GB1599367A - Audiometer - Google Patents

Abstract

The aim in this audiometer is to achieve a largely noise-free transmission of the measurement sound and remote-controlled operation. Audiometer, in which the signal distribution (13 to 15) is performed among the transducers (24, 25) via in each case one level controller (20, 21), so that the number of the measurement points (28 to 32) connected to a signal source (10, 11, 12) is virtually unlimited, because the signal to be transmitted can have levels (20 dB Re 1V) which are high up to the measurement points. This audiometer can be used as intended for testing hearing, in particular in systems having a plurality of measurement points for examining groups of people to be tested. <IMAGE>

Description

(54) AN AUDIOMETER (71) We, SIEMENS AKTIEN GESELLSCHAFT, a German company of Berlin and Munich, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to an audiometer.

Audiometers are described, for example, in German Patent Specification No. 1016 894.

In known audiometers, standard level controls were provided for the various sound transducers, e.g. airborne-sound receivers, bone conduction sound receivers, and loudspeakers, only a single level control being provided for each ear to be tested. Thus, an audiometer with one channel for the left ear and one for the right ear, i.e. with two channels, has only two level controls. Since sound levels of minus 120 dB (re: 1V) are encountered in every measuring device for hearing thresholds, small voltages are connected after the attenuator (level control, decibel divider) and distributed to the aforesaid individua! sound transducers which are also known as transmitters. This distribution of very small voltages is difficult and hitherto has only been achieved satisfactorily with mechanical switches. Because of this, however, the switches can only with difficulty be remotely-controlled and, moreover, mechanical contacts in these distributors are very susceptible to trouble. The effect of these disadvantages is felt particularly in constructions where several measuring points are connected to one signal source. This is particularly the case e.g. with audiometers for testing the hearing of groups.

According to the invention there is provided an audiometer comprising tone generating means, a plurality of acoustic transducers, and a plurality of signal control stages, each signal control stage including a respective semiconductor switch and being connected between an output of the tone generating means and a respective one of the transducers for controlling the level of signals supplied thereto, each signal control stage being near its respective transducer, wherein all of the transducers can be simultaneously supplied with signals from the tone generating means.

By arranging the signal distribution between the tone generating means and the transducers and their respective control stages, an unlimited number of measuring points can potentially be used because the signal to be transferred can have a high level of e.g. 20 dB (re: 1V).

For this reason also, only small demands can be placed on the screening of the signal lines without there being a fear of an increase in the occurring interference pick-up, for example the hum pick-up on the lines is not significant because the signal-to-noise ratio is always high.

Semi-conductor switches are used so that all measuring points connected to a signal line can be provided with their own level controls which can be digitally controllable. The semiconductor switches could comprise standard commercial integrated circuits which are known as digital-to-analogue converters, (e.g.

switches of the group AD 7510 and AD 7530, which are described in specification sheets Dl CMOS "Protected Analog Switches" and "CMOS 10 + 12 Bit Monolithic Multiplying D/A Converters" of the firm Analog Devices, Route 1 Industrial Park, P.O. Box 280, Nordwood, Mass. 02062, U.S.A., and also specification sheet Day76 "Comdac Companding D/A Converter, Monolithic Logarithmic DAC" of the firm Precision Monolithics Inc., 1500 Space Park Drive, Santa Clara, California 95050, U.S.A.) The invention will now be described, by way of example, with reference to the accompanying drawing in which: Figure 1 shows a simple measuring system, and Figure 2 shows a measuring system with several measuring points.

Referring to Figure 1, a tone generator 1 feeds two acoustic transducers 6 and 7 via a line 2 and control stages 3 and 4. The broken line 5 is intended to represent an interface and indicates that the two transducers 6 and 7 can be extended to any desired number. Control of the signal level fed to the transducers 6 and 7 is effected by means of digital signal lines 8 and 9 respectively which can transmit up to 16 bits simultaneously.

In order to test the hearing of a test person, an audio signal is produced by the tone generator 1 and supplied via the line 2 and the control stages 3 and 4 to the transducers 6 and 7 respectively, each control stage 3 and 4, being arranged near to its respective transducer, 6 and 7. In order to effect a measuring examination in this manner, sound signals which strike the test person are varied by means of the digital signal lines 8 and 9, binary words carried by the lines 8 and 9 representing a code for semi-conductor switches contained in the control stages 3 and 4.

Referring to Figure 2, three tone generators 10, 11 and 12 are provided to which lines 13, 14 and 15 respectively are connected. These lines 13, 14 and 15 are connected with re motely-controlled connection switches 16 and 17 which are each provided with corresponding switch (acceptance) contacts. A remotelycontrolled selection of any of the tone generators 10 to 12 is possible by means of the switches 16 and 17, which switches are also known as multiplexers, and by switching lines indicated by arrows 18 and 19. The loudness level of the selected tone signal can then be controlled by way of a level control device 20 or 21 in the manner described with reference to the control stages 3 and 4 of Figure 1.

Here too, remote control is possible, as is indicated by arrows 22 and 23 respectively.

Acoustic transducers 24 and 25 are connected with the level control devices 20 and 21 respectively.

Operation of the multiplexers used as switches 16 and 17 is effected in that, as indicated by the arrows 18 and 19 respectively, a switching signal is supplied by a control device (not shown) such that, by means of switching arms 26 and 27 respectively, one of the tone generators 10 to 12 is selected.

Adjustment of the tone signal level is effected as in the arrangement shown in Figure 1 in that, in the same way, switching pulses are supplied to the level control devices 20 and 21 via a remote control, as indicated by arrows 22 and 23, such that a corresponding adjustment of the tone signal level is effected.

In addition to the two measuring points terminated by the sound transducers 24 and 25, further measuring points 28 to 32 of the same kind are indicated by broken lines as measuring points which can be connected to the tone generators 10 to 12 via the lines 13 to 15 respectively, and which correspond to the two preceding measuring points which are shown in detail. These measuring points 28 to 32 also correspond in their method of operation.

The arrangement need not terminate with the measuring point 32; further measuring points can also be connected.

WHAT WE CLAIM IS: 1. An audiometer comprising tone generating means, a plurality of acoustic transducers, and a plurality of signal control stages, each signal control stage including a respective semiconductor switch and being connected between an output of the tone generating means and a respective one of the transducers for controlling the level of signals supplied thereto, each signal control stage being near its respective transducer, wherein all of the transducers can be simultaneously supplied with signals from the tone generating means.

2. An audiometer according to claim 1, wherein each signal control stage further includes a switching arrangement connected between the tone generating means and the respective one of the semi-conductor switches, for switching sigrials supplied from the tone generating means.

3. An audiometer according to claim 2, wherein the tone generating means comprises a plurality of tone generators, each switching arrangement being arranged to supply its respective transducer with signals from a selected tone generator.

4. An audiometer according to any preceding claim, wherein each semi-conductor switch comprises an integrated circuit known as a digital-to-analogue converter.

5. An audiometer according to any preceding claim, wherein the signal control stages are adapted to be remotely-controlled by means of an arithmetic unit, such as a microprocessor, desk computer (programmable logic away) or process computer.

6. An audiometer according to any preceding claim, wherein each signal control stage is fitted into a housing of its respective transducer.

7. An audiometer substantially in accordance with any example herein described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. lines 8 and 9 respectively which can transmit up to 16 bits simultaneously. In order to test the hearing of a test person, an audio signal is produced by the tone generator 1 and supplied via the line 2 and the control stages 3 and 4 to the transducers 6 and 7 respectively, each control stage 3 and 4, being arranged near to its respective transducer, 6 and 7. In order to effect a measuring examination in this manner, sound signals which strike the test person are varied by means of the digital signal lines 8 and 9, binary words carried by the lines 8 and 9 representing a code for semi-conductor switches contained in the control stages 3 and 4. Referring to Figure 2, three tone generators 10, 11 and 12 are provided to which lines 13, 14 and 15 respectively are connected. These lines 13, 14 and 15 are connected with re motely-controlled connection switches 16 and 17 which are each provided with corresponding switch (acceptance) contacts. A remotelycontrolled selection of any of the tone generators 10 to 12 is possible by means of the switches 16 and 17, which switches are also known as multiplexers, and by switching lines indicated by arrows 18 and 19. The loudness level of the selected tone signal can then be controlled by way of a level control device 20 or 21 in the manner described with reference to the control stages 3 and 4 of Figure 1. Here too, remote control is possible, as is indicated by arrows 22 and 23 respectively. Acoustic transducers 24 and 25 are connected with the level control devices 20 and 21 respectively. Operation of the multiplexers used as switches 16 and 17 is effected in that, as indicated by the arrows 18 and 19 respectively, a switching signal is supplied by a control device (not shown) such that, by means of switching arms 26 and 27 respectively, one of the tone generators 10 to 12 is selected. Adjustment of the tone signal level is effected as in the arrangement shown in Figure 1 in that, in the same way, switching pulses are supplied to the level control devices 20 and 21 via a remote control, as indicated by arrows 22 and 23, such that a corresponding adjustment of the tone signal level is effected. In addition to the two measuring points terminated by the sound transducers 24 and 25, further measuring points 28 to 32 of the same kind are indicated by broken lines as measuring points which can be connected to the tone generators 10 to 12 via the lines 13 to 15 respectively, and which correspond to the two preceding measuring points which are shown in detail. These measuring points 28 to 32 also correspond in their method of operation. The arrangement need not terminate with the measuring point 32; further measuring points can also be connected. WHAT WE CLAIM IS:

1. An audiometer comprising tone generating means, a plurality of acoustic transducers, and a plurality of signal control stages, each signal control stage including a respective semiconductor switch and being connected between an output of the tone generating means and a respective one of the transducers for controlling the level of signals supplied thereto, each signal control stage being near its respective transducer, wherein all of the transducers can be simultaneously supplied with signals from the tone generating means.

2. An audiometer according to claim 1, wherein each signal control stage further includes a switching arrangement connected between the tone generating means and the respective one of the semi-conductor switches, for switching sigrials supplied from the tone generating means.

3. An audiometer according to claim 2, wherein the tone generating means comprises a plurality of tone generators, each switching arrangement being arranged to supply its respective transducer with signals from a selected tone generator.

4. An audiometer according to any preceding claim, wherein each semi-conductor switch comprises an integrated circuit known as a digital-to-analogue converter.

5. An audiometer according to any preceding claim, wherein the signal control stages are adapted to be remotely-controlled by means of an arithmetic unit, such as a microprocessor, desk computer (programmable logic away) or process computer.

6. An audiometer according to any preceding claim, wherein each signal control stage is fitted into a housing of its respective transducer.

7. An audiometer substantially in accordance with any example herein described with reference to the accompanying drawing.