DIRECTIONAL MICROPHONE

Abstract: Device for use with a microphone, for selective muffling of surrounding noise, consisting of a tube with a closed end that houses the microphone, and an open end that faces the surroundings, distinguished by the tube being coated on the inside with sound-absorbent material.

Description: DIRECTIONAL MICROPHONE BACKGROUND A constant problem for automotive telephony is that noise generated by the vehicle disrupts communication. This problem is naturally more pronounced when the microphone is located far away from the driver. Increased traffic safety is achieved by minimising the number of loose components that are involved in the use of a telephone. It would consequently be desirable to place a microphone in or next to the instrument panel, for example. The following device can be used to make such a microphone selective, so that it picks up proportionately more of the spoken voice and proportionately less extraneous noise. This solution is naturally also applicable to other types of telephones, such as loudspeaker telephones in offices. DESCRIPTION OF THE INVENTION The above-mentioned problems are solved by the invention, which provides a device for use with a microphone for selectively muffling surrounding noise according to the following patent claim 1. Advantageous design variations of the invention are specified in the subordinate patent claims that follow. The invention consists of a tube being coated on the inside with a sound- absorbent surface, such as flock (vertical fibres, which are applied by means of static electricity). The open end of the tube is directed towards the driver's mouth. The microphone is placed at the opposite end of the tube, which is closed. The surface coating muffles sound waves that hit the tube opening at an angle, while sound waves that move down the length of the tube are transmitted to the microphone. The microphone can also be attached to the inside of the tube by coating the outside of the microphone with flock. When two flock-coated surfaces come into contact with each other, a high-friction bond with sound-absorbing properties arises. The microphone can otherwise be installed in sound- absorbent foam material or be suspended in a resilient substance that does not transmit sound waves. To further increase the selective output of the device, several parallel tubes can be fitted. Alternatively, one tube can be divided lengthways by internal partitions. The output can be amplified by shaping the bottom of the tube like a parabola. This concentrates the sound towards the microphone. To make the direction of the entire device adjustable, a friction joint could be fitted at the end of the tube, for example. This could be a ball and socket or hinged joint. A simple way to achieve enough friction for changing the direction of the tube easily, while avoiding the risk of it being changed by vibrations, is to coat the surfaces of the joint with flock. This also pre-empts squeaking when the position is changed. DRAWINGS Figure 1 shows a transverse side view of a device in accordance with the invention. Figure 2 shows a cross-sectional perspective of an alternative model of the invention, where a number of tubes are arranged parallel in close proximity to one another. Figure 3 shows an alternative model of the invention, where the tube is divided into a number of sound channels by means of lengthways partitions. Figure 4 shows yet another alternative model of the invention, where the tube is encircled by a concentric outer tube, which is also coated on the inside with sound-absorbent material. The invention is not restricted to the models of the design featured and described, but can be freely varied within the framework of the following patent claims.

Claims: PATENT CLAIMS 1. Device for use with a microphone, for selective muffling of surrounding noise, consisting of a tube with a closed end that houses the microphone, and an open end that faces the surroundings, characterized by the tube being coated on the inside with sound-absorbent material. 2. Device for use with a microphone in accordance with patent claim 1 , characterized by the sound-absorbent material being made of fibre flock material. 3. Device in accordance with patent claims 1 and 2, characterized by the fibres of the fibre flock material being orientated essentially at right angles to the surfaces to which they are attached on the inside of the tube. 4. Device in accordance with one or some of the preceding patent claims, characterized by a number of tubes being fitted parallel to one another. 5. Device in accordance with one or some of the preceding patent claims, characterized by the tube being encircled by one or several concentric tubes. 6. Device in accordance with one or some of the preceding patent claims, characterized by the tube being divided into a number of parallel sound channels by means of lengthways partitions. 7. Device in accordance with one or some of the preceding patent claims, characterized by the closed end of the tube being shaped like a parabola, to which the microphone is attached in the centre. 8. Device in accordance with one or some of the preceding patent claims, characterized by the microphone being attached to the closed end of the 5 tube by means of a flock coating, which acts jointly with the flock coating on the inside of the tube. 9. Device in accordance with one or some of the preceding patent claims, characterized by the microphone being attached to the closed end of the tube by means of foam material, or suspended in a resilient substance. 10. Device in accordance with one or some of the preceding patent claims, characterized by the direction of the device being adjustable by means of anchoring it to the mounting with a friction joint, such as a ball and socket joint or a hinged joint. 11. Device in accordance with patent claim 10, characterized by the surfaces of the friction joint being coated with fibre flock material.

Inventors: ULLMAN JOHAN, ULLMAN, JOHAN
Applicants: ULLMAN JOHAN, ULLMAN, JOHAN
Application year: 1999
Main classification: H04R1
IPC codes: H04M1, H04R1