Verifying the attenuation of earplugs in situ: Method validation using artificial head and numerical simulations

Bockstael, Annelies; Greve, Bram de; Renterghem, Timothy Van; Botteldooren, Dick; D’haenens, Wendy; Keppler, Hannah; Maes, Leen; Philips, Birgit; Swinnen, Freya; Vinck, Bart

doi:10.1121/1.2945709

Cited by 8 publications

(14 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One important remark is that the presence of the flexible silicone tube will not alter sound propagation in the outer ear canal an sich [12] butitdoes affect the attenuation of the earplug. This seems not critical since previous analyses have pointed out that changing the earplug'sattenuation does not influence the transfer functions [10].…”

Section: Measurements Of the Transfer Functionmentioning

confidence: 99%

“…Since the captured transfer functions should be absolutely independent of the test signal, the test space and the microphones, tworeference free-field microphones are incorporated. All calibration steps are described in detail in previous work [10].…”

Section: Measurements Of the Transfer Functionmentioning

confidence: 99%

“…Therefore the sound pressure is simultaneously registered at the MIRE measurement microphone and at the eardrum for both aH ead And Torso Simulator (HAT S) and nineteen human subjects, all equipped with custom-made acrylic earplugs (see Figure 1).M easurements takep lace in an anechoic room to prevent disturbances from background noise or reverberation; all details can be found in [10] and [11].…”

Section: Measurements Of the Transfer Functionmentioning

confidence: 99%

“…Akey factor of this approach is that both pressure p and particle velocity u are discretised in Cartesian grids; more details can be found in [10]. This technique is chosen since the time domain method is both efficient and accurate and relies on as imple and straightforward concept.…”

Section: Simulations Of the Transfer Functionsmentioning

confidence: 99%

“…Moreover, the measured transfer functions can be predicted with aF inite-Difference Time-Domain (FDTD)m odel of an ear canal occluded by an earplug [10]. Further investigation has revealed that the FDTD Figure 1.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Digital Filters for Accurately Verifying the Performance of Hearing Protectors in Use

Bockstael¹,

Deschrijver²,

Botteldooren³

et al. 2010

Acta Acustica united with Acustica

Self Cite

View full text Add to dashboard Cite

SummaryThe performance of hearing protectors can be assessed in situ by measuring the sound pressure inside the ear canal following the Microphone In Real Ear (MIRE)p rotocol. Thus acustom-made earplug has been designed with an inner bore, allowing the insertion of the MIRE measurement microphone. However, the actual exposure levelcan only be accurately predicted if the relationship, henceforth called transfer function, between the sound levelatthe microphone and at the eardrum is known. Previous research has revealed that the transfer function can be precisely approximated with an individualized FDTD model, butasimplified method is needed for practical implementation due to the time-consuming nature of this numerical technique. In this matter,aone-dimensional analytical model appears inadequate, hence an approximation to the detailed FDTD model based on digital filter design is proposed instead. Twod i ff erent approaches have been applied to estimate the individualized filter coefficients: multiple linear regression and Multivariate Orthonormal Ve ctor Fitting (MOVF).I ng eneral, both methods can predict an individual'st ransfer function quite accurately if the length of the earplug'si nner bore and the length of the residual part of the ear canal behind the protector are known. However, MOVF seems more reliable for ears with alonger residual part.

show abstract

Section: Measurements Of the Transfer Functionmentioning

confidence: 99%

Section: Measurements Of the Transfer Functionmentioning

confidence: 99%

Section: Measurements Of the Transfer Functionmentioning

confidence: 99%

Section: Simulations Of the Transfer Functionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Digital Filters for Accurately Verifying the Performance of Hearing Protectors in Use

Bockstael¹,

Deschrijver²,

Botteldooren³

et al. 2010

Acta Acustica united with Acustica

Self Cite

View full text Add to dashboard Cite

show abstract

Real-world attenuation of custom-moulded earplugs: Results from industrial in situ F-MIRE measurements

Kusy¹,

Châtillon²

2012

Applied Acoustics

View full text Add to dashboard Cite

Abstract:The attenuation provided by hearing protection devices (HPDs) is traditionally determined under laboratory conditions by means of a standardised method titled REAT (Real Ear Attenuation at Threshold). This performance is often overestimated compared to what has been measured so far in industrial reality. Concerning the earmuff, the formable earplug and preformed earplug type of HPD, there are numerous data related to the discrepancy between, on one hand, the laboratory measured attenuation which is labelled by the manufacturers and, on the other hand, the in situ estimated attenuation. But, few exist concerning custom-moulded earplug (CMEP) type protection devices. This paper presents the practical application of measurements intended to estimate the attenuation of this type of protection device while it is being worn by users during execution of their task. Three manufacturers of hearing protectors took part in this initiative; this participation involved the manufacturing of custom-moulded earplugs with a miniature microphone inserted. The measurements were carried out on 63 employees in nine industrial sites with diverse activities. The estimate of this in situ attenuation, in this study called level reduction (LR), was obtained from the difference between the noise exposure level measured close to the ear of the employee and the residual noise level measured under the earplug. The CMEP level reduction estimated in situ highlighted significant variability characteristics. The results of the measurements confirm the overestimation of the values indicated by the manufacturers. From 3 to 5 dB at high frequencies, the discrepancy can reach 8-10 dB at medium and low frequencies. The study also confirms that CMEPs which have been tested here, like other earplugs types, are unsuited to attenuate low frequencies.

show abstract

Development, validation and application of a generator for distortion product otoacoustic emissions

et al. 2016

Self Cite

View full text Add to dashboard Cite

The application area of distortion product otoacoustic emissions (DPOAEs) is expanding beyond clinical routines, towards new measurement environments, protocols, wearable hardware and more robust algorithms. To enable systematic assessment of the performance of commercial and prototype OAE equipment under various measurement conditions without a need for recruitment of the test subjects, a DPOAE generator that produces a reliable and stable response is proposed. This article suggests simple design for such generator that is easy to reproduce by third parties. This design uses an approximate model for middle and inner ear dynamics focusing on typical operational conditions. The DPOAE generator is embedded in a head and torso simulator enabling testing for various probe fitting and also residual ear canal volume effects. Measurement of the DPOAE generator response with clinical equipment shows that the response obtained falls within the range of human normative data. It is also shown that the generator is applicable out- * Corresponding author Email address: madnadje@intec.ugent.be (Mirjana Adnadjevic) November 26, 2016 side the clinical routines and is able to highlight differences in measurements obtained with different clinical OAE measurement devices. Preprint submitted to Applied Acoustics

show abstract

Verifying the attenuation of earplugs in situ: Method validation using artificial head and numerical simulations

Cited by 8 publications

References 25 publications

Digital Filters for Accurately Verifying the Performance of Hearing Protectors in Use

Digital Filters for Accurately Verifying the Performance of Hearing Protectors in Use

Real-world attenuation of custom-moulded earplugs: Results from industrial in situ F-MIRE measurements

Development, validation and application of a generator for distortion product otoacoustic emissions

Contact Info

Product

Resources

About