GB2030753A - Audiometer - Google Patents

Abstract

An audiometer comprising a sound generator (1, 2) with a variable output frequency, a volume control (3, 4) and an automatic display means (11) for the audibility threshold values established by the person being tested, by operating a switch (12), in which the display means (11) includes a matrix of light emitting diodes actuated by a microcomputer (6) which controls the sound generator (1, 2) and the volume control (3, 4) in dependence on the actuations of the switch by the person being tested. <IMAGE>

Description

SPECIFICATION Audiometer The present invention relates to an audiometer comprising a sound generator with a variable output frequency, a volume control and an automatic display means for the audibility threshold values established, which can be influenced by the person being tested, by means of a switch.

An audiometer of this kind is already known. This known device essentially comprises a motor, and a transmission means connected to the output of the motor and having a drive shaft for advancing a strip of paper and also continuously increasing or reducing the frequency of the sound generator.

A further drive shaft of the transmission means is provided for driving a turning transmission means by way of which the volume control of the sound generator and the marking pen which is connected to the volume control and which slides over the strip of paper are movable. The turning transmission means is reversed by means of a switch which is actuated by the person being tested, depending on whether that person hears a testing sound or not.

The disadvantage of this known audiometer is that the progress of the operation of measuring the subject's hearing cannot be influenced by the person being tested as the change in frequency depends solely on the speed of rotation of the motor, which cannot be controlled by the subject being tested, and the transmission ratio of the transmission means, which also cannot be controlled. This very often gives rise to problems as the speed should be slow, for reasons concerned with the accuracy of the test result, but on the other hand a long test period results in the subject suffering from fatigue, which again causes the degree of accuracy of the test result to suffer.In addition, it is only possible for the frequency to be continuously altered in one direction so that it is only possible to examine the subject once at each frequency in a test, and errors on the part of the subject being tested, for example an excessively slow reaction when the test sound is observed or when the subject can no longer hear the test sound, are fully incorporated into the test result as the marking pen continues to write throughout the whole period of the test and in so doing records a band which is of greater or lesser width and which is formed by a zig-zag line, with the audibility threshold of the subject being tested extending approximately at the centre of the above-mentioned band.In addition, it is not possible for the ear of the subject in respect of which the hearing is not to be measured to be made deaf with a very high degree of accuracy, as must be done in dependence on the ear to be measured.

Recent discoveries have shown that, with regard to the degree of accuracy of the measuring operation, it is substantially more advantageous for the subject being tested to be given individual frequencies, not in a uniform sequence but in a mixed sequence, which is impossible with the known audiometer.

Hitherto, this latter was possible only with the known audiometers which are to be operated by a skilled person conducting the test and in which both every frequency and also the acoustic pressure must be set manually.

The limit value of audibility or acoustic pressure, as determined by repeatedly increasing and reducing the acoustic pressure at a given frequency, is recorded on a graph or diagram.

Although this manual method makes it possible for the speed at which the test is conducted to be adapted to the subject being tested, nonetheless it is in no way possible to exclude the possibility of errors when the measurement values are entered in the graph, and a suitably skilled person is required for every test. With the manual method it is possible to adjust the degree of 'deafening' of the other ear, to a high degree of accuracy, on the basis of the respective values measured, but very complicated calculations are required for this purpose.

The aim of the present invention is to provide an audiometer with an automatic test procedure and recording of the measurement results, wherein the test result can be issued or transferred in the form which is usually found in manual audiometry, in which respect the possibility of transfer errors is to be practically excluded. In addition, the invention seeks to provide that the test procedure can be substantially influenced by the person being tested and can be performed at fixed frequencies, while the sequence in which the individual frequencies are emitted can be freely established.

According to the invention, this is achieved in that the display means includes a multiplicity of punctiform light sources which are arranged in a grid pattern and which can be actuated by way of a microcomputer which controls the sound generator and the volume control in dependence on the actuations of the switch by the person being tested.

In this way it is possible for a diagram or graph as was hitherto conventionally used and which is more advantageously printed on transparent paper or which is provided with punched holes at the points of intersection of the grid pattern which symbolises the frequencies and acoustic pressures to be laid over the light sources which are formed for example by small incandescent lamps or even better by light-emitting diodes, and for the diagram to be marked in a manner corresponding to the light sources which are actuated and which thus emit light, with virtually no fear of errors in this operation.

Furthermore, it is also possible for the display means to be in the form of a picture tube, wherein suitable control of the electron beam deflection means can cause different points of the screen, which are on a grid pattern, to be illuminated, which points, as described above, can be easily transferred to the usual graphs or diagrams, without the possibility of error. The resolution of the pattern can be selected as desired and can be adapted to the parameters of the audiometer.

Using a microcomputer also makes it possi ble however, by suitable programming, for fixed frequencies to be emitted in any desired sequence and for the test program to be run through, in dependence on the subject being tested. Thus, the programming can provide that, after the switch has been actuated a given number of times by the person being tested, within a given tolerance range in respect of the acoustic pressure, the test is switched over to the next frequency. In addition, the programming can also provide that, on the basis of the values detected, the other ear of the person being tested may be made deaf to the optimum extent, in accordance with the known guidelines, which is very important particularly with highly different degrees of deafness, in order to avoid falsification of the test result.

Using a microcomputer system also makes it possible for the data produced to be stored and to be recalled after the entire test has been concluded or to be transferred to peripheral equipment such as printers, memories or the like, while additional data, for example details concerning the subject being tested, can also be passed to the peripheral equipment.

It is also possible for other hearing tests to be carried out, by an enlarged program.

In order to construct the apparatus of the invention at low cost in respect of the circuitry involved, it is advantageous for the light sources preferably to be in the form of lightemitting diodes and connected in a matrix, in which case the mutually parallel control lines of the matrix are more advantageously each connected to a respective 1 out of n-decoder.

A particularly preferred embodiment of the invention provides in this connection that the outputs of the one 1 out of n-decoder can be successively activated by actuation by way of the central control unit of the microcomputer and selection of the light source corresponding to the valve to be displayed is effected synchronously with respect to activation of the decoder outputs, by actuation of the second 1 out of n-decoder, by means of the central control unit of the microcomputer.

This arrangement provides that there is only ever one light source, in particular a lightemitting diode, which is briefly actuated so that it can be operated at a relatively high current load value and shines brightly. Switching over from one light-emitting diode to the next can occur so rapidly in this arrangement that the human eye has the impression that all the actuated light-emitting diodes were illuminated simultaneously.

The invention will now be described in greater detail with reference to the drawings, in which: Figure 1 shows a block circuit diagram of the audiometer according to the invention, and Figure 2 shows a block circuit diagram of the means for actuating the display arrangements.

The audiometer according to the invention essentially comprises the two signal generators 1 and 2, the volume controls or acoustic pressure setting means 3 and 4 which are associated with the signal generators 1 and 2, and the selector switch 5 for side selection, al of which components, like the display means 11, are connected to a microcomputer 6 and are controlled thereby. The audiometer further includes the end stages 7 and 8 which are connected to the selector switch 5, and the associated earphones 7' and 8', and operating elements 9 by means of which it is possible to intervene in the test procedure or to carry out manual audiometry, and the switch 12 which is provided for use by the subject being tested.

This arrangement makes it possible, in the optimum manner for the test procedure to be performed in consideration of the reaction of the subject being tested. By means of suitable programming, it is possible, for example for establishing the threshold of audibility, for the acoustic pressure of a sound at a given freqency to be increased and reduced several times until the subject being tested has actuated the switch 12 a given number of times, within a tolerance band, whereupon the apparatus is switched over to a different frequency.

At the same time, on the basis of the measurement value which is determined in this way, the necessary degree of deafening is determined by the microcomputer and the acoustic pressure setting means 4 of the second signal generator 2 which in this case produces a so-called 'deafening noise' can be suitably adjusted.

The measurement values detected in respect of the-threshold of audibility at the various frequencies can be displayed immediately in visible form by the display means 11 or they can be put into intermediate storage by the microcomputer 6 and can be displayed altogether after a suitable command has been given, by means of the operating elements 9.

Actuation of the display means 11 which, as shown in Fig. 2, is formed by light-emittinri diodes 110 which are arranged in a matrix and whose parallel control lines 111 and 111' can be actuated by way of driver stages 11 2 and 11 2'. The driver stages 112 and 112' respectively are connected to 1 out of n-decoders 63 and 62 respectively which, in the embodiment illustrated, are in the form of 1 out of 32-decoders or 1 out of 16decoders, which in turn are each connected by way of the input-output port 61 to the central control unit 60 of the microcomputer 6; other components belonging to microcomputer 6, such as for example writing-reading memories which can be provided for example for temportarily storing data, fixed-value memories for storing the program, further inputoutput units or the like are connected to the central control unit 60.

In this arrangement, the display is effected in the following manner: under the control of the program, one of the 16 outputs of the 1 out of 16-decoder is activated and set to the level H whereby one of the drivers 11 2 for the control lines 111 is caused to conduct. In addition, the output of the 1 out of 32decoders 62 is activated and set to the level L which corresponds to that light-emitting diode 110 which represents the value to be displayed. This causes the driver 112' for the corresponding control line 111' to conduct and the light-emitting diode 110 at the corresponding point of intersection of the matrix to be illuminated. This light-emitting diode remains switched-on for a predeterminable period of time, and the microcomputer which advantageously operates in a time-multiplexing mode carries out in the meantime other tasks which it is to perform.

After this period of time has expired, the central control unit 60, under the control of the program, activates the next following output of the 1 out of 16-decoder 63. This causes the next following driver to become conducting. In addition, the output of the 1 out of 32-decoder 62 which corresponds to the light-emitting diode of that control line, which is to be actuated, is activated. This light-emitting diode 110 also remains switched on for the predeterminable period of time. The apparatus is then switched on to the next control line 111. After the last column, this process is continued in the first column.

If a plurality of diodes 110, for example 2 of a control line 111 are to be lit, it is possible to provide two sweeps, in which case the first light-emitting diode is activated in the first sweep and the second light-emitting diode is activated in the second sweep. In this arrangement, the predeterminable time in respect of each light-emitting diode is desirably reduced, in order to avoid optical flicker.

In order to transfer the measurement values on to the diagram or graph which has hitherto been usually employed in audiometry operations and on which the audibility threshold is recorded at the various frequencies, the graph form which is more desirably printed on transparent paper only needs to be laid on to a glass plate which covers the light-emitting diodes 110 or other light sources, so that the lit diodes can be marked. There is virtually no possibility of error in transferring the measurement values in this way.

It will be appreciated that graph forms which are printed on opaque paper can also be used, if they are provided with apertures which correspond to the light-emitting diodes, when the form is laid thereover, in which case each light-emitting diode 110 is arranged at the point of intersection of two imaginary lines which symbolise a frequency or a value in respect of the acoustic pressure and which are more desirably printed on the graph form.

The measurement result is available in digital form, so that it is possible for the result to be transferred to peripheral equipment such as printers, memories or the like, in which case additional data can also be transferred therewith.

However, by suitable actuation of the operating elements 9 which can be of a very simple construction, for example in the form of pushbuttons, the audiometer according to the invention can also be used for manual audiometry operations, in which case there is no longer any need for the operation of setting frequency and acoustic pressure, this being an operation which, over a long period of time, is fatiguing when using the previously known audiometers which can only be operated manually, as, with the audiometer of the invention, it is only necessary to press a button to give the microcomputer the order to increase or reduce for example the acoustic pressure. In addition, there is no longer any need for the complicated operation of calculating the deafening acoustic pressure as this can be established and adjusted by means of the microcomputer 6, in spite of manual operation of the audiometer.

Claims (6)

1. An audiometer comprising a sound generator with a variable output frequency, a volume control and an automatic display means for the audibility threshold values established, which can be influenced by the person being tested, by means of a switch, characterised in that the display means (11) includes a multiplicity of punctiform light sources (110) which are arranged in a grid pattern and which can be actuated by way of a microcomputer (6) which controls the sound generator (1, 2) and the volume control (3, 4) in dependence on the actuations of the switch by the person being tested.

2. An audiometer according to claim 1 characterised in that the light sources, preferably light-emitting diodes (110), are connected in a matrix.

3. An audiometer according to claim 2 characterised in that the mutually parallel control lines (111, 111') of the matrix are respec tively connected to a 1 out of n-decoder (62, 63).

4. An audiometer according to claim 2 and claim 3 characterised in that the outputs of the one 1 out of n-decoder (63) can be successively activated by actuation by way of the central control unit (60) of the microcomputer (6) and selection of the light source (110) corresponding to the value to be displayed is effected synchronously with respect to said activation of the outputs by actuation of the second 1 out of n-decoder (62), by the central control unit (60) of the microcomputer.

5. An audiometer according to claim 3 or claim 4 characterised in that transistors (112, 112') acting as drivers are connected between the outputs of the decoders (62, 63) and the control lines (111, 111 ').

6. An audiometer substantially as described herein with reference to and as shown in the drawings.