Programmable audio level control useful in audiometric apparatus

Claim 2

In an audiometric circuit, in combination: a. tone generator means operable to supply in a selected sequence each of a plurality of tone signals in the audio frequency range; b. logarithm circuit means connected to said tone generator means and adapted to receive and produce from each said selected tone signal an output signal representing the logarithm thereof; c. a continuous control voltage source productive of a ramp voltage wave controllable as to ascending and desCending direction and representing a control voltage having a maximum and minimum values when moving in either direction and being selected to produce a predetermined proportional acoustically produced decibel range in the audiometric circuit output; d. first circuit means connected to continuously combine the output of said logarithm circuit means and said voltage source and to continuously produce therefrom an exponentiated signal representing the anti-log of the combined logarithm signal and voltage wave; e. voltage control means connected to said voltage source and adapted for operation by the patient being tested to reverse on each occasion of operation by the patient the direction in which said ramp wave is being generated to cause the audiometric circuit decibel output to have a simultaneous preselected change in direction of ascending or descending of decibel level; and f. second circuit means connected to receive said exponentiated signal and produce an output hearing test signal having precisely controlled gain qualities in linear proportion to said control voltage and at the selected said audio frequency.

Claim 3

In a circuit as claimed in claim 1 wherein said test signal when heard through an earphone by the patient in conjunction with recording the output of said voltage control in coordination with the operation of said voltage control means by the patient provides an indication of the patient''s hearing loss.

Claim 4

In a circuit as claimed in claim 1 wherein said first circuit means includes: a. summing circuit means connected to combine the output of said logarithm circuit means and said voltage source and to produce therefrom a summed signal representing the sum of said logarithm signal and said voltage wave, and includes b. exponential circuit means connected to said summing means and adapted to produce from said summed signal an exponentiated signal representing the anti-log of said combined logarithm signal and voltage wave and said second circuit means includes filter means connected to receive said exponentiated signal and remove the direct current component thereof.

Claim 5

In an audiometric circuit as claimed in claim 3 including a second summing circuit means connected between said tone generator means and logarithm circuit means and a constant voltage source connected to said second summing circuit means, said second summing means being adapted to sum the output of said tone generator and that of said constant voltage source and produce as an input signal for said logarithm circuit means a signal whose voltage value is always greater than zero volts.

Claim 6

In an audiometric circuit as claimed in claim 3 wherein said logarithm circuit, first and second circuit means each comprise solid state circuit means.

Claim 7

In an audiometric circuit as claimed in claim 3 wherein: a. said logarithm circuit comprises a diode; b. said control voltage source comprises a ramp generator; c. said summing circuit means comprises a solid state computing amplifier; d. said voltage control comprises manually operated electrical switching means; e. said exponential circuit means comprises a diode and computing amplifier; and f. said filter means comprises a resistor-capacitor parallel network.

Claim 8

In an audiometric circuit as claimed in claim 3 wherein said tone generator means includes tone interrupter means to form each said audio frequency into a train of pulses.

Claim 9

In an audiometric circuit as claimed in claim 1 including a second summing circuit means connected between said tone generator means and logarithm circuit means and a constant voltage source connected to said second summing circuit means, said second summing means being adapted to sum the output of said tone generator and that of said constant voltage source and produce as an input signal for said logarithm circuit means a signal whose voltage value is always greater than zero volts.

Claim 10

In an audiometric circuit as claimed in claim 1 wherein said tone generator means produces a signal of unchanging polarity and greater than zero volts.

Claim 11

In an audiometric circuit as claimed in claim 1 wherein said logarithm circuit, first and second circuit means each comprise solid state circuit means.

Claim 12

In an audiometric circuit as claimed in claim 1 wherein said tone generator means includes tone interrupter means to form each said audio frequency into a train of pulses.

Claim 13

In an audiometric circuit as claimed in claim 1 wherein said voltage source comprises a linear ramp generator.

Claim 14

In an audiometric circuit as claimed in claim 1 including amplitude control means connected to said voltage source and voltage control means and being effective at the onset of each said tone to cause the amplitude rate of change of said tone signal to gradually and smoothly decrease according to a programmed sequence.

Claim 15

In an audiometric circuit as claimed in claim 9 wherein said amplitude control means comprises a decaying voltage source means.

Claim 16

In an audiometric circuit as claimed in claim 1 wherein said first circuit means includes tone interrupter means to form each said audio frequency into a train of pulses.

Claim 17

In a circuit as claimed in claim 1 wherein each said test signal when heard through an earphone by the respective patients in conjunction with recording the output of respective said voltage controls in coordination with the operation of respective said voltage control means by the patient provides an indication of each patient''s hearing loss.

Claim 18

In a circuit as claimed in claim 1 wherein each said first circuit means includes: a. summing circuit means connected to combine the output of said logarithm circuit means and the respective said voltage source and to produce therefrom a summed signal representing the sum of said logarithm signal and the respective said voltage wave, and includes b. exponential circuit means connected to said summing means and adapted to produce from said summed signal an exponentiated signal representing the anti-log of said combined logarithm signal and respective voltage wave and each said second circuit means includes filter means connected to receive said exponentiated signal and remove the direct current component thereof.

Claim 19

In an audiometric circuit as claimed in claim 17 wherein: a. said logarithm circuit comprises a diode; b. each said control voltage source comprises a ramp generator; c. each said summing circuit means comprises a solid state computing amplifier; d. each said voltage control comprises manually operated electrical switching means; e. each said exponential circuit means comprises a diode and computing amplifier; and f. each said filter means comprises a resistor-capacitor parallel network.

Claim 20

In an audiometric circuit as claimed in claim 3 wherein said logarithm circuit, first and second circuit means each comprise solid state circuit means.

Claim 21

In an audiometric test circuit, in combination: a. a tone generator operable to supply in a selected sequency each of a plurality of tone signals in the audible range; b. a continuous control voltage source productive of a ramp voltage wave controllable as to ascending and descending direction and representing a control voltage having maximum and minimum values when moving in either direction and being selected to produce a predetermined proportional acoustically produced decibel range in the audiometric circuit output; c. voltage control means connected to said voltage source and adapted for operation by the patient being tested to reverse on each occasion of operation by the patient the direction in which said ramp wave is being generated; and d. circuit attenuator means connected to said tone generator and to said control voltage source and being adapted to generate from the output of said generator and control voltage source an output test signal having precisely controlled gain qualities in proportion to said control voltage and at the selected saiD frequency, said test signal when connected to be received in a selected earphone in conjunction with recording the output of said control voltage source in coordination with operation of said voltage control means by the patient providing an indication of the hearing loss of said patient.

Claim 22

In an audiometric test circuit, in combination: a. a tone generator operable to supply in a selected sequency each of a plurality of tone signals in the audible range; b. a continuous control voltage source productive of a ramp voltage wave controllable as to ascending and descending direction and representing a control voltage having maximum and minimum values when moving in either direction and being selected to produce a predetermined proportional acoustically produced decibel range in the audiometric circuit output; c. voltage control means connected to said voltage source and adapted for operation by the patient being tested to reverse on each occasion of operation by the patient the direction in which said ramp wave is being generated; and d. circuit attenuator means connected to said tone generator and to said control voltage source and being adapted to generate from the output of said generator and control voltage source an output test signal having precisely controlled gain qualities in proportion to said control voltage and at the selected saiD frequency, said test signal when connected to be received in a selected earphone in conjunction with recording the output of said control voltage source in coordination with operation of said voltage control means by the patient providing an indication of the hearing loss of said patient.

Claim 23

In an audiometric test circuit as claimed in claim 20 wherein said voltage source comprises a linear ramp wave generator and said output test signal is in linear proportion to said control voltage.

Claim 24

In an audiometric test circuit as claimed in claim 20 including amplitude control means connected to said voltage source and voltage control means and being effective at the onset of each said tone to cause the amplitude rate of change of said tone signal to gradually and smoothly decrease according to a programmed sequence.

Claim 25

In an audiometric circuit, in combination: a. tone generator means operable to supply in a selected sequence each of a plurality of tone signals in the audio frequency range; b. logarithm circuit means connected to said tone generator means and adapted to receive and produce from each said selected tone signal an output signal representing the logarithm thereof; c. a plurality of continuous control voltage sources each of which is productive of a ramp voltage wave controllable as to ascending and descending direction and representing a control voltage having a maximum and minimum values when moving in either direction and being selected to produce a predetermined proportional acoustically produced decibel range in the audiometric circuit output; d. a plurality of first circuit means connected to continuously combine the output of said logarithm circuit means and each said voltage source and to continuously produce therefrom exponentiated signals representing the anti-log of the said logarithm signal combined with each of said voltage waves; e. a plurality of voltage control means connected to each said voltage source and each being adapted for operation by the respective patient being tested to reverse on each occasion of operation by the patient the direction in which said ramp wave is being generated to cause the respective audiometric circuit decibel output to have a simultaneous pre-selected change in direction of ascending or descending of decibel level; and f. a plurality of second circuit means connected to receive said exponentiated signal and produce an output hearing test signal having precisely controlled gain qualities in linear proportion to said control voltage and at the selected said audio frequency.

Claim 26

In an audiometric circuit, in combination: a. tone generator means operable to supply in a selected sequence each of a plurality of tone signals in the audio frequency range; b. logarithm circuit means connected to said tone generator means and adapted to receive and produce from each said selected tone signal an output signal representing the logarithm thereof; c. a plurality of continuous control voltage sources each of which is productive of a ramp voltage wave controllable as to ascending and descending direction and representing a control voltage having a maximum and minimum values when moving in either direction and being selected to produce a predetermined proportional acoustically produced decibel range in the audiometric circuit output; d. a plurality of first circuit means connected to continuously combine the output of said logarithm circuit means and each said voltage source and to continuously produce therefrom exponentiated signals representing the anti-log of the said logarithm signal combined with each of said voltage waves; e. a plurality of voltage control means connected to each said voltage source and each being adapted for operation by the respective patient being tested to reverse on each occasion of operation by the patient the direction in which said ramp wave is being generated to cause the respective audiometric circuit decibel output to have a simultaneous pre-selected change in direction of ascending or descending of decibel level; and f. a plurality of second circuit means connected to receive said exponentiated signal and produce an output hearing test signal having precisely controlled gain qualities in linear proportion to said control voltage and at the selected said audio frequency.

Claim 27

In an audiometric circuit as claimed in claim 23 including a second summing circuit means connected between said tone generator means and logarithm circuit means and a constant voltage source connected to said second summing circuit means, said second summing means being adapted to sum the output of said tone generator and that of said constant voltage source and produce as an input signal for said logarithm circuit means a signal whose voltage value is always greater than zero volts.

Claim 28

In an audiometric circuit as claimed in claim 23 wherein said tone generator means produces a signal of unchanging polarity and greater than zero volts.

Claim 29

In an audiometric circuit as claimed in claim 23 wherein said logarithm circuit, first and second circuit means each comprise solid state circuit means.

Claim 30

In an audiometric circuit as claimed in claim 23 wherein each said first circuit means includes tone interrupter means to form each said audio frequency into a train of pulses.

Claim 31

In an audiometric circuit as claimed in claim 23 wherein each said voltage source comprises a linear ramp generator.

Claim 32

In an audiometric circuit as claimed in claim 23 including amplitude control means connected to each said voltage source and voltage control means and being effective at the onset of each said tone to cause the amplitude rate of change of said respective tone signal to gradually and smoothly decrease aCcording to a programmed sequence.

Claim 33

In an audiometric circuit as claimed in claim 29 wherein said amplitude control means comprises a decaying voltage source means.