The Impact of Earplugs and Eye Masks on Sleep Quality in Surgical ICU Patients at Risk for Frequent Awakenings.

OBJECTIVES: Sleep disturbances may contribute to the development of delirium, prolonged ICU stay, and increased mortality. There is conflicting data on the effectiveness of earplugs and eye masks for sleep promotion in the ICU. This study evaluates the impact of earplugs and eye masks on sleep quality in postoperative surgical ICU patients at risk for frequent awakenings. DESIGN: Prospective randomized controlled trial. SETTING: Surgical ICU within the University of Texas Southwestern Medical Center. PATIENTS: Adult, female patients admitted to the surgical ICU requiring hourly postoperative assessments following breast free flap surgery between February 2018 and October 2019. INTERVENTIONS: Patients were randomized into an intervention group or a control group. The intervention group received earplugs and eye masks in addition to standard postoperative care, whereas the control group received standard postoperative care. MEASUREMENTS AND MAIN RESULTS: The primary outcome was overall sleep quality assessed via the Richards-Campbell Sleep Questionnaire. Secondary outcomes of patient satisfaction and rates of ICU delirium were assessed with a modified version of the Family Satisfaction in the ICU survey and the Confusion Assessment Method for the ICU. After a planned interim analysis, the study was stopped early because prespecified criteria for significance were attained. Compared with the control group's average Richards-Campbell Sleep Questionnaire total score of 47.3 (95% CI, 40.8-53.8), the intervention group's average Richards-Campbell Sleep Questionnaire total score was significantly higher at 64.5 (95% CI, 58.3-70.7; p = 0.0007). There were no significant between-group differences for Confusion Assessment Method for the ICU scores or modified Family Satisfaction in the ICU survey scores. CONCLUSIONS: These results suggest that earplugs and eye masks are effective in improving sleep quality in ICU patients undergoing frequent assessments. The results strengthen the evidence for nonpharmacologic sleep-promoting adjuncts in the ICU.

Hearing protective devices and its role in Noise induced hearing loss: An interventional study.

This Quasi experimental study was conducted with the objective to determine the effectiveness of preventive measures including awareness programme and use of hearing protective devices (HPDs) for the prevention and control of Noise Induced Hearing Loss among Oil and Gas field workers from January 2015 to March 2016. A total of 120 workers were selected by convenient sampling, and subjected to pure tone audiometry (PTA) to obtain hearing thresholds followed by intervention with HPDs and retesting a year later. The Mean pure tone thresholds on first visit was 21.19±11.60 dB in right and 24.66±13.26 dB in left ear, while means at second visit (after one year) were 20.65±10.44 dB and 21.45±11.74 dB for the right and left ears respectively with statistically significant difference (p=0.001) for the left ear on t-test. However the difference of frequency and percentage of the participants with normal and reduced hearing at both visits was significant (chi square P=0.001). Hearing protective devices (HPDs) are an effective means to prevent NIHL in workers of oil and gas fields.

Design of nonlinear active noise control earmuffs for excessively high noise level.

When exposed to high levels of noise, earmuffs are often used to avoid hearing loss. However, active noise control earmuffs may exhibit nonlinearities under excessive levels of noise, due to their low-power characteristics of the loudspeakers, and thus nonlinear control algorithms are required to improve the control performance. In this paper, an analytical model of a nonlinear active noise control earmuff is investigated. Based on this model, a robust state feedback control law is designed in the framework of linear matrix inequalities with respect to the parametric uncertainties of the loudspeaker and the limitation of control input. Then the backstepping approach is adopted to force the nonlinear part of the loudspeaker to track the derived state feedback signal and estimate the unknown parameters. Both recorded vehicle noise and multi-frequency noise are used to test the effectiveness of the proposed controller and the control performance is compared with that of a widely accepted nonlinear generalized functional link artificial neural network algorithm. Simulation results demonstrate that the proposed controller is capable of attenuating the interior noise and reducing harmonic and intermodulation distortions significantly.

Caring for musicians' ears: insights from audiologists and manufacturers reveal need for evidence-based guidelines.

OBJECTIVE: This study investigated clinical care delivered to musicians in Australia by audiologists and manufacturers of musicians' hearing protectors (MHP). DESIGN: Audiologists with experience treating musicians were invited to complete a survey on their service delivery. A second survey was administered to manufacturers of MHPs. STUDY SAMPLE: Four manufacturers of MHP and 31 audiologists completed the surveys. Post hoc analyses were performed comparing the responses of audiologists with more versus less clinical experience; and those with and without musical training. RESULTS: There was considerable variation in the audiological care provided to musicians. Only one-third of audiologists performed pure-tone audiometry prior to MHP fitting, and there was little consistency across the sample in relation to impression taking, preferred attenuation or selection of canal length. There was also significant variation in the manufacturers' approach to MHP, each of whom provided different recommendations regarding preferred impression techniques and material viscosity. CONCLUSIONS: The results of this study reveal lack of consistency across the hearing healthcare sector with respect to care of musicians' hearing, with potential to impact upon the satisfaction with, and usage of, MHP. There is need for evidence-based, best practice guidelines and training to support clinical audiologists in providing optimal care.

Evaluating the effect of training along with fit testing on earmuff users in a Chinese textile factory.

A hearing protection fit testing was conducted on workers (n = 189) in a textile factory in southern China. The 3M E-A-Rfit Dual-Ear Validation System was used to measure the personal attenuation rating (PAR) on an over-the-head style earmuff at the work site. In addition, PARs were obtained several times throughout the same work shift to capture different fits on 39 workers. Follow-up visits were conducted in approximate 6-month or 12-month intervals to repeat the fit testing. Both the immediate and residual effects of training on the field attenuation of hearing protection devices obtained by workers, and the effects of training toward improving the attenuation and protection of earmuffs after a period of daily use, were observed. A questionnaire survey was used to assess the awareness of hearing health and motivation toward the use of earmuffs in a high temperature environment. The results showed that there were wide variations in PARs among the workers tested. The one-on-one training together with fit testing improved PAR and helped to reduce the negative impact caused by use of protective hair covers. Since earmuffs are often used for long periods of time (>1 year), repeating fit tests could be helpful in order to verify the attenuation received throughout their useful life.

Impact of earplugs and eye mask on sleep in critically ill patients: a prospective randomized study.

BACKGROUND: Poor sleep is common in intensive care unit (ICU) patients, where environmental factors contribute to reduce and fragment sleep. The objective of this study was to evaluate the impact of earplugs and eye mask on sleep architecture in ICU patients. METHODS: A single-center randomized controlled trial of 64 ICU patients was conducted from July 2012 to December 2013. Patients were randomly assigned to sleep with or without earplugs and an eye mask from inclusion until ICU discharge. Polysomnography was performed on the first day and night following inclusion. The primary outcome was the proportion of stage N3 sleep over total sleep time. Secondary outcomes were other descriptors of sleep and major outcome variables. RESULTS: In the intervention group, nine (30%) patients did not wear earplugs all night long. The proportion of N3 sleep was 21 [7-28]% in the intervention group and 11 [3-23]% in the control group (p = 0.09). The duration of N3 sleep was higher among the patients in the intervention group who wore earplugs all night long than in the control group (74 [32-106] vs. 31 [7-76] minutes, p = 0.039). The number of prolonged awakenings was smaller in the intervention group (21 [19-26] vs. 31 [21-47] in the control group, p = 0.02). No significant difference was observed between the two groups in terms of clinical outcome variables. CONCLUSIONS: Earplugs and eye mask reduce long awakenings and increase N3 duration when they are well tolerated. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02292134 . Registered on 21 Nov 2013.

Using Auditory Steady-State Responses for Measuring Hearing Protector Attenuation.

INTRODUCTION: Present methods of measuring the attenuation of hearing protection devices (HPDs) have limitations. Objective measurements such as field microphone in real-ear do not assess bone-conducted sound. Psychophysical measurements such as real-ear attenuation at threshold (REAT) are biased due to the low frequency masking effects from test subjects' physiological noise and the variability of measurements based on subjective responses. An auditory steady-state responses (ASSRs) procedure is explored as a technique which might overcome these limitations. SUBJECTS AND METHODS: Pure tone stimuli (500 and 1000 Hz), amplitude modulated at 40 Hz, are presented to 10 normal-hearing adults through headphones at three levels in 10 dB steps. Two conditions were assessed: unoccluded ear canal and occluded ear canal. ASSR amplitude data as a function of the stimulation level are linearized using least-square regressions. The "physiological attenuation" is then calculated as the average difference between the two measurements. The technical feasibility of measuring earplug attenuation is demonstrated for the group average attenuation across subjects. RESULTS: No significant statistical difference is found between the average REAT attenuation and the average ASSR-based attenuation. CONCLUSION: Feasibility is not yet demonstrated for individual subjects since differences between the estimates occurred for some subjects.

Using auditory steady-state responses for measuring hearing protector occlusion effect.

INTRODUCTION: The currently available methods for measuring the occlusion effect (OE) of hearing protection devices (HPDs) have limitations. Objective microphonic measurements do not assess bone-conducted sounds directly transmitted to the cochlea. Psychophysical measurements at threshold are biased due to the low-frequency masking effects from test participants' physiological noise and the variability of measurements based on subjective responses. An auditory steady-state responses (ASSRs) procedure is used as a technique that might overcome these limitations. PARTICIPANTS AND METHODS: Pure-tone stimuli (250 and 500 Hz), with amplitude modulated at 40 Hz, were presented to twelve adults with normal hearing through a bone vibrator at three levels in 10-dB steps. The following two conditions were assessed: the unoccluded ear canal and occluded ear canal. ASSR amplitude data as a function of the stimulation level were linearized using least-square regressions. The ASSR-based "physiological" OE was then calculated as the average difference between the two measurements. RESULTS: A significant statistical difference was found between the average threshold-based psychophysical OE and the average ASSR-based OE. CONCLUSION: This study successfully ascertained that it is possible to objectively measure the OE of HPD using ASSRs collected on the same participant both with and without protectors.

Selecting Hearing Protectors--It's the Fit That Counts.

In addition to selecting HPDs and documenting the PAR achieved by each worker, hearing protector fit testing is a critical component to worker training.

Noise Exposure on a Warship during Firing of a Heavy Machine Gun.

Sound pressure levels were measured on a military ship during firing of a Heavy Machine Gun (HMG). Measurements were made at three locations on the ship's bridge (the wheelhouse) and one location on the starboard bridge wing. The highest peak sound pressure levels measured on the bridge wing and on the bridge were 160.7 dB(C) (2170 Pa) and 122.7 dB(C) (27.3 Pa), respectively. The highest sound exposure levels measured on the bridge wing and on the bridge corresponding to one round being fired were 127.8 dB(A) and 88.9 dB(A), respectively. The ship's structure provided about 40 dB attenuation in the transmitted noise. The operator of the weapon would be required to wear some form of hearing protection. Based on the measured peak noise levels, there would be no requirement for bridge crew to wear any hearing protection during firing of a HMG. However, crew exposure to noise on the bridge is likely to exceed the upper exposure action value corresponding to 85 dB(A) after about 11 750 rounds.

Measurement of impulse peak insertion loss from two acoustic test fixtures and four hearing protector conditions with an acoustic shock tube.

Impulse peak insertion loss (IPIL) was studied with two acoustic test fixtures and four hearing protector conditions at the E-A-RCAL Laboratory. IPIL is the difference between the maximum estimated pressure for the open-ear condition and the maximum pressure measured when a hearing protector is placed on an acoustic test fixture (ATF). Two models of an ATF manufactured by the French-German Research Institute of Saint-Louis (ISL) were evaluated with high-level acoustic impulses created by an acoustic shock tube at levels of 134 decibels (dB), 150 dB, and 168 dB. The fixtures were identical except that the E-A-RCAL ISL fixture had ear canals that were 3 mm longer than the National Institute for Occupational Safety and Health (NIOSH) ISL fixture. Four hearing protection conditions were tested: Combat Arms earplug with the valve open, ETYPlugs ® earplug, TacticalPro headset, and a dual-protector ETYPlugs earplug with TacticalPro earmuff. The IPILs measured for the E-A-RCAL fixture were 1.4 dB greater than the National Institute for Occupational Safety and Health (NIOSH) ISL ATF. For the E-A-RCAL ISL ATF, the left ear IPIL was 2.0 dB greater than the right ear IPIL. For the NIOSH ATF, the right ear IPIL was 0.3 dB greater than the left ear IPIL.

[The potential of tone audiometry for the determination of the sound-absorbing properties of various materials].

The objective of the present work was to experimentally estimate the potential of the tone audiometry technique for the determination of the sound-absorbing properties of various material. The study included 15 subjects at the age from 19 to 32 years. Their audiological examination was followed by the placement of the 5×7 cm spacer plate from the study material beneath the bone vibrator telephone to determine the bone sound-conduction threshold; no air-marking was undertaken. The sound absorption by the study materials of interest was determined in each octave-band from 250 to 8000 Hz from the difference between the starting audiogram and the audiogram of the material of interest. The study was carried out in three stages: (1) evaluation of sound absorption of each of the five materials, (2) measurement of the same parameter in the combinations of 2--4 layers for increasing sound absorption, and (3) fixation of the bone conduction telephone by the operator's hand (the head-mounted harness was used for the same purpose at stages 1 and 2). The experiments demonstrated that the study of bone sound conduction by means of tone audiometry allows to estimate the sound absorption of various materials. This technique may be applied for the development of a subjective method for the measurement of sound absorption in order to evaluate the acoustic effectiveness of materials that can be used to construct individual protective anti-noise devices.

[The autonomic system reactivity of airport technical personnel using individual protective devices against noise].

The study covered cardiac rhythm variability and hemodynamic parameters in airfield technical personnel under exposure to aviation noise and with use of individual protective measures against noise. Individual protective means remove unfavorable stressful external effects of noise--that is manifested by more stable parameters of sympathetic nervous system activity.

Does modern helicopter construction reduce noise exposure in helicopter rescue operations?

BACKGROUND: During helicopter rescue operations the medical personnel are at high risk for hearing damage by noise exposure. There are two important factors to be taken into account: first, the extreme variability, with some days involving no exposure but other days with extreme exposure; second, the extreme noise levels during work outside the helicopter, e.g. during winch operations. The benefit of modern, less noisier constructions and the consequences for noise protection are still unknown. OBJECTIVES: We estimated the noise exposure of the personnel for different helicopter types used during rescue operations in the Alps and in other regions of the world with special regard to the advanced types like Eurocopter EC 135 to compare the benefit of modern constructions for noise protection with earlier ones. METHODS: The rescue operations over 1 year of four rescue bases in the Alps (Raron and Zermatt in Switzerland; Landeck and Innsbruck in Austria, n = 2731) were analyzed for duration of rescue operations (noise exposure). Noise levels were measured during rescue operations at defined points inside and outside the different aircraft. The setting is according to the European standard (Richtlinie 2003/10/EG Amtsblatt) and to Class 1 DIN/IEC 651. With both data sets the equivalent noise level L(eq8h) was calculated. For comparison it was assumed that all rescue operations were performed with a specific type of helicopter. Then model calculations for noise exposure by different helicopter types, such as Alouette IIIb, Alouette II 'Lama', Ecureuil AS350, Bell UH1D, Eurocopter EC135, and others were performed. RESULTS AND CONCLUSIONS: Depending on modern technologies the situation for the personnel has been improved significantly. Nevertheless noise prevention, which includes noise intermissions in spare time, is essential. Medical checks of the crews by occupational medicine (e.g. 'G20' in Germany) are still mandatory.

Consistency of attenuation across multiple fittings of custom and non-custom earplugs.

Hearing protection devices (HPDs) play a significant role in protecting workers from occupational noise-induced hearing loss. Individual HPD fit-testing estimates the amount of protection, or attenuation, that an individual achieves from a given HPD as it is worn. Results from a single fit-test may not be representative of real-world HPD performance over time, however, due to inconsistency in how the individual fits the HPD from time to time. In this study, the effects of HPD type and user training on the consistency of attenuation achieved across multiple fittings were evaluated in a within-subjects design. Attenuation measurements using a real-ear attenuation at threshold procedure were obtained on 30 participants wearing custom-molded and non-custom earplugs. The subjects were initially naive to proper earplug insertion techniques and later received one-on-one training for the second half of the attenuation measurements. Consistency, or reliability, of fit was assessed using (i) the standard deviation of the 'distance to ear mean attenuation', a measure of fitting uncertainty, and (ii) the standard deviation of the attenuation values across multiple fit-tests for each subject. The custom earplug provided statistically significantly better consistency of attenuation than the non-custom earplug at 500, 1000, and 2000 Hz. Training effects were statistically significant at 250, 500, and 1000 Hz and at the Personal Attenuation Rating. No interactions were statistically significant. These results indicate that, in general, subjects obtained more consistent attenuation with the custom earplugs than with the non-custom earplugs and that consistency improved with training for both earplug types.

Determining attenuation of impulse noise with an electrical equivalent of a hearing protection device.

Determining the effectiveness of impulse noise attenuation with hearing protection devices (HPDs) is an important part of their selection. Measuring impulse noise parameters under an HPD would involve exposing subjects to impulses with a high peak sound pressure level. This paper presents a computational method of determining impulse noise parameters under the cups of earmuffs. Calculations are done using the transfer function of earmuffs, determined with Shaw's electrical equivalent of an HPD, taking into account the design parameters of earmuffs. The developed method was used for calculations in the presence of impulse noise generated by gunshots. To verify the computational method, the results of these calculations were compared with the results of measurements.

Measurement of hearing protection devices performance in the workplace during full-shift working operations.

OBJECTIVES: The effectiveness of hearing protection devices (HPDs), when used in workplace conditions, has been shown over the years to be usually lower than the labeled values obtained under well-controlled laboratory conditions. Causes for such discrepancies have been listed and discussed by many authors. This study is an attempt to understand the issues in greater details and quantify some of these factors by looking at the performance of hearing protectors as a function of time during full work shift conditions. METHODS: A non-invasive field microphone in the real ear (F-MIRE)-based method has been developed for measuring the effectiveness of different HPDs as a function of time in the workplace. Details of the test procedures, the equipment used, and the post-processing operations are presented and discussed. The methodology was developed in such a way that a complete time and frequency representation are possible. The system was used on a total of 24 workers in eight different companies. Work shifts of up to 9-h long were recorded. Various types of earmuffs and one type of molded earplugs were tested. RESULTS: Attenuation data reported as a function of time showed, for most workers tested, considerable fluctuations over entire work shift periods. Parts of these fluctuations are attributed to variations in the low-frequency content in the noise (in particular for earmuffs) as well as poor insertion and/or fitting of earplugs. Lower performances than laboratory-based ones were once again observed for most cases tested but also, important left and right ear differences were obtained for many individuals. When reported as a function of frequency, the attenuation results suggested that the few approximations used to relate the measurements to subjective real-ear-attenuation-at-threshold (REAT) data were realistic. CONCLUSIONS: The use of individualized attenuation data and performance ratings for HPDs as well as a good knowledge of the ambient noise in the workplace are key ingredients when evaluating the performance of hearing protectors in field conditions.

Usability of a daily noise exposure monitoring device for industrial workers.

OBJECTIVES: Usability is an important but often overlooked aspect of personal protective equipment technology. As part of a worksite intervention trial of a new technology for prevention of noise-induced hearing loss that allows workers to monitor their noise exposure inside of hearing protection on a daily basis, we studied the usability of the daily noise exposure monitoring device. METHODS: We conducted surveys and focus groups for workers enrolled in an intervention trial of daily use of a noise dosimeter with a microphone fitted inside of an individual's hearing protector (QuietDose). Volunteers completed a baseline and annual survey that included questions about perceived usability of the QuietDose device. Responses to usability questions on the annual survey were abstracted and compared to whether the individual was still using the device. Finally, 16 in-depth focus groups were conducted with subjects to qualitatively explore common themes regarding the usability of the technology. RESULTS: Reported problems downloading data or starting and stopping the monitoring device and/or ear discomfort were associated with whether individuals chose to continue monitoring and downloading their noise exposure data. Perceived benefits of the technology included the perception that it could help preserve hearing. CONCLUSIONS: A novel technology that allows workers to record noise exposures inside of hearing protectors on a daily basis has been developed. Current users of the device report positive perception about how the device is helping them prevent noise-induced hearing loss. However, in its current version, users reported a number of usability barriers that are associated with stopping use of the device. These barriers to use should be addressed as the technology progresses.

Measurements of earplug attenuation under supra-aural and circumaural headphones.

OBJECTIVE: Supra-aural audiometric headphones are generally not recommended for use in measuring the attenuation of earplugs, because contact between the headphone and pinna and/or earplug could alter the attenuation obtained, and because of concerns of non-comparability between modes of excitation from supra-aural headphones and the sound-field procedure required by the standardized method. In this study, we compared measurements of earplug attenuation obtained under Telephonics TDH-50P supra-aural headphones with measurements obtained under circumaural headphones designed expressly for such testing. DESIGN: The attenuation of three types of earplugs (foam, premolded quadruple-flange, and custom-molded) was measured in a repeated-measures design. STUDY SAMPLE: The study sample comprised 42 normal-hearing adults (21 females, 21 males). RESULTS: With the foam earplugs, nearly all of the attenuation measurements under the supra-aural headphones fell within 10 dB of the measurements under the circumaural headphones. With the flange and custom earplugs, approximately 10% of individuals obtained spuriously high attenuation under the supra-aural headphones. CONCLUSIONS: We conclude that standard supra-aural audiometric headphones are suitable for measuring the attenuation provided by foam earplugs. However, supra-aural headphones should not be used to measure the attenuation of flange or custom-molded earplugs. The potential exists for substantial over-estimation of attenuation, especially of custom plugs.

Measurement of impulse peak insertion loss for four hearing protection devices in field conditions.

OBJECTIVE: In 2009, the U.S. Environmental Protection Agency (EPA) proposed an impulse noise reduction rating (NRR) for hearing protection devices based upon the impulse peak insertion loss (IPIL) methods in the ANSI S12.42-2010 standard. This study tests the ANSI S12.42 methods with a range of hearing protection devices measured in field conditions. DESIGN: The method utilizes an acoustic test fixture and three ranges for impulse levels: 130-134, 148-152, and 166-170 dB peak SPL. For this study, four different models of hearing protectors were tested: Bilsom 707 Impact II electronic earmuff, E·A·R Pod Express, E·A·R Combat Arms version 4, and the Etymotic Research, Inc. Electronic BlastPLG™ EB1. STUDY SAMPLE: Five samples of each protector were fitted on the fixture or inserted in the fixture's ear canal five times for each impulse level. Impulses were generated by a 0.223 caliber rifle. RESULTS: The average IPILs increased with peak pressure and ranged between 20 and 38 dB. For some protectors, significant differences were observed across protector examples of the same model, and across insertions. CONCLUSIONS: The EPA's proposed methods provide consistent and reproducible results. The proposed impulse NRR rating should utilize the minimum and maximum protection percentiles as determined by the ANSI S12.42-2010 methods.