in fig1 the reference numeral 1 denotes a tone generator which is connected via a level selector 2 and a selector switch 3 for the actuation of one of the several acoustic transducers 4 to 6 . to transmit the test sound to a person to be tested there are available an earphone 4 to be applied to the ear , a vibrator 5 which transmits acoustic vibrations to the skin , and a loudspeaker 6 . the particular function of the modules 1 to 3 of the audiometer is determined by means of the data memories 7 to 9 . the current value of adjustment is then visible on the alphanumeric display panels 10 to 12 . to set the audiometer , signals are transmitted by a computer ( not shown ) via lines 17 and 18 , the signals passing from address decoders 13 to 15 into the memories 7 to 9 , respectively . to avoid interference it is assumed that the associated address is disconnected after a minimum hold time , which is longer than the expected duration of the interference . during the time that an address associated with the respective decoder 13 to 15 to be addressed is present , a reply signal coming from one of these decoders 13 to 15 is transmitted to the computer via an or gate 16 and an optocoupler 19 . 1 . optocouplers 17 . 1 and 18 . 1 are provided in the control lines 17 and 18 , respectively , in order to obtain a d - c isolation of the computer from the audiometer . here line 17 as well as the continuation line 7 . 1 for data transmission may be laid out sevenfold . also the line 1 . 1 between the memory 7 and the tone generator 1 , the line 2 . 1 between the memory 8 and the level selector 2 , as well as the line 3 . 1 between the memory 9 and the selector switch 3 may , in adaptation to the requirements of the control modules 1 to 3 , be laid out sevenfold . with the sevenfold layout corresponding to line 17 , the number of decoders 13 to 15 and of data memories 7 to 9 can be increased to 128 . in fig2 the reference numerals 20 and 21 denote blocks which invert the signals coming from the computer . these signals , as well as those of lines 7 . 3 , then go to a nand gate 22 , where they are evaluated . to eliminate the effect of interference pulses , the output signal of this gate then goes to an integrator 23 and via schmitt trigger inverters 24 and 25 to an output line 25 . 2 . a line 25 . 1 branches off from the output of inverter 24 and leads to a monostable multi - vibrator 26 which , for a certain period in the order of 20 msec to 0 . 2 sec , furnishes a control signal on line 26 . 1 for interference blanking . this signal on line 26 . 1 controls a switch which disconnects the output signal of the level selector 2 . line 25 . 2 is connected to the respective memory 7 to 9 . line 25 . 3 , branching off between the inverters 24 and 25 , carries the reply signal to the or gate 16 . fig3 shows a bit pattern memory 30 for test values which are determined by the audiometer itself . such a signal pickup may represent , e . g ., the time period between the beginning of a stimulus and the associated depression of a response key by the test subject . an and gate 31 is connected to the memory 30 via a line 30 . 1 . a second input of this and gate is supplied the reply signal of decoder 33 via line 33 . 1 . thus a reply signal is supplied to the or gate 16 via line 31 . 1 only when a ) the address associated with decoder 33 is present and b ) the memory output line 30 . 1 carries a &# 34 ; 1 &# 34 ; bit of the bit pattern memory 30 . if this is not the case , the computer receives no reply signal when it transmits the address of decoder 33 . similarly , the reply signal of decoder 34 is forwarded to the or gate 16 only when another output line 30 . 2 of the memory 30 is high . as indicated by dashed lines 35 in fig3 additional memory locations of the memory 30 , receiving the bit pattern to be transmitted to the computer , can influence the forwarding of the reply signals from additional decoders ( omitted in the drawing ), with the aid of additional and gates ( not shown ), to the or gate 16 via one of the lines 36 . by serial selection of all address decoders which are associated with the memory 30 , the computer can poll the bit pattern . line 37 leads to the computer via the optocoupler 19 . 1 . fig4 illustrates an arrangement where a first address and a first data word define a sub - address , where a second data word is stored by means of a second address . this takes place when a store command is transmitted by signals from the computer , via the lines 7 . 2 and 13 . 2 , a decoder 40 and a line 40 . 1 , to a memory 41 . this memory 41 controls the transmission of store commands of a decoder 44 which are passed to command memories 45 and 46 via lines 41 . 1 and 41 . 2 as well as by and gates 42 and 43 . the dashed lines 41 . 3 indicate the possible expansion by additional further and gates and memories . the forwarding of the stored control signals to modules such as the tone generator 1 or level selector 2 , etc ., occurs via lines 47 and 48 . the arrangement according to fig5 achieves a high immunity to interference in that all commands intended for the memory 56 are first temporarily stored in the memory 52 and then stored permanently only after coincidence with a repeat of the address and data word . to this end , decoders 50 and 51 are connected with and receive signals from the computer via lines 7 . 2 and 13 . 2 . from decoder 50 a store command passes to a memory 52 and from there to a comparator 53 . the respective valid data word transmitted on the seven lines 7 . 1 is also supplied to the comparator 53 . the comparator 53 and the decoder 51 are connected to an and gate 55 via lines 53 . 1 and 51 . 1 , respectively . thus the memory 56 receives a store command only when ( a ) the comparator 53 signals coincidence of the stored data word with the one just then present on the bus and ( b ) decoder 51 generates a store command . control signals can be sent to the modules via a line 57 . fig6 shows a multi - pole reversing switch 62 which can switch bit patterns onto the lines 17 to 18 of fig1 in place of a computer . either an address word or a data word can be selected by the eight - pole switch 60 ( two hexadecimal switches ) or the seven - pole switch 61 , respectively . these words can be sent alternately through the switch 62 to the data and address bus consisting of the lines 17 and 18 . a given command is terminated always by a data word and not by an address word . the line 18 is supplied only by the address selector 60 . in fig7 are illustrated a permanently wired address coder 70 , a data word switch 71 , and a multi - pole reversing switch 75 . a separate one of each of these devices is provided for each audiometer module to be controlled , so as to be able to operate with manual control instead of computer control . the switch arm 75 , which , as indicated by an arrow 76 , is biased into the off position by a spring , operates in such a way that it is possible to switch from the off state via the command present at the switching points 73 and via the address present at the switching points 72 again to the command also present at the switching points 74 and back to the off state , a command operation being terminated always with a command and not with an address . a mechanical , electrical or electronic interlock prevents errors from being caused by simultaneous operation of several such switches . the switching arm 75 is connected with lines 17 , 18 of fig1 line 18 being connected only to the address coder 70 . there has thus been shown and described a novel computer interface for an audiometer which fulfills all the objects and advantages sought therefor . many changes , modifications , variations and other uses and applications of the subject invention will , however , become apparent to those skilled in the art after considering this specification and the accompanying drawings which disclose the preferred embodiments thereof . all such changes , modifications , variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only the claims which follow :
an interface unit for measuring instruments , such as audiometers , which are controlled by a computer , the interface unit being as cost - efficient as possible and setting minimum requirements for the computer hardware and software . this is achieved in that the lines of the interface unit that are connected to the computer contain d - c isolating couplers and are respectively connected with individual decoders which , in turn , are connected to memories . control lines lead from these memories to the measuring modules of a measuring instrument . such a measuring instrument is usable , in particular , as an audiometer or for establishing the optimum adjustment of a hearing aid to compensate certain hearing impairments .