WO2021229318A1

WO2021229318A1 - A method to determine end of service life for earmuff cushions

Info

Publication number: WO2021229318A1
Application number: PCT/IB2021/052853
Authority: WO
Inventors: Caroline M. Ylitalo; William B. Kolb; Frank T. HERFORT; Kandyce M. Bohannon; Patrick HJORT; Kui Chen-Ho; Tien Yi T. H. WHITING; Ambuj SHARMA; Corey J. Radloff; Caitlin E. MEREE
Original assignee: 3M Innovative Properties Company
Priority date: 2020-05-13
Filing date: 2021-04-06
Publication date: 2021-11-18

Abstract

A method for determining end of service life for cushions of earmuff style auditory protection devices is described. The exemplary method comprises the steps of determining a wear parameter related to a degradation in a physical characteristic of the cushion of the auditory protection device; comparing the wear parameter to a threshold value; and making a determination based on the threshold value if the cushion has reached an end of its service life.

Description

A METHOD TO DETERMINE END OF SERVICE LIFE FOR EARMUFF CUSHIONS

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method for determining if the cushions of earmuff style auditory protection devices have reached the end of their service life and should be replaced.

Background

Auditory protection devices or hearing protectors are typically used in noisy environments to protect a wearer’s hearing from potentially harmful noise levels. One exemplary type of auditory protection device is an earmuff style hearing protector which has two connected muffs or cups that cover the wearer’s ears. Each cup further typically is formed by a rigid shell that is furnished with a noise dampening material, for example a foamed material, and soft ear cushions that fit around the ear.

The ear cushions are designed to form a seal against the wearer’s head and decrease the pressure exerted by the device on the wearer. Because the cushion contacts the wearer when worn, moisture, oils, and dirt present on the user can be transferred to the cushion. To facilitate cleaning and to protect against degradation of the foam, the cushion often includes a protective skin covering the foam. Even with the protective skin, the ear cushions and foam inserts can degrade over time resulting in diminished levels of auditory protection. Conventional practice is to replace these parts based on the time since they were placed into service. For example, a “use by” date is stamped or written on the cushion when it is installed in the cups of the auditory protection device. However, this practice does not factor the actual usage time and environment.

Therefore, there is a need for a simple method to allow the end user to determine the end of service life of the cushions for earmuff style hearing protectors.

SUMMARY

The present invention relates to a method for determining if the cushions of earmuff style auditory protection devices have reached the end of their service life. In a first embodiment, the exemplary method comprises the steps of determining a wear parameter related to a degradation in a physical characteristic of a cushion of the auditory protection device; comparing the wear parameter to a threshold value; and making a determination based on the threshold value if the cushion has reached an end of its service life.

BRIEF DESCRIPTION OF THE DRAWINGS

Figs. 1 A and IB show schematic diagrams of an exemplary auditory protection device. Fig. 2 is a flow diagram illustrating a method to determine the end of service life for a component of an auditory protection device according to the present invention.

Figs. 3 A and 3B are photographs of a new and used cushions for an auditory protection device, respectively.

Figs. 4A and 4B show images the new cushion and used cushions of Figs. 3 A and 3B after image analysis to find the wear parameter for a component of an auditory protection device according to the present invention.

Fig. 5 is a schematic representation of an exemplary test method to determine a wear parameter for a component of an auditory protection device according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention can be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “forward,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments can utilize structural or logical changes without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

In some cases, the degradation to the ear cushions and foam inserts may result from deplasticization of the skin layer on the ear cushion which can cause an increase in the glass transition temperature (Tg) and a reduction in flexibility of the skin layer material. This can cause a poor seal around an ear lowering the noise reduction performance of the auditory protection device. In other cases, degradation can occur in the foam portion of the ear cushion due to plasticizer migration into the foam or deformation or breaking down in the foam portion of the cushion.

Figs. 1 A and IB show a auditory protection device 100 having two earmuffs or cups 110 that are fixed to the ends of headband 120 and the schematic cross-section of an earmuff, respectively. The headband 120 resiliently holds the earmuffs 110 against a wearer’s ears. The earmuffs include an ear cup 112 and an annular cushion 115 attached around the open edge 113 of the ear cup. The ear cup can be made of a rigid plastic, a gas filled cellular material, or other material that absorbs sound and attenuates noise, e.g., inhibits and preferably prevents sound waves, from reaching the ear canal of the user. Annular cushion 115 seals the earmuff 110 around the ear of the user and dampens the pressure exerted by the hearing protective device 100 against the wearer’s head. The annular cushion defines an aperture 116, which accommodates the ear of a user. The annular cushion can be of any suitable shape including, e.g., oval, round, square and rectangular, and can define an aperture having any suitable shape including, e.g., oval, round, square and rectangular. The annular cushion can comprise a foam portion 117 and a skin layer 118 surrounding the foam portion. Foam portion 117 can comprise a closed cell foam, an open cell foam, or combinations thereof, and can exhibit a variety of properties including, e.g., viscoelasticity, high resiliency, and combinations thereof. Useful foam compositions include, e.g., polyurethanes, polyolefins, melamine, polyvinyl chloride, and combinations thereof. Preferably, the annular cushion exhibits instantaneous recovery.

Skin layer 118 can be a film, a woven fabric, a nonwoven web or a coating that protects the integrity of the foam portion, inhibit soiling of the foam, and enhance the cleaning properties of the cushion. The skin layer can also provide aesthetic appeal to the cushion including, e.g., texture, color, and combinations thereof. The skin layer can be continuous or discontinuous and can comprise of any suitable composition including, e.g., synthetic polymer, natural polymer, and combinations thereof. Exemplary materials for the skin layer can include a polyurethane material, a polyolefin material, a polyvinyl chloride material or the like.

Over time the properties of the annular cushion can change due to wear, material changes in one or both of the foam portion and the skin layer of the annular cushion, physical damage to the annular cushion which would necessitate replacement of the annular cushion on the auditory protection device. Present practice relies on time based protocols for determining when the annular cushions need to be replaced rather than on their actual condition.

The present application provides a test protocol and method 200 to aid the wearer in determining the end of service life (ESL) for the cushions on their auditory protection device as illustrated in Fig. 2. The method 200 generally comprises the steps of measuring a wear parameter 210 associated with a component of an auditory protection device, i.e. the cushions; determining an amount of wear 220 incurred by the component of an auditory protection device over a period of time based on the wear parameter; identifying an amount of use time remaining 230 for the component of the auditory protection device based on the determined amount of wear, and generating a notification or alert 240 to the user of the auditory protection device as to the use time remaining for the component of the auditory protection device.

In some aspects of the exemplary method, a computing device can be used to measure the wear parameter or run an algorithm to calculate a wear parameter from data about the component of the auditory protection device. The computing device can compare the wear parameter to the threshold value and transmit an alert if the cushion has reached the end of its service life.

The threshold value can be an absolute value provided by the manufacturer.

Alternatively, the threshold value can be assigned a value that is proportional to an initial wear parameter derived from a measurement made when the component of the auditory protection device (i.e. the annular cushion(s)) is new. The initial wear parameter can be saved or stored in a datastore on a computing device, and an algorithm applied to the initial wear parameter in order to calculate the threshold value for that component of the auditory protection device.

In another aspect, the threshold value can be determined by correlating values of the wear parameter versus the protection level of the auditory protection device (e.g. noise reduction rating (NRR) defined by the United States of America’s Environmental Protection agency,

Single Number Rating (SNR) according to International Standard ISO 4869 - Acoustics - Hearing Protectors, etc.) and selected as the value of the wear parameter when the auditory protection device no longer provides the needed level of noise protection. NRRs and SNRs are used for comparing the potential noise reduction capability of different hearing protection devices. The NRR or SNR of auditory protection devices with worn components can be measured and correlated to a wear parameter to define a threshold value. For example, and auditory protection device should have an SNR of at least 30 in order to provide a desired level of auditory protection. Thus, the threshold value for a given test method can be defined as the wear parameter for an auditory protection device having a SNR of 30.

Additionally, the correlation can be expressed as a function of the wear parameter and this function can be used to estimate the amount of wear of the component of the auditory protection device as well as the amount of remaining wear. Utilizing the date that the wear parameter was measured, and the initial date of service allows an estimated time to ESL of the component to be determined.

In some exemplary embodiments, the computing device can further run an algorithm to determine an amount of wear 220 incurred by the component of the auditory protection device over a period of time based on the wear parameter received from the portable computing device; to identify an amount of use time remaining for the component of the auditory protection device based on the determined amount of wear, and/or to generate a notification that alerts a worker as to the use time remaining for the component of the auditory protection device.

The computing device may also create a status update and transmit at least one of the status update and the alert from the computing device to a personal protection equipment tracking and management system. In some examples, auditory protection device may include a communication component that can be connected to a computing device, such that the computing device can receive wear parameter data for the auditory protection device. In some embodiments, auditory protection device may be directly connected to the computing device or it may communicate the wear parameter data via wireless communications, such as via 802.11 Wi-Fi protocols, Bluetooth protocol or the like. The computing device can be a standalone terminal or can be a cloud-based application capable of collecting and storing wear data; manipulating the wear data to yield at least one of a wear parameter for the component of the auditory protection device, an amount of wear the component of the auditory protection device has been subjected to; the amount of use time remaining to the component of the auditory protection device before the component of the auditory protection device needs to be replaced and an alert to notify the user of the auditory protection device if the amount or remaining life and a projected maintenance schedule for replacing the component of the auditory protection device.

In other examples, the wearer can input wear parameter data into a remote terminal or a portable device. The portable device may communicate the wear parameter data to the computing device or may serve as a portable computing device. Exemplary portable devices can include cell phones, laptop computer or tablets which can have underlying software and/or an analytics engine to provide ESL prediction and alerting based on measurable wear parameter data.

The computing device comprises one or more computer processors; and a memory comprising instructions that when executed by the one or more computer processors cause the one or more computer processors to receive the wear parameter data. The computing device can run analytics on the wearable parameter data to determine an amount of wear incurred by the component of the auditory protection device over a period of time based on the wear parameter data received. Based upon the amount of wear, an amount of use time remaining to the ESL of the component of the auditory protection device is identified and an alert can be generated to notify the wearer of the amount of time remaining to ESL allowing timely maintenance or replacement of the component of the auditory protection device. In some aspects of the exemplary method, the data pertaining to the ESL of the component of the auditory protection device can be received by a data hub of a personal protection equipment management system.

The computing device and/or the portable device can further include a wear sensor. The wear sensor can be used to measure a wear parameter of a component of the auditory protection device. In some embodiments, the wear sensor can be an optical sensor such as a camera or photodetector. Other exemplary wear sensors can include a pressure probe, a friction sensor, a colorimetric sensor, a chemical sensor (i.e. hyperspectral, RAMAN spectroscopy), ultrasonic sensor, and the like.

At least one of the computing device and/ or the portable device can further include a datastore to retain information about the component of the auditory protection device such as the identity of the user of the auditory protection device, manufacturing date of the device, inspection and maintenance information, threshold information (values, correspondence tables, etc.) corresponding to a given wear parameter for the component of the auditory protection device. In some embodiments, the datastore may be integral with the wear sensor, computing device or portable device while in other embodiments, the datastore may be a separate component.

The amount of wear is not limited to wearing the auditory protection device but may result from normal use of the component of an auditory protection device, age of article, exposure history to chemicals, ultraviolet light, heat, etc., maintenance/storage of article, and the like.

Wear parameters can include a measure of the softness or permanent deformation of the annular cushion 115, the shape of the annular cushion, resilience/stiffness of the polymeric skin layer 118 surrounding the foam portion 115 of the annular cushion, gloss of a surface of the polymeric skin layer, color of the polymeric skin layer, and the like. In one aspect, the wear parameter can be related to the shrinkage of a portion of the annular cushion. The shrinkage may be due to a break down in the foam portion of the annular cushion or shrinkage in the polymeric skin layer due to environmental exposure, plasticizer migration or another factor.

The wear parameter can be measured by a wear sensor and communicated to a computing device either directly or indirectly by a portable device. For example, the wear sensor can be an optical sensor such as a camera. In an exemplary method, the optical sensor can capture an image of a component of an auditory protection device such as annular cushion 115 shown in Figs. 1 A and IB from which the wear parameter may be derived. The captured image can be optionally tagged with a time stamp. For example, Fig. 3 A shows an image of a new annular cushion, while Fig. 3B is an image of worn annular cushion. Image analysis can be performed on the captured image of a used or worn cushion taken by the optical sensor by one of the portable device and or computing device.

For example, a first image can be taken of a component of an auditory protection device with the optical sensor and saved to a computing device. A shape detection image analysis algorithm can be used to extract a first shape definition from the first image. In some exemplary aspects of the method, the wear parameter may be determined from the first shape definition. The computing device can then compare the wear parameter to the threshold value and transmit an alert if the cushion has reached the end of its service life. The computing device may also create a status update and transmit at least one of the status update and the alert from the computing device to a personal protection equipment tracking and management system.

Alternatively, the extracted first shape definition is then compared to a predetermined shape definition stored in the memory of the computing device, the portable device or the data store and a difference(s) between the first shape definition and the predetermined shape definition is determined. A relative change in the shape definition between the first shape definition and the predetermined shape definition can be used to indicate if the component of the auditory protection device has reached its ESL. In an exemplary aspect, the pre-determined shape definition corresponds to component of an auditory protection device when it was new prior to use. The predetermined shape definition can be saved to the datastore for subsequent comparison to first shape definitions taken after the annular cushion has undergone a period of use.

The difference(s) between the first shape definition and the predetermined shape definition can additionally be used to determine an amount of wear incurred by the component of the auditory protection device over a period of time. In one exemplary method, difference between the first shape definition and the predetermined shape definition can be compared to a standard wear curve which provides the amount or degree of wear as well as an estimate of the amount of remaining use time until ESL of the component of the auditory protection device, based on the standard conditions used to create the standard wear curve. If the estimate of remaining use time is less than a threshold value, an alert can be triggered to notify the wearer of the impending ESL of the component of the auditory protection device.

The wear parameter, amount of wear and remaining use time can be saved into the memory of the computing device, the portable device or the data store to be used in future comparative analyses for the component of the auditory protection device and can be used to create an actual used curve for the auditory protection device.

In an alternative approach, a computer vision algorithm can be applied to the first shape definition to detect, whether a change in the shape of the annular cushion has reached a predefined maximum value. For example, a computer vision algorithm can determine the radius of curvature of a side and the top surface of the annular cushion (i.e. between a side 115a or 115b and a top surface 115c of cushion 115 as identified in Fig. IB). When this radius of curvature is larger than a threshold value, then an alert can be sent to the user notifying them that the annular cushions should be replaced. For example, the profile of the component (e.g. annular cushion) of the auditory protection device can change shape over time which could reduce the effectiveness of the seal between the auditory protection device and the wearer’s head. The skin layer of the annular cushion is made of plasticized polyvinylchloride (PVC). Over time the plasticizer can diffuse out of the skin layer and into the foam portion under the skin layer as the cushion ages. The reduction in plasticizer in the skin layer can result in shrinkage of the skin layer, leading to permanent deformation in the shape of the cushion, which in turn can be detected by an optical sensor (e.g. camera vision).

Figs. 3 A and 3B are photographs of a new cushion for an auditory protection device and one that has been subjected to a period of wear, respectively. These figures show how the shape of the annular cushion changes as the cushion ages. In particular, the aged annular cushion of Fig. 3B has a rounder shape having a higher radius of curvature than the new annular cushion.

Image analysis in combination with an edge detection algorithm can be used to determine a shape definition corresponding to the image. Further image analysis can extract a wear parameter (e.g. a radius of curvature between a side 115b and a top surface 115c of cushion 115 as identified in Fig. IB) from the shape definition. For example, the image in Fig. 3A corresponds to the shape definition shown in Fig. 4A and may be referred to as the predetermined shape definition. The threshold value can be assigned a value that is proportional to wear parameter derived from predetermined shape definition the component of the auditory protection device when the component is new.

Similarly, the image in Fig. 3B, (i.e. the first image) corresponds to the first shape definition shown in Fig. 4B. The radius of curvature wear parameter or first wear parameter can be derived from the first shape definition and compared to the threshold value. When this radius of curvature wear parameter is larger than a threshold value, an alert can be sent to the user notifying them that the annular cushions have reached their ESL and should be replaced.

In more detail, an exemplary ESL detection method can comprise taking a first, time stamped image of the article of hearing protection with the optical sensor, using a computing device or a portable device to apply an image analysis algorithm and/or a shape detection algorithm to the first time stamped image to extract a first shape definition from the first image; calculating/measuring a wear parameter (i.e. radius of curvature) from the first shape definition; comparing of the wear parameter to a threshold value; generating a notification to alert the wearer if the wear parameter exceeds the threshold value indicating that the annular cushions are at or near their ESL. The shape definition and/or wear parameter can be saved in a datastore for future use. In the event that ESL has not been reached the auditory protection device can be used until the next status check date. At the next status check, another time stamped image or second image of the annular cushion can be captured, and a second definition and a second wear parameter derived through image analysis. The second wear parameter can be directly compared to the threshold value to determine if ESL has been reached. Alternatively, the computing device can create a regression model to anticipate the ESL from the threshold value, first and second wear parameters and time stamp data. The model can be stored in the datastore of a computing device. The model can then be used to estimate the time remaining until the ESL of the annular cushions. Data from additional status checks can be incorporated into the model to refine the regression and improve the ESL prediction.

In an alternative method, a deep learning model can be trained with images of good cushions and cushions that are past its ESL and need replacing. When an image of a used cushion is analyzed by the deep learning model, the model will identify features in the image that correspond features in a “good cushion” or features in a cushion that “needs replacing” from which the deep learning model will determine if the used cushion under test has reached its ESL.

In an alternative deep learning model, the model will be trained with images that are labeled with a known wear parameter. When an image of a used cushion is analyzed by the deep learning model, the model will determine the wear parameter.

An alternative exemplary ESL detection method to determine if a used cushion has deteriorated beyond useful performance is a simple indent/response method which is illustrated schematically in Fig. 5. This method comprises pressing a probe 300 against the surface 115c of cushion 100 (indicated by the broken line) to create an indentation 320 in cushion, as shown in the solid line representation of cushion 100’. The contacting end of the probe can be pointed, curved or blunt. The probe is withdrawn and a recovery time (i.e. the wear parameter) is measured as the time that it takes surface 115c’ to be restored to its original state (i.e. surface 115c). The probe can be a standard probe or an item that the wearer of the auditory protection device will have readily available (e.g. a Sharpie_® Permanent marker or pen) which enables the wearer to conduct a quick test to check the status of their auditory protection before they begin their shift or task.

A new cushion has softer polymeric skin layer resulting in longer recovery time (i.e. the time taken for the indentation to disappear), while a used cushion has stiffer polymeric skin layer resulting in shorter recovery time. In general, the stiffer the polymeric skin layer, the shorter the recovery time. The measured recovery time/wear parameter can be compared to a threshold value and/or to a correlation curve. When the recovery time falls below a threshold recovery time, the annular cushions have reached ESL and should be replaced.

A correlation curve can be created that is a plot of the wear parameter or recovery time versus noise reduction rating and the threshold value for the recovery time can be set as the recovery time when the auditory protection device no longer provides the needed level of noise protection.

In the simplest form of the indent/response test method, a probe is depressed so that the annular cushion is indented by 2 mm, preferably by at least 3 mm, and more preferable at least 5 mm up to a maximum indentation of about 10 mm. (Note: different indention depths can be used depending on the thickness of the annular cushions.) The probe is withdrawn, and the wearer counts how many seconds it takes for the surface to rebound to its original state. If the recovery time is less than the threshold recovery time, the cushions have reached ESL and should be replaced.

Preferably, an exemplary indent/response test method can utilize an optical sensor or camera on a portable device such as a cell phone, tablet or laptop computer as an optical sensor to record the indent/response sequence. For example, the exemplary indent/response test method comprises taking a first time stamped image of the component of auditory protection device with the optical sensor; using a shape detection algorithm to extract a first shape definition from the first image; depressing a surface of component of auditory protection device taking a second, time-stamped image of the modified article of hearing protection with the optical reader; and using the optical sensor to measure a recovery time of the surface of the component of auditory protection device based on at least a second time stamped image. The shape detection algorithm is used to extract a second shape definition from the second time stamped image. Comparing the extracted first shape definition to extracted second shape definition to determine the point at which they are the same yields the recovery time or wear parameter. Specifically, the recovery time is calculated as the difference between a first time stamp of the first image and a second time stamp of the second image and wherein the recovery time is set as the wear parameter. The wear parameter is compared to a threshold value to determine if the cushion has reached an end of its service life.

In an alternative aspect, a timing device such as a stopwatch, can be used to measure the recovery time of the surface of the cushion.

In other aspects of the methods, an application on the portable device can record a video of the recovery of the surface of the cushion, analyze the recording use a video analysis module to determines the recovery time from the recorded video. The application then compares the measured recovery time to the threshold value and issues a notification of to the user if the threshold value has been met; store the test results and/or notify the wearer and/or their supervisor if the annular cushions need to be replaced.

Alternatively, an exemplary indent/response test method can utilize a simple test apparatus module including a specimen holder, a camera, light source, and indentation means. The annular cushion can be placed in the specimen holder. The indent-rebound test sequence is initiated. The test apparatus then activates the probe and camera to video capture the test sequence, video, conducts video analysis to determine the measured recovery time; compares the measured recovery time to determine if the ESL condition has been meat and send a notification to the wearer if cushion replacement is needed. The test apparatus could additionally store and track the measurement history related to a particular auditory protection device.

A preferable indent/response test method comprises taking a first, time stamped image of the article of hearing protection with the optical sensor, using a computing device or a portable device to apply an image analysis algorithm and/or a shape detection algorithm to the first time stamped image to extract a first shape definition from the first image; calculating/measuring a wear parameter (i.e. radius of curvature) from the first shape definition; comparing of the wear parameter to a threshold value; generating a notification to alert the wearer if the wear parameter is exceeds the threshold value indicating that the annular cushions are at or near their ESL.

Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment.

Depending on the embodiment, certain acts, events, or steps of any of the methods described herein can be performed in a different sequence, can be added, merged, or left out altogether (e.g., not all described steps or events are necessary for the practice of the method). Moreover, in certain embodiments, steps, acts or events can be performed concurrently, e.g., through multi -threaded processing, interrupt processing, or multiple processors or processor cores or on other parallel architectures, rather than sequentially.

Computing devices, systems and modules described herein may comprise software, firmware, hardware, or any combination(s) of software, firmware, or hardware suitable for the purposes described herein. Software and other modules may reside on servers, workstations, personal computers, computerized tablets, PDAs, and other devices suitable for the purposes described herein. Software and other modules may be accessible via local memory, via a network, via a browser, or via other means suitable for the purposes described herein. Data structures described herein may comprise computer files, variables, programming arrays, programming structures, or any electronic information storage schemes or methods, or any combinations thereof, suitable for the purposes described herein. User interface elements described herein may comprise elements from graphical user interfaces, command line interfaces, and other suitable interfaces.

Further, the processing of the various components of the described methods can be distributed across multiple machines, networks, and other computing resources. In addition, two or more components of a system can be combined into fewer components. Various components of the illustrated systems can be implemented in one or more virtual machines, rather than in dedicated computer hardware systems. Likewise, the data stores or repositories can represent physical and/or logical data storage, including, for example, storage area networks or other distributed storage systems.

The method is described with respect to the flow chart of Fig. 2. Each block of the flow chart may be implemented in part or in total by computer program instructions. Such instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the acts specified in the flow chart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the acts specified in the flow chart and/or block diagram block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the acts specified in the flow chart and/or block diagram block or blocks. While specific methods of determining ESL for components of an auditory protection device are provided herein, these embodiments have been presented by way of example only and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the described methods and systems may be made without departing from the spirit of the disclosure. Various modifications of the methods of determining ESL for a component of an auditory protection device including equivalent protocols to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the present specification. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.

EXAMPLES

Test Methods Determining SNR. A plurality of annular cushions for an auditory protection were evaluated using the

Acustic Test Fixture (ATF) measuring system according to ISO 4669-3. The data were used to extract the SNR number for each sample as shown in Table 1.

Indent/Response Test Method

An annular cushion was removed from a cup of an auditory protection device and placed on a solid surface. A probe was pressed into the surface of the annular cushion to a depth of approximately 7 mm. An end of a cap of a Sharpie Fine Point Permanent Marker was used as the probe. The probe was withdrawn, and the recovery of the cushion was monitored via a video recording using the camera on an iPhone 7 cellular phone. The recovery time was determined as the elapsed time required for the surface of the annular cushion to return to its original state. An average of at least measured response times for each sample is provided in Table 1.

Samples

Samples were obtained from the field (used by workers) which showed at varying stages of decay (use time). The higher sample number reflects greater “age” of the cushion. Table 1.

As mentioned previously, an SNR below 30 does not provide adequate noise protection. Therefore, the Indent/Response Test Method indicates that the ESL of the annular cushions is reached when the response time is less than about 3 seconds. Thus, the Indent/Response Test Method can be used as a quick field test to determine if the annular cushions should be replaced.

Claims

What is claimed is:

1. A method of determining an end in service life for a component of an auditory protection device, comprising: determining a wear parameter related to a degradation in a physical characteristic of a cushion of the auditory protection device; comparing the wear parameter to a threshold value; and making a determination based on the threshold value (certain rules) if the cushion has reached an end of its service life.

2. The method of claim 1, wherein component of the auditory protection device is a cushion comprising a foam portion covered by a polymeric skin layer.

3. The method of claim 2, wherein the physical characteristic is one of shape of the cushion, resilience of the cushion of polymeric skin layer, gloss of a surface of the polymeric skin layer, stiffness of the polymeric skin layer and color of the polymeric skin layer.

4. The method of claim 1, wherein the wear parameter relates to the shrinkage of a portion of the cushion.

5. The method of claim 1, wherein the threshold value is proportional to an initial wear parameter derived from a measurement made when the cushion is new.

6. The method of claim 1, further comprising storing an initial wear parameter derived from a measurement made when the cushion is new in a datastore on a computing device and applying an algorithm to the initial wear parameter to calculate the threshold value.

7. The method of claim 6, further comprising entering the wear parameter into the computing device, wherein the computing device compares the wear parameter to the threshold value and transmits an alert if the cushion has reached the end of its service life.

8. The method of claim 7, further comprising creating a status update and transmitting at least one of the status update and the alert from the computing device to a personal protection equipment tracking and management system.

9. The method of claim 1, further comprising receiving information from a wear sensor attached to a computing device.

10. The method of claim 9, wherein the wear sensor is one of an optical sensor, a friction sensors, colorimetric sensor, chemical sensor and a pressure sensor.

11. The method of claim 10, wherein the wear sensor is an optical sensor.

12. The method of claim 11, further comprising: using the optical sensor to determine the wear parameter associated with component of auditory protection device.

13. The method of claim 12, further comprising:

(a) taking a first image of the component of auditory protection device with the optical sensor;

(b) using a shape detection algorithm to extract a first shape definition from the first image; and

(c) extracting the wear parameter from the first shape definition.

14. The method of claim 13, comparing the wear parameter to a threshold value, wherein the wear parameter is a radius of curvature determined from the first shape definition and wherein the threshold value is proportional to an initial wear parameter derived from an original shape definition for a new component of hearing protection device.

15. The method of any of the previous claims, further comprising comparing the wear parameter to a correlation curve for the wear parameter versus service life to determine an estimate of use time remaining for the component of auditory protection device.

16. The method of claim 12 further comprising: taking a first time stamped image of the component of auditory protection device with the optical sensor; using a shape detection algorithm to extract a first shape definition from the first image; depressing a surface of component of auditory protection device taking a second, time- stamped image of the modified article of hearing protection with the optical reader; using the optical sensor to measure a recovery time of the surface of the component of auditory protection device based on at least a second time stamped image by using a shape detection algorithm to extract a second shape definition from the second time stamped image and comparing the extracted first shape definition to extracted second shape definition to determine the point at which they are the same.

17. The method of claim 16 further comprising calculating the recovery time as the difference between a first time stamp of the first image and a second time stamp of the second image, wherein the recovery time is the wear parameter.

18. The method of claim 1, further comprising depressing a surface of the cushion with a probe, removing the probe and measuring a recovery time for the surface to return to its original state, wherein the recovery time is the wear parameter that is compared to the threshold value.

19. The method of claim 10, wherein the threshold value is set to be 50% of the wear parameter derived from a measurement made when the cushion is new and wherein the end of the cushion’s service life is determined when the wear parameter is less than the threshold value.

20. The method of claim 1, further comprising determining the threshold value by measuring the wear parameter of the cushion prior to use.