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Browsing by Author "Mauney, Daniel W."

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    Custom-fitting earplug formed in situ using foaming action
    (United States Patent and Trademark Office, 1992-07-21)
    A custom-fitting earplug (18) for hearing protection or other ear applications, or in-ear communications device mounting (40) is fabricated in situ by depositing a foaming material (14 or 24) within the person's ear (10 or 42, respectively) and allowing the foaming material (14 or 24) to expand therein to form foam (16 or 44, respectively). By applying slight pressure from outside the person's ear (10 or 42) through the stem (13) and/or keeper (11) during expansion, the foam (16 or 44, respectively) will be tightly packed in and conform to the ear canal. An optional sheath (15 or 36) positioned over the foaming material (14 or 24, respectively) serves to provide a smooth outer surface for the earplug (18) or communications device (40) produced and can aid in defining and limiting the expansion of the foam (14 or 24, respectively).
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    Investigation of physical and psychophysical methods for the attenuation measurement of circumaural hearing protectors with implication for field use
    Mauney, Daniel W. (Virginia Tech, 1994)
    A field-implementable measure is needed to estimate the attenuation workers are achieving with their hearing protectors in the field. Alternative measures for assessing a hearing protector's effectiveness were evaluated through comparison to the standardized real-ear attenuation at threshold (REAT) method, termed 1I3-REAT, a psychophysical procedure (ANSI S3.19-1984). One alternative deviated from the standardized procedure primarily through utilizing a pure-tone audiometer coupled to an amplifier and loudspeaker for the sound field presentation of pure tones (Pr -REAT). The other alternative. tenned microphone in real-ear (MIRE), used miniature microphones in each concha and just outside of each of the subject's two ears to physically measure the attenuation of the protector using both insertion loss (lL-MIRE) and noise reduction (NR-MIRE) procedures. Comparisons between the alternative measures were made across nine 113 octave bands centered at 125, 250, 500, 1000, 2000, 3150,4000, 6300, and 8000 Hz. The experiment also explored a means for predicting broadband attenuation from data of a single 113 octave band through a regression analysis for both PT -REAT tests and NR-MIRE tests. Results showed that when comparing the PT -REAT test and the standardized 1/3-REA T method, the standardized method exhibited significantly greater attenuation at most of the 1/3 octave bands tested. The difference, however, may be due to the higher ambient noise levels present in the pure tone condition. The MIRE measures also showed some significant differences with the standardized 1/3-REAT method for the values collapsed across protectors, with the direction of the difference changing with test band. At 125 Hz, the MIRE metrics yielded significantly lower attenuation, while from 500 to 6300 Hz, the 1/3-REAT method generally yielded significantly lower attenuation. These differences may be due in part to the occlusion effect and the bone conduction of sound. In general, however, the size and consistency of the differences across hearing protection devices (HPDs) suggest that PT-REAT and MIRE measures hold promise for providing quick and relatively accurate estimations of an HPD's attenuation in the field. Results of the regression analyses indicated that single test band data obtained at 250 and 500 Hz, from both PT-REAT and NR-MIRE metrics, provided the best predictions for the hearing protectors tested in this study, based on their Pearson product-moment correlation coefficients.
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    Psychophysical investigation of the real-ear attenuation of hearing protection devices under different sound-field diffusivity conditions
    Mauney, Daniel W. (Virginia Tech, 1991)
    Certain U. S. and international consensus standards governing hearing protection device (HPD) attenuation testing specify the use of a diffuse sound field to ensure the sound field remains uniform and random-incidence in an envelope about the subject’s head (ANSI, 1974; ANSI, 1984; British BSI 5108:1983; Canadian CSA Z94.2-M1984; ISO 4869- 1:1990; Swedish SS 882151). However, there are very few experimental data to support these restrictive requirements. The research presented herein investigated this issue by applying three different environments in tests of the attenuation of four different hearing protectors (three earmuffs and one earplug) at each of nine 1/3 octave band frequencies centered at 125, 250, 500, 1000, 2000, 3150, 4000, 6300, and 8000 Hz. One testing environment comprised a reverberant room with three loudspeakers, one firing in each room plane, that met all the specifications for testing under ANSI S3.19-1974 (ANSI, 1974). The other two environments progressively degraded the diffusivity of the sound field through the use of a single loudspeaker and room surface treatment with absorptive panels. A psychophysical real-ear-attenuation-at-threshold procedure was used to obtain attenuation data. The results showed small, but statistically significant, differences in attenuation among the three environments for specific test frequencies. Due to their statistical significance, these differences preclude direct comparison of attenuation data obtained in these different environments, especially when the data are used for purposes such as technical design research, product comparison and/or labeling, and testing standards development. However, being of small magnitude, these differences are not great enough to prevent obtaining an estimation of the attenuation that an individual is achieving with a particular device under these alternative environments. With this in mind, the use of an industrial audiometric test booth may be beneficial for determining an individual worker’s protection levels actually achieved on the job. In sum, the interpretation of the results differs depending upon the intended purpose of the testing.