisy surroundings to buy and to wear it.

SUMMARY OF THE INVENTION.

The hearing protector according to the present invention includes two ear muffs each including a normally open duct from the outside to "the ear which is partly or totally closed by valve means upon an increase of the noise level above a given number of decibels. Each ear muff comprises a microphone, an amplifier and a potentiometer which are adapted to define the noise level and to energize a magnet or electric motor to close the valve means in accordance with the noise intensity. The valve means may be a flap, a butterfly val e or a rotatable disc with apertures cooperating with apertures on a fixed disc.

In a preferred embodiment of the hearing protector each ear muff includes a normally open duct and a sliding valve connected to a solenoid for closing the duct upon rise of the surrounding noise level above a given intensity. Operation of the solenoid is by an electronic circuit which essentially includes a microphone, means for amplifying and rectifying the microphone output and adjustable threshold comparator means serving to energize the solenoid, as well as a battery supplying the necessary power. The desired maximum sound level can be chosen by the user by adjusting the amplifier gain.

Another embodiment includes a flap mounted inside the duct on a rotatable axle. It can be rotated to close the duct by either an electric motor directly connected to the axle or by a solenoid connected to the axle by lever means A third embodiment of a valve is in the form of a disc rotatably and coaxially mounted close to a similar stationary disc, both discs being provided with cooperating perforations. By turning the rotatable disc about a small angle the perforations of one disc cooperate with the non-perforated portions and thus close the duct. As in the case of the flap-shaped valve rotation of the disc can be effected either h\* an electric motor or by a solenoid by means of a lever transmission.

SHORT DESCRIPTION OF THE DRAWINGS.

Figure 1 is a section thr ugh one earmuff of a headset provided with a first embodiment of the ear protecting device, Figure 2 is a section along line 2-2 of Figure 1, Figure 3 is a section through an earmuff provided with a second embodiment of the ear protecting device, Figure 4 is a section alotjg line 4-4 of Figure 3, and Figure 5 is a diagram of the electronic unit operating the protecting device.

DETAILED DESCRRIPTION OF THE DRAWINGS.

With reference to Figures 1 and 2 an ear muff I is connected to the opposite earmuff of a headset by a stirrup II, shown in part only. It comprises a rigid housing of oval shape consisting of an outside cover 1, an inside cover 2 and an envelope 3; the inside is provided with a border 4 of a soft aud resilient material, such as felt, which surrounds the skull area around the ear and serves as seal again3t penetration of noise, as well as of dust. A cylindrical duct 5 penetrates the outer and the inner housing cover substantially opposite the outer ear canal and is closed by a flap valve 6 rotatably mounted on a shaft 7. An electric motor comprising an anchor 8 and surrounding windings 9 is adapted to rotate the shaft and the flap valve about a right angle from its open position parallel to the duct axis to a closed position perpendicular to the duct axis. The motor is energized by a cell 10 via an electronic unit 11 the components of which are illustrated in Figure 5. A microphone 12 is mounted in the outer housing cover and connected to the electronic unit and the motor by wiring.

Figures 3 and 4 illustrate a hearing protector similar to that shown in Figures 1 and 2, except for the valve and its operation. Those components which are identical in both embodiments have been denoted by identical numerals, and include the housing parts 1, 2, 3, and 4, the battery 10, the electronic circuitry 11 and the microphone 12. The duct 25 is of rectangular cross section and penetrates the outer and the inner cover of the housing opposite the outer ear canal and is closed by a rectangular gate valve 26. The valve moves in and out of the duct in a groove 27 and through a slit 28 in the upper wall of the rectangular t' duct. It is moved by means of a solenoid 29 and a magnetic core 30, the latter being urged out of the duct by means of a helical spring 31.

In both embodiments the microphone emits an output more or less proportional to the noise level; this reaches a driver by way of an electronic circuit, which serves to energize the solenoid or motor causing operation of the valve as soon as excessive noise is received by the microphone. As soon as the noise abates the driver opens the circuit and the valve opens again to its full extent permitting the wearer to hear ordinary talk and normal noise.

A diagram of the electronic unit is shown in Figure 5:- herein the microphone 12 is am amplitude-dependent type such as a crystal type depending on a piezo-electric effect. Its electric output is amplified by a preamplifier and transmitted to a rectifier by means of a filter which has the task of obtaining a total response according to the frequency weighting standard. An adjustable gain allows the wearer to adjust the amplifier to the desired sound level. The rectifier is preferably a half-wave rectifier and transmits the signals to an integrator which emits an output signal - at a voltage proportional to the received sound intensity - to a threshold comparator which emits a high logic level output to a driver, whenever the sound level is above the desired threshold, whereupon the driver energizes the electric motor or the solenoid respectively by closing the circuit to the battery 10. As soon as the sound level dc; ceases below the dangerous intensity, the comparator ceases to emit signals to the driver and the circuit to the solenoid or motor is interrupted.

It is understood that the shown circuit represents only one example of the invention and that other embodiments may be conceived by a person skilled in the art, as long as the desired effect of opening or closing of the valve-is obtained.

It is also understood that other kinds of valves instead of those shown and described in the foregoing may be incorporated in the hearing protector operated by either an electric motor or by a solenoid. It is also evident that both kinds of valves, i.e. a flap valve and a gate valve, cab be employed in closing aduct of either circular, square or rectangular cross section.

The housing is shown to be of oval shape, but any other shape may be designed, such as rectangular, circular or elliptical .

Claims (6)

C L A I M S -.-

1. An active hearing protector positioned in each of the two earmuffs of a headset, each earmuff comprising, a housing adapted to be placed over an ear, and having an outside and an inside enclosing the outer ear, a duct penetrating said housing from outside to inside substantially opposite the outer ear canal, a valve serving to close said duct to prevent excessive noise from reaching the ear, an electric mechanism serving to close and to open said val ve , a microphone on the outside of said housing, an electric power supply, an electronic circuit serving to receive signals from said microphone, to convert said signals to a voltage proportional to the received sound intensity, and to energize said electric mechanism to effect closure of said valve above a predetermined noise intensity, and to open said valve below said sound intensity.

2. The hearing protertor of Claim 1, wherein said valve is a flap valve rotated by an electric motor from an open state of said duct defined by its plane positioned parallel to said duct axis, to a closed state defined by its plane positioned perpendicular to the duct axis.

3. The hearing protector of Claim 1, wherein said valve is a gate valve operated by a solenoid serving to be slid in and out of said duct in accordance with sound i tensit .

4. The hearing protector of Claim 2 or 3 , wherein said duct is of circular cross section.

5. The hearing protector of Claim 2 or 3, wherein said duct is of rectangular cross section.

6. The hearing protector of Claim 1, wherein said power supply is an electric battery, mounted inside said housing.