Thesis (Ph.D.)--Kent State University, 2007. / Title from PDF t.p. (viewed Mar. 31, 2008). Advisor: Linda B. Walker. Keywords: music, hearing, band directors, teachers, audiology, spl, musicians. Includes survery instrument. Includes bibliographical references (p. 171-182).

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 87-96).

Federal law requires hearing protection device (HPD) manufacturers to provide attenuation ratings for use in estimating workers’ protection levels. These ratings, which are laboratory obtained, typically overestimate the actual protection levels achieved in the workplace. This research investigated laboratory protocols for yielding improved estimates of HPD in-field performance. Two experiments were conducted. The first was a pilot study developed by an American National Standards Institute (ANSI) working group. In this experiment, two types of earplugs were tested, a user-molded, malleable foam plug and a pre-molded, multi-sized rubber plug. Attenuation data (obtained using a psychoacoustical real-ear-attenuation-at-threshold measurement procedure) were collected across 10 subjects who entered the study as novice HPD users but were considered experienced HPD users in the latter half of the study. Four testing protocols involving two levels of HPDs, two levels of instruction-insertion techniques, and two levels of user experience were investigated. The same 10 subjects participated in all treatment conditions of the experiment. The second experiment involved similar protocols as the first; however, only one plug type was tested (the pre-molded, multi-sized rubber plug). Four testing protocols involving two levels of instruction-insertion techniques, two levels of user experience, and two levels of auditory feedback [fitting noise] were investigated. Forty subjects participated; each subject was tested in two treatment conditions. The attenuation results of each experiment were analyzed by statistical techniques. Statistical comparisons of results were made between the two experiments as well as between the experiments and selected field data. The major finding of the research was that fitting noise did not help subjects achieve higher attenuation [better protection] when consciously used for that purpose. Other findings indicated that novice subjects using only HPD manufacturer's instructions achieved attenuation that more closely represented the field attenuation than subjects tested under other conditions. However, the results were plug specific, in that no laboratory protocols yielded attenuation similar to the field data for the foam plug. / Master of Science

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. / Master of Science

Call number: LD2668 .T4 1986 W23 / Master of Arts / Communication Studies

The acoustic reflex refers to the contraction of a middle ear muscle in response to sound. The contraction causes a stiffening of the middle ear system and, consequently, the flow of acoustic energy to the cochlea is impeded. By measuring the change in admittance in the auditory system during sound stimulation it is possible to indirectly monitor the middle ear muscle contractions. Such measurements provide useful information regarding the integrity of the auditory system and the location of the auditory pathology.

Speech reception threshold testing by bone conduction is very useful in diagnostic audiometry. However, there are little data regarding the CID W-1 spondee word lists used with the Radioear B-71 and B-72 and Pracitronic KH 70 bone conduction vibrators at higher presentation levels for testing hearing impaired clients. Data are needed in order that results of speech reception thresholds using the CID W-1 word lists via these three bone conduction vibrators at higher intensity levels can be used confidently in the clinic. More data are available for speech reception thresholds using the CID W-1 word lists via earphones. This study compared speech intelligibility presented via bone conduction at higher intensity levels to that presented via earphone at higher intensity levels. Twelve normal hearing adults, with thresholds artificially elevated by binaural speech noise masking to simulate a hearing impairment, were used as subjects. Recorded CID W-1 spondee word lists were presented via four transducers: Radioear B-71, Radioear B-72, and Pracitronic KR 70 bone vibrators, and a TDH-39 earphone. Investigation of each bone conduction vibrator was accomplished by using forehead placement and using binaural speech noise masking via earphones. Investigation of the earphone was accomplished by simultaneously presenting binaural speech stimuli and speech noise masking. Spondees from the CID W-1 word lists were presented to the subject via a transducer. A bracketing technique was used to estimate the speech reception threshold. Using the intensity level of the predetermined SRT as 0 dB, each list was presented at one of the following levels: +4, +2, O, -2, -4, and -6. Performance-intensity functions, the percentage of correctly identified spondees as a function of presentation level, were obtained for each transducer. The percentage of spondees correctly identified increased with the stimulus level for all transducers. Using linear regression, the line of best fit was calculated for each subject's data under each transducer condition. A one way analysis of variance indicated that there was a significant difference in the slopes of the performance-intensity functions of the transducers. A follow-up test for the one way analysis of variance indicated that there was a signficant difference between the TDH-39 earphone and each of the bone conduction vibrators. There were no significant differences among the bone conduction vibrators. Results of the study suggested that CID W-1 word lists and the 50 percent criterion may be inappropriate for use with these bone conduction vibrators at higher intensity levels. Given that there was a preponderance of data points below 50 percent for the bone vibrators, a criterion of less than 50 percent might be more appropriate. Because presentation levels might be elevated for sensorineural hearing impaired listeners, their SRT performances could be affected. Consequently, the results of speech reception threshold testing via bone conduction at higher intensity levels should be interpreted with caution in clinics.

Thesis (M.S.)--Brigham Young University. Dept. of Audiology and Speech-Language Pathology, 2005. / Includes bibliographical references (p. 49-52).

The purpose of this study was to establish a normal, bone conducted intensity level for the speech reception threshold (SRT) and obtain a normal performance intensity function by bone conduction from 0 dB SL (threshold) through the maximum output level of the standard audiometer. All bone conducted speech test materials consisted of pre-recorded W-2 spondiac words and NU-6 monosyllabic speech discrimination word lists.

The question of whether or not an individual suffering from a hearing loss is capable of hearing an auditory alarm or warning is an extremely important industrial safety issue. International standard ISO 773 1—1986(E), Danger Signals for Work Places — Auditory Danger Signals, requires that any auditory alarm or warning be audible to all individuals in the workplace, including those suffering from a hearing loss and/or wearing hearing protection devices (HPDs). Very little research has been conducted to determine how an individual's hearing level affects his/her ability to detect an auditory alarm or warning in a high-noise environment while wearing an HPD. The research effort described herein was undertaken to determine how the ability to detect an alarm or warning signal changed for individuals with normal hearing and two levels of hearing loss as the levels of masking noise and alarm were manipulated. Pink noise was used as the masker since it is a generally-accepted, generic substitute for industrial noise. A heavy-equipment reverse alarm was used as the signal since it is a common alarm in industrial facilities and construction sites. The rating method paradigm of signal detection theory was used as the experimental procedure in order to separate the subjects’ absolute sensitivities to the alarm from their individual criteria for deciding to respond in an affirmative manner. Results indicated that even at a fairly low signal-to-noise ratio (0 dB), individuals with a substantial hearing loss [a pure-tone average (PTA) hearing level on the order of 45-50 dBHL in both ears] are capable of hearing the alarm while wearing a high-attenuation earmuff. Predictive models were developed using nonlinear regression techniques. These models may be used to predict whether or not individuals with known hearing levels will be capable of hearing the alarm under known conditions or to determine the level of alarm presentation in order to be heard reliably by individuals with a specified range of hearing for given noise levels / Ph. D.