WO2020041232A1

WO2020041232A1 - Stethoscope testing device and method of use

Info

Publication number: WO2020041232A1
Application number: PCT/US2019/047142
Authority: WO
Inventors: Clifford A. Henricksen
Original assignee: Ingen6, Llc
Priority date: 2018-08-20
Filing date: 2019-08-20
Publication date: 2020-02-27

Abstract

The present invention describes a stethoscope testing device and method of using same to determine the frequency response of a given stethoscope. The device comprises a forcing device having a top surface operable to receive a stethoscope diaphragm and vibrate at a set frequency determined by a processor. The device further comprises a microphone holding block having two connectors and two recording microphones, wherein each connector is in sound communication with a recording microphone and wherein said connectors are configured to receive the eartips of a stethoscope. A processor in communication with the forcing driver and recording microphones is operable to transmit the test frequency signal to the forcing driver as well as receive and compare the audio response signal to the test frequency to measure the stethoscope's frequency response. The device may also comprise a load member to resemble hand pressures on the stethoscope head while under test.

Description

Patent Cooperation Treaty Patent Application

TITLE: STETHOSCOPE TESTING DEVICE AND METHOD OF USE

INVENT OR(S) : CLIFF HENRICKSEN

[0001] RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No.

62/719,940 filed August 20, 2018. The entire contents of the above application are hereby incorporated by reference as though fully set forth herein.

[0003] FIELD

[0004] The present invention relates in general to the field of medical devices.

More specifically, the present invention relates to devices designed to test the efficiency of stethoscopes.

[0005] BACKGROUND

[0006] A stethoscope allows the listener to hear normal and abnormal respiratory, cardiac, pleural, arterial, venous, uterine, fetal and intestinal sounds as a means of diagnosis. Most stethoscopes have the following parts: eartips, eartube, tubing, headset, stem, chest-piece, diaphragm, and a bell. Sounds from the body are passively amplified and transmitted to an air volume via the bell or a diaphragm. The diaphragm mechanism is preferred for most diagnostic applications.

[0007] The diaphragm is normally a thin structure typically made of flat or curvilinear-formed plastic material with some means of creating axial compliance so that it can have motion. The pressure waves generated by the natural functions of the patient’s internal organs will cause the diaphragm to move. The diaphragm is air-sealed to an enclosed or captive air volume which has a small hole in it leading to air tubes. The diaphragm’s motion changes the volume of captive air, thus creating an acoustic signal at the exit hole that enters the air tubes. The resulting acoustic signals are then sent via the tube assembly to the stethoscope operator’s ears.

[0008] The sensitivity of the stethoscope to convert body-borne pressures at various low frequency ranges to audio signal output is a critical performance characteristic of the device. Generally, very low frequencies (20-200 Hz) are listened to for heartbeat and midrange frequencies (200-2000 Hz) detect lung wind noise, stomach noise, and other internal organs. To date, there is no device that measures the spectral sensitivity of a stethoscope at these very important frequency ranges. Nor is there a device that targets and evaluates how hand pressures on the stethoscope head or how the material and length of the hearing tubes may affect the frequency response of a given stethoscope.

[0009] Accordingly, there is a need for a more comprehensive testing device that not only measures the frequency response of the stethoscope - that is, the efficiency of the diaphragm in converting a controlled frequency input into an audio signal - but also, evaluates how the stethoscope’s individual component parts affect the overall frequency response.

[00010] BRIEF SUMMARY OF INVENTION

[00011] The preferred embodiment of the subject stethoscope testing device comprises a forcing device having a top surface operable to receive a stethoscope diaphragm and vibrate at a set frequency determined by a processor. The device further comprises a microphone holding block having two connectors and two recording microphones, wherein each connector is in sound communication with a recording microphone and wherein said connectors are configured to receive the eartips of a stethoscope. The microphone holding block may be linearly adjusted to remove any bends or kings in the hearing tube assembly of the stethoscope, which may affect the frequency response of a given stethoscope. A processor in communication with the forcing driver and recording microphones is operable to transmit the test frequency signal to the forcing driver as well as receive and compare the audio response signal to the test frequency to measure the stethoscope’s frequency response. The device may also comprise a load member to resemble hand pressures on the stethoscope head while under test.

[00012] Another object of this invention is the method for utilizing the subject device to measure a given stethoscope’s frequency response as well as how the stethoscope’s individual component parts affect the overall frequency response.

[00013] BRIEF DESCRIPTION OF THE DRAWINGS

[00014] Figure 1. Fig. 1 shows alternative perspective views of the stethoscope testing device with a standard stethoscope in place for testing.

[00015] Figure 2. Fig. 2 shows an exploded view of the forcing device separate from its top surface.

[00016] Figure 3. Fig. 3 shows a stethoscope head of the stethoscope under test placed on the forcing device.

[00017] Figure 4. Fig. 4 shows a partial perspective view of the microphone holding block with the eartips of the stethoscope under test in place. [00018] Figure 5. Fig. 5 is a perspective view of a connector in the microphone holding block.

[00019] Figure 6. Fig. 5 is a flow diagram showing the method used by the stethoscope testing device to measure the frequency response of a stethoscope under test.

[00020] DETAILED DESCRIPTION

[00021] As seen in Fig. 1, the subject invention comprises a forcing device 10 (or “driver”) that delivers mechanical forces of a desired frequency range to the stethoscope head 15 being tested. A more detailed depiction of the forcing device 10 is shown in Figs. 2 and 3. Here, the forcing device 10 comprises a modified typical magnetic loudspeaker driver wherein a top surface 25 further comprising a rigid plate 30 (e.g. carbon fiber) is bonded to the base of the forcing device 10 and sealed along the forcing device’s 10 main cone 15 and along its outer diameter; additionally, a disc 40 of minimal thickness silicon rubber foam, or some other material that mimics human skin, is applied to the external side of the plate 30 using pressure sensitive adhesive. Typically, the forcing device 10 will communicate with an amplifier to provide the needed amperage to power the forcing device 10.

[00022] As seen in Fig. 1, the forcing device 10 is positioned within a casing 50 that further comprises a load member 55 on one end and a microphone holding block 150 on the other end. The load member 55 is preferably positioned directly above and in vertical alignment with the top surface 25 of the forcing driver 10. An example of an acceptable load member 55 is shown and comprises a tower 60 having at least one arm 70 with its distal end extending radially outward above the forcing device 10 where its distal end is capped with a linear bearing 80. Disposed within the linear bearing 80 is a vertical rod 90 that freely moves up and down above the forcing device 10. The bottom end of the rod 90 comprises a platform 35 in contact with the stethoscope head 15, wherein the platform may also be padded. The opposing top end of the rod 90 comprises a separate platform 35 operable to hold weights 120. Weights may be added to this platform to closely resemble variable hand pressures applied to the stethoscope head 15.

[00023] Turning to Figs. 1 and 4, the microphone holding block 150 comprises of two connectors 170, wherein each connector 170 is in sound communication with a corresponding recording microphone 190. The preferred connector 170 (as detailed in Fig. 5) is attached to the receiving end of the recording microphone 190 using a rubber gasket coated with epoxy to create an air-seal between the diaphragm of the measurement microphone 190 and the connector 170. Other means of attachment known in the art for creating the required air-seal may used. The connector 170 comprises an internal and fully enclosed channel that directs the audio signal from the ear tips of the stethoscope under test to the recording microphone 190. The eartips 195 of the stethoscope under test fit firmly within the beveled slots 175 on the connector 170 by means of the normal compression caused by the stiffness of the stethoscope’s natural clamping mechanism. Preferably, the adjacent connectors 170 are spaced apart approximately the same distance as the ears of a normal human being.

[00024] The device further comprises a processor (not shown) equipped with audio measurement software known in the art that is in communication with the forcing device 10 as well as the recording microphones 190. The processor is operable to transmit a test frequency signal to the forcing device 10 that will cause the forcing device 10 to deliver mechanical forces based on the test frequency to the stethoscope diaphragm. Similarly, the processor is operable to receive the return acoustical signals from the recording microphone 190. The processor will then perform a comparative analysis of the return acoustical signals against the test frequency to determine the stethoscope’s frequency response.

[00025] Another aspect of the subject testing device is the maneuverability of the microphone holding block 150. As shown in Fig. 1, the microphone holding block 150 may have a rod 180 disposed within that is in longitudinal alignment with the forcing driver 10. The microphone holding block 150 may be slidably adjusted along the length of the rod 180 to accommodate stethoscopes having variable tube lengths. For optimal efficiency, it is important that the stethoscope under test be evaluated without big bends or kinks in the sound tube assembly.

[00026] Turning to Fig. 6, a flow diagram showing the device being used to measure a stethoscope’s frequency response is shown. After the stethoscope diaphragm is placed on the top surface 25 of the forcing driver 10, and the eartips 195 are inserted into the beveled 175 slots at the connectors 170, a designated load 120 may be applied to the stethoscope head 15 using the load member 55. Next, the microphone holding block may be adjusted along the longitudinal rod 180 to remove any bends or kinks in the sound tube assembly.

[00027] After the stethoscope under test has been positioned within the device, the processor communicates with the forcing device 10, and amplifier where applicable, to transmit a test frequency to the forcing device 10. Thereafter, the forcing device 10 will excite the stethoscope head 15 and cause acoustical signals to be generated in the stethoscope’s transducer head and delivered to the ear tips 195 positioned within the beveled slots 175 of the connectors 170. These acoustical signals will be fluidly transmitted from the ear tips 195, through the connectors 170, to the recording microphones 190. Each recording microphone 190 communicates the acoustical signal back to the processor where the return acoustical signal is measured against the test frequency signal to determine the frequency response of the stethoscope.

[00028] As an additional option, the acoustical return signals from the recording microphones 190 can be electronically combined to form a composite signal, or they can be recorded separately, so the signals traveling through each individual hearing tube can be recorded and evaluated.

[00029] Additionally, as a further option for testing, the stethoscope head’s performance can be measured directly by mechanically disconnecting it from the hearing tube body and coupling its output directly to the input of the recording microphone 190 and repeating the entire process.

[00030] For the purposes of promoting an understanding of the principles of the invention, reference has been made to the preferred embodiments illustrated in the drawings, and specific language has been used to describe these embodiments. However, this specific language intends no limitation of the scope of the invention, and the invention should be construed to encompass all embodiments that would normally occur to one of ordinary skill in the art. The particular implementations shown and described herein are illustrative examples of the invention and are not intended to otherwise limit the scope of the invention in any way. For the sake of brevity, conventional aspects of the system (and components of the individual operating components of the system) may not be described in detail. Furthermore, the connecting lines, or connectors shown in the various figures presented are intended to represent exemplary functional relationships and/or physical or logical couplings between the various elements. It should be noted that many alternative or additional functional relationships, physical connections or logical connections may be present in a practical device. Moreover, no item or component is essential to the practice of the invention unless the element is specifically described as “essential” or “critical.” Numerous modifications and adaptations will be readily apparent to those skilled in this art without departing from the spirit and scope of the present invention.

Claims

CLAIMS What is claimed is:

1. A stethoscope testing device comprising: a forcing device further comprising a top surface that is operable to vibrate at a set frequency, wherein said top surface of the forcing device is configured to receive the diaphragm of a stethoscope under test; a microphone holding block further comprising two connectors and two recording microphones, wherein each connector is in sound communication with a recording microphone and wherein said connectors are configured to receive the eartips of a stethoscope; a processor in communication with the forcing driver and recording microphones, wherein said processor is operable to transmit a test frequency signal to the forcing driver and wherein said processor is operable to receive the audio response signal from the recording microphones; wherein the processor measures the frequency response of the stethoscope under test based on the test frequency signal and the audio response signal.

2. The stethoscope testing device of claim 1 wherein the forcing driver further comprises an amplifier, wherein the processor is in communication with the amplifier and the amplifier is in communication with the forcing driver.

3. The stethoscope testing device of claim 1 wherein the top surface of the forcing driver further comprises a layer of silicon rubber foam.

4. The stethoscope testing device of claim 1 further comprising a load member positioned above the top surface of the forcing driver, wherein said load member is operable to provide a downward force the diaphragm of a stethoscope under test.

5. The stethoscope testing device of claim 4 wherein the load member further comprises a fixed holding tower with linear bearings operable to receive a rod having a top and a bottom, wherein the top of the rod further comprising a platform adapted to hold weights and the bottom of the rod comprises a hold down pad, wherein the rod is positioned in vertical alignment with the radial center of the diaphragm and is allowed to oscillate above the diaphragm.

6. The stethoscope testing device of claim 1 further comprises an epoxy coated gasket between the connector and the receiving end of the recording microphone, wherein the gasket creates an air-seal between the connector and the receiving end of the recording microphone.

7. The stethoscope testing device of claim 1 further comprising a casing having a first portion and a second portion connected by a guide rod, wherein the first portion is configured to hold the forcing driver and the second portion is configured to hold the microphone holding block, wherein the second portion is operable to move longitudinally along the guide rod.

8. The stethoscope device of claim 7 wherein the second portion is operable to be removed from the first portion to prevent bending or kinks in the sound tube assembly of the stethoscope under test.

9. A method for testing a stethoscope, said method comprising the steps of: a. providing a stethoscope; b. providing a stethoscope testing device comprising: a forcing device further comprising a surface that is operable to vibrate at a set frequency, wherein said top surface of the forcing device is configured to receive the diaphragm of a stethoscope under test; a microphone holding block further comprising two connectors and two recording microphones, wherein each connector is in sound communication with a recording microphone and wherein said connectors are configured to receive the eartips of a stethoscope; a processor connected to the forcing driver and recording microphones, wherein said processor is operable to transmit a frequency signal to the forcing driver and wherein said processor is operable to receive the audio signal from the recording microphones; wherein the processor measures the frequency response of the stethoscope under test. c. placing the diaphragm of the stethoscope on the surface of the forcing driver; d. connecting the eartips of the stethoscope to the connectors in the microphone holding block; e. transmitting a test frequency signal from the processor to the forcing driver; f. having the processor receive the response audio signal from the recording microphones; and g. determining frequency response of the stethoscope under test.

10. The method of claim 9 further comprising the step of providing a load member to the stethoscope testing device, wherein the load member is positioned above the top surface of the forcing driver, and wherein said load member is operable to provide a downward force the diaphragm of a stethoscope under test;

11. The method of claim 10 further comprising the step of adding weights to the load member.