Infection Prevention and the Protective Effects of Unidirectional Displacement Flow Ventilation in the Turbulent Spaces of the Operating Room.

BACKGROUND: Unidirectional displacement flow (UDF) ventilation systems in operating rooms are characterized by a uniformity of velocity ≥80% and protect patients and operating room personnel against exposure to hazardous substances. However, the air below the surgical lights and in the surrounding zone is turbulent, which impairs the ventilation system's effect. AIM: We first used the recovery time (RT) as specified in International Organization for Standardization 14644 to determine the particle reduction capacity in the turbulent spaces of an operating room with a UDF system. METHODS: The uniformity of velocity was analyzed by comfort-level probe grid measurements in the protected area below a hemispherical closed-shaped and a semi-open column-shaped surgical light (tilt angles: 0°/15°/30°) and in the surrounding zone of a research operating room. Thereafter, RTs were calculated. RESULTS: At a supply air volume of 10,500 m3/h, the velocity, reported as average uniformity ± standard deviation, was uniform in the protected area without lights (95.8% ± 1.7%), but locally turbulent below the hemispherical closed-shaped (69.3% ± 14.6%), the semi-open column-shaped light (66.9% ± 10.9%), and in the surrounding zone (51.5% ± 17.6%). The RTs ranged between 1.1 and 1.7 min below the lights and 3.5 ± 0.28 min in the surrounding zone and depended exponentially on the volume flow rate. CONCLUSIONS: Compared to an RT of ≤20 min as required for operating rooms with mixed dilution flow, particles here were eliminated 12-18 times more quickly from below the surgical lights and 5.7 times from the surrounding zone. Thus, the effect of the lights was negligible and the UDF's retained its strong protective effect.

The validity of using a self-report single question as a means to detect hearing loss in an adolescent population.

OBJECTIVE: The overall objective in the study was to compare self-reported hearing based on a single question ("how good would you currently rate your hearing?") to measure hearing loss determined by audiometry in a cohort of adolescents. Prevalence of audiometrically measured hearing loss and frequencies of self-reported poor hearing as well as factors that have an impact on self-reported hearing were examined. DESIGN: Baseline and 5-year follow-up data of the Ohrkan study were used. Participants filled in a questionnaire and underwent audiometric measurements. STUDY SAMPLE: Data from 979 adolescents were analysed. Participants were 54.7% female and aged between 13 and 18 years at baseline and 17-21 years at 5-yr follow-up. RESULTS: The single question on self-reported hearing ability achieved a sensitivity of 41.9% and a positive predictive value of 7.1% at baseline. For the 5-yr follow-up, sensitivity was 40.0%, positive predictive value was 13.9%. Factors influencing self-reported poor hearing were gender, tinnitus, "muffled" ears after exposure to loud noise (e.g. after a concert) and low-frequency hearing loss. CONCLUSIONS: The single question about hearing ability used in the Ohrkan study is not sufficient to replace audiometry to detect hearing loss as defined in the study in adolescents.

A multi-layered strategy for COVID-19 infection prophylaxis in schools: A review of the evidence for masks, distancing, and ventilation.

Implications for the academic and interpersonal development of children and adolescents underpin a global political consensus to maintain in-classroom teaching during the ongoing COVID-19 pandemic. In support of this aim, the WHO and UNICEF have called for schools around the globe to be made safer from the risk of COVID-19 transmission. Detailed guidance is needed on how this goal can be successfully implemented in a wide variety of educational settings in order to effectively mitigate impacts on the health of students, staff, their families, and society. This review provides a comprehensive synthesis of current scientific evidence and emerging standards in relation to the use of layered prevention strategies (involving masks, distancing, and ventilation), setting out the basis for their implementation in the school environment. In the presence of increasingly infectious SARS-Cov-2 variants, in-classroom teaching can only be safely maintained through a layered strategy combining multiple protective measures. The precise measures that are needed at any point in time depend upon a number of dynamic factors, including the specific threat-level posed by the circulating variant, the level of community infection, and the political acceptability of the resultant risk. By consistently implementing appropriate prophylaxis measures, evidence shows that the risk of infection from in-classroom teaching can be dramatically reduced. Current studies indicate that wearing high-quality masks and regular testing are amongst the most important measures in preventing infection transmission; whilst effective natural and mechanical ventilation systems have been shown to reduce infection risks in classrooms by over 80%.

The Relevance of Leisure Noise to Hearing Threshold Shifts: A Longitudinal Analysis Among Adolescents.

PURPOSE: The aim of this study was to analyze the association of total leisure noise exposure and hearing threshold shifts over 5 years among adolescents enrolled in the Ohrkan cohort study. METHOD: The Ohrkan cohort of 2,148 students aged 13-19 years was recruited from 2009 to 2011 and followed up 5 years later. Complete baseline and follow-up reports on exposure and outcome were available for 989 participants. Leisure noise exposure was assessed by questionnaires, and clinical audiometric examinations were performed. Two outcomes were defined: occurrence of the Niskar notch pattern and audiometry showing maximum hearing threshold values at 3, 4, and 6 kHz (both ears). Longitudinal analysis using generalized estimating equations was performed. RESULTS: High total leisure noise exposure, defined as an energy equivalent of a 40-hr week of > 85 dBA, was estimated for 32.7% of students at baseline and 63.8% at follow-up. A noise notch was observed in 1.1% of adolescents at baseline and 3.3% at follow-up. At baseline, the maximum measured threshold shift was 55 dB, which increased to 85 dB at the follow-up. Longitudinal analysis did not reveal an association between leisure noise exposure and hearing thresholds. Hearing threshold shifts or noise notches were associated with sex, school type, and time point of measurement. CONCLUSIONS: No relationship was found between leisure noise and hearing thresholds. Male adolescents and those attending secondary general schools, with graduation following completion of ninth or 10th grade, had a greater likelihood of developing hearing threshold shifts. Prevention programs should focus on these risk groups. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.19233462.

Exposure to leisure noise and intermittent tinnitus among young adults in Bavaria: longitudinal data from a prospective cohort study.

OBJECTIVES: To investigate the association between total leisure noise exposure and intermittent tinnitus among young adults. DESIGN: Data were obtained from the Ohrkan study, an ongoing prospective cohort study conducted in South Germany since 2009. Information about exposure to impulse and leisure noise, tinnitus occurrences, sociodemographic variables, and self-rated hearing ability were analysed at four time points over a period of seven and a half years. STUDY SAMPLE: Participants of the Ohrkan cohort study, who provided data about the occurrence of tinnitus for all surveys (n = 1028). RESULTS: Intermittent tinnitus was reported in the majority of the sample (60%). The risk for intermittent tinnitus increased with higher sound pressure levels from exposure to leisure noise (full model (Odds Ratio, 95%CI): 80-<85dB(A): 1.41 [1.13-1.78], 85-<90dB(A): 1.73 [1.38-2.16], >90dB(A): 2.04 [1.59-2.61]). Visiting nightclubs was a major contributor to this relationship. Of the considered covariables, self-rated hearing as "poor", and growing up in a single-parent household were significantly associated with intermittent tinnitus. CONCLUSION: Intermittent tinnitus is very frequent among young adults and is associated with high levels of leisure noise exposure. To prevent intermittent tinnitus, reduced sound pressure levels and the use of hearing protection are necessary.

Compensating for missing data in the OHRKAN cohort study examining total leisure noise exposure among adolescents.

OBJECTIVE: Investigating determinants of total leisure noise (TLN) exposure among adolescents over 7.5 years and compensating for missing data due to loss to follow-up. DESIGN: In the OHRKAN cohort study, data were collected by questionnaires at four waves. TLN was calculated from self-reported duration spent participating in 18 leisure activities. High exposure was defined as exceeding 85 dB(A) of equivalent continuous average sound pressure level (SPL) during a 40-h week. Multiple imputation (MI) and generalised estimating equations (GEE) were used to analyse odds ratios (OR) of determinants of TLN exposure and compared to complete-case analysis. STUDY SAMPLE: Closed cohort of 2148 students enrolled in grade 9 of any school in Regensburg (Germany), recruited from 2009 to 2011. RESULTS: Up to 74% of adolescents had risky TLN exposure, depending on wave. The most significant sources were discotheques, portable listening devices (PLD) and stereo systems. Higher TLN exposure was associated with time point, education, single-parent households and gender. MI under MAR assumption changed results only slightly compared to complete-case analysis. CONCLUSIONS: Prevalence of risky TLN is high during adolescence. MI reinforced trends detected in former results of OHRKAN. Preventive measures should consider the main drivers of noise exposure including changes by age and high risks groups.

Conventional versus notch filter amplification for the treatment of tinnitus in adults with mild-to-moderate hearing loss.

INTRODUCTION: Conventional hearing aids are commonly recommended for the treatment of tinnitus, though results of studies investigating the efficacy of hearing aid-based tinnitus treatments have been mixed. Recently, it has been suggested that the addition of a notch filter around the tinnitus frequency might enhance lateral inhibitory mechanisms and thereby improve tinnitus severity relative to traditional processing. The primary aim of this study was to compare the effects of conventional versus notch filter amplification strategies on subjective tinnitus severity in adults with mild-to-moderate hearing loss and no previous hearing aid experience. METHODS: Thirty-nine adults (mean age=53.6 years; SD=9.7 years) with bilateral, mild to moderate sensorineural hearing loss and an established clinical history of stable, tonal tinnitus participated in this double-blinded study. Each participant was randomly assigned to complete a 12-week hearing aid trial using either a conventional amplification strategy or a strategy which applied a notch filter at the given participant's tinnitus pitch match frequency. Tinnitus-related handicap and distress were assessed before and after the hearing aid trial via the Tinnitus Handicap Inventory (Newman et al., 1996) and the Tinnitus Questionnaire (Hallam et al., 1988). RESULTS: Average tinnitus severity did not differ significantly between the conventional and notch filter amplification groups following treatment. Moreover, average pre- to post-intervention change scores were relatively low for both groups, indicating minimal effect of either treatment on tinnitus symptoms. Participant age, high-frequency pure-tone average hearing threshold, average daily hearing aid usage, and pre-intervention tinnitus severity ratings were not predictive of treatment success or failure. DISCUSSION: Results of the present study suggest no significant effect of either conventional or notch filter amplification on average ratings of tinnitus severity following a 12-week hearing aid trial. However, as clinically meaningful changes in tinnitus severity were identified for some participants, future work is needed to better identify those individuals most likely to benefit, as well as optimal amplification characteristics.

Activating a Noise-Gating Algorithm and Personalizing Electrode Threshold Levels Improve Recognition of Soft Speech for Adults With CIs.

OBJECTIVE: In contrast to the moderate presentation levels most commonly used in clinical practice, speech encountered in everyday life often occurs at low levels, such as when a conversational partner whispers or speaks from another room. In addition, even when the overall signal level is moderate, levels for particular words or speech sounds, such as voiceless consonants, can be considerably lower. Existing techniques for improving recognition of low-level speech for cochlear implant users include using a wider input dynamic range and elevating electrode threshold levels (T-levels). While these techniques tend to positively impact recognition of soft speech, each has also been associated with drawbacks. Recently, a noise-gating (NG) algorithm was reported, which works by eliminating input to an electrode when signal level in the associated frequency channel is at or below a predetermined threshold. Available evidence suggests that activation of this algorithm can improve recognition of sentences presented at low levels (35 to 50 dB SPL), though it remains unclear whether the benefits will be equally evident with both manufacturer default and individually optimized T-levels. The primary aim of this study was therefore to evaluate the independent and combined effects of NG activation and T-level personalization. METHODS: Twenty adults between the ages of 25 and 77 years (M = 54.9 years, SD = 17.56) with postlingually acquired profound hearing loss completed testing for this study. Participants were fit with an Advanced Bionics Naida CI Q90 speech processor, which contained four programs based on each participant's existing everyday program. The programs varied by the NG algorithm setting (on, off) and T-level method (default 10% of M-level, personalized based on subjective ratings of "very quiet"). All participants completed speech sound detection threshold testing (/m/, /u/, /a/, /i/, /s/, and /∫/), as well as tests of monosyllabic word recognition in quiet (45 and 60 dB SPL), sentence recognition in quiet (45 and 60 dB SPL), and sentence recognition in noise (45-dB SPL speech, +10 dB SNR). RESULTS: Findings demonstrated that both activating NG and personalizing T-levels in isolation significantly improved detection (speech sounds) and recognition (monosyllables, sentences in quiet, and sentences in noise) of soft speech, with their respective individual effects being comparable. However, the lowest speech sound detection thresholds and the highest speech recognition performance were identified when NG was activated in conjunction with personalized T-levels. Importantly, neither T-level personalization nor NG activation affected recognition of speech presented at 60 dB SPL, which suggests the strategies should not be expected to interfere with recognition of average conversational speech. CONCLUSIONS: Taken together, these data support the clinical recommendation of personalizing T-levels and activating NG to improve the detection and recognition of soft speech. However, future work is needed to evaluate potential limitations of these techniques. Specifically, speech recognition testing should be performed in the presence of diverse noise backgrounds and home-trials should be conducted to determine processing effects on sound quality in realistic environments.

A clinical comparison of DPOAE fine structure reduction methods.

OBJECTIVE: To evaluate two real-time methods for reducing distortion product otoacoustic emission (DPOAE) fine structure in terms of DPOAE amplitude and fine structure depth. DESIGN: A prospective, repeated-measures design was used to assess DPOAE characteristics in response to a conventional stimulation method (Conv.), as well as for methods implementing either a generic suppressor tone (Supp.) or frequency modulation of the f2 primary tone (FM). STUDY SAMPLE: Eighty-three young adults (58 females) between the ages of 20 and 34 years with normal hearing completed testing for this study. RESULTS: Use of the Conv. and FM methods resulted in consistently higher DPOAE levels relative to the Supp. method, with average advantages of 6 and 5 dB, respectively. For all methods, increased fine structure depth was observed for stimulation with lower level (25-45 dB SPL) and lower frequency (1000-3000 Hz) primary tones. Finally, use of the Supp. and FM methods resulted in significantly decreased fine structure depth relative to the Conv. method. CONCLUSION: Through frequency modulation of the f2 primary tone, it was possible to reduce the depth of fine structure across a clinically meaningful range of stimulation levels and frequencies without concomitant reduction in DPOAE amplitude.

Chance-level hit rates in closed-set, forced-choice audiometry and a novel utility for the significance test-based detection of malingering.

The primary aim of this study was to extend existing theory on the relationship between chance-level performance and the number of alternatives and trials in closed-set, forced-choice speech audiometry and sound localization methods. When calculating chance performance for closed-set, forced-choice experiments with multiple trials, the binomial distribution should be preferred over the simple 1/a probability, as the latter is appropriate only for single trial experiments. The historical use of constant hit rates for determining chance performance has been based upon the assumption that random hits are distributed evenly across multiple trials. For any closed-set, forced-choice task with 2 to 10 alternatives and 2 to 100 trials, we calculated the probability of obtaining any given hit rate due to random guessing alone according to the binomial distribution. Hit rates with probabilities p > 0.05 were interpreted as being likely to occur due to random chance alone, whereas hit rates with probabilities of p ≤ 0.05 were interpreted as being unlikely to occur due to chance alone. For sound localization experiments with speakers at fixed positions, the expected probability of a random hit was also calculated using the binomial distribution. The expected angular root mean square (rms) error in sound localization resulting from the random selection of sound sources was investigated using Monte Carlo simulations. A new aspect in the interpretation of test results was identified for situations in which the observed number of hits is much lower than would be expected due to chance alone. For test methods incorporating a relatively low number of alternatives and a sufficiently high, yet clinically feasible, number of trials, both upper and lower thresholds for chance-level performance could be identified. This lower threshold represents the lowest hit rate which can be expected through random chance alone. Extending interpretation of results to include this lower threshold affords the ability to not only identify performance significantly superior to that of chance, but also that significantly poorer than chance and thereby represents a simple method for the objective detection of malingering.

Semantic segmentation of synchrotron tomography of multiphase Al-Si alloys using a convolutional neural network with a pixel-wise weighted loss function.

Human-based segmentation of tomographic images can be a tedious time-consuming task. Deep learning algorithms and, particularly, convolutional neural networks have become state of the art techniques for pattern recognition in digital images that can replace human-based image segmentation. However, their use in materials science is beginning to be explored and their application needs to be adapted to the specific needs of this field. In the present work, a convolutional neural network is trained to segment the microstructural components of an Al-Si cast alloy imaged using synchrotron X-ray tomography. A pixel-wise weighted error function is implemented to account for microstructural features which are hard to identify in the tomographs and that play a relevant role for the correct description of the 3D architecture of the alloy investigated. The results show that the total operation time for the segmentation using the trained convolutional neural network was reduced to <1% of the time needed with human-based segmentation.

Radiographic image interpretation by Australian radiographers: a systematic review.

INTRODUCTION: Radiographer image evaluation methods such as the preliminary image evaluation (PIE), a formal comment describing radiographers' findings in radiological images, are embedded in the contemporary radiographer role within Australia. However, perceptions surrounding both the capacity for Australian radiographers to adopt PIE and the barriers to its implementation are highly variable and seldom evidence-based. This paper systematically reviews the literature to examine radiographic image interpretation by Australian radiographers and the barriers to implementation. METHODS: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses were used to systematically review articles via Scopus, Ovid MEDLINE, PubMed, ScienceDirect and Informit. Articles were deemed eligible for inclusion if they were English language, peer-reviewed and explored radiographic image interpretation by radiographers in the context of the Australian healthcare system. Letters to the editor, opinion pieces, reviews and reports were excluded. RESULTS: A total of 926 studies were screened for relevance, 19 articles met the inclusion criteria. The 19 articles consisted of 11 cohort studies, seven cross-sectional surveys and one randomised control trial. Studies exploring radiographers' image interpretation performance utilised a variety of methodological designs with accuracy, sensitivity and specificity values ranging from 57 to 98%, 45 to 98% and 68 to 98%, respectively. Primary barriers to radiographic image evaluation by radiographers included lack of accessible educational resources and support from both radiologists and radiographers. CONCLUSION: Australian radiographers can undertake PIE; however, educational and clinical support barriers limit implementation. Access to targeted education and a clear definition of radiographers' image evaluation role may drive a wider acceptance of radiographer image evaluation in Australia.

Photoacoustic gas monitoring for anesthetic gas pollution measurements and its cross-sensitivity to alcoholic disinfectants.

BACKGROUND: Real-time photoacoustic gas monitoring is used for personnel exposure and environmental monitoring, but its accuracy varies when organic solvents such as alcohol contaminate measurements. This is problematic for anesthetic gas measurements in hospitals, because most disinfectants contain alcohol, which could lead to false-high gas concentrations. We investigated the cross-sensitivities of the photoacoustic gas monitor Innova 1412 (AirTech Instruments, LumaSense, Denmark) against alcohols and alcoholic disinfectants while measuring sevoflurane, desflurane and isoflurane in a laboratory and in hospital during surgery. METHODS: 25 mL ethyl alcohol was distributed on a hotplate. An optical filter for isoflurane was used and the gas monitor measured the 'isoflurane' concentration for five minutes with the measuring probe fixed 30 cm above the hotplate. Then, 5 mL isoflurane was added vaporized via an Anesthetic Conserving Device (Sedana Medical, Uppsala, Sweden). After one-hour measurement, 25 mL isopropyl alcohol, N-propanol, and two alcoholic disinfectants were subsequently added, each in combination with 5 mL isoflurane. The same experiment was in turn performed for sevoflurane and desflurane. The practical impact of the cross-sensitivity was investigated on abdominal surgeons who were exposed intraoperatively to sevoflurane. A new approach to overcome the gas monitor's cross-sensitivity is presented. RESULTS: Cross-sensitivity was observed for all alcohols and its strength characteristic for the tested agent. Simultaneous uses of anesthetic gases and alcohols increased the concentrations and the recovery times significantly, especially while sevoflurane was utilized. Intraoperative measurements revealed mean and maximum sevoflurane concentrations of 0.61 ± 0.26 ppm and 15.27 ± 14.62 ppm. We replaced the cross-sensitivity peaks with the 10th percentile baseline of the anesthetic gas concentration. This reduced mean and maximum concentrations significantly by 37% (p < 0.001) and 86% (p < 0.001), respectively. CONCLUSION: Photoacoustic gas monitoring is useful to detect lowest anesthetic gases concentrations, but cross-sensitivity caused one third falsely high measured mean gas concentration. One possibility to eliminate these peaks is the recovery time-based baseline approach. Caution should be taken while measuring sevoflurane, since marked cross-sensitivity peaks are to be expected.

Subclinical conductive hearing loss significantly reduces otoacoustic emission amplitude: Implications for test performance.

OBJECTIVES: Distortion product otoacoustic emissions (DPOAEs) are a time-efficient, non-invasive means of assessing the integrity of active inner ear mechanics. Unfortunately, the presence of even relatively minor conductive hearing loss (CHL) has been suggested to reduce the clinical utility of DPOAEs significantly. The primary aims of this study were to systematically evaluate the impact of CHL on DPOAE amplitude and to determine if ear-specific primary tone level manipulations can be used to mitigate CHL impact and recover DPOAE measurability. METHODS: For 30 young adults (57 ears) with normal hearing, DPOAEs were obtained for f2 = 1-6 kHz. Observed DPOAE amplitudes were used to generate ear- and frequency-specific models with the primary tone levels, L1 and L2, as inputs and predicted DPOAE amplitude, LDP, as output. These models were then used to simulate the effect of CHL (0-15 dB), as well as L1 manipulations (0-15 dB), on DPOAE measurability. RESULTS: Mean LDP for every CHL condition was significantly different from that for all other conditions (p = <.001), with a mean LDP attenuation of 8.7 dB for every 5 dB increase in CHL. Mean DPOAE measurability in response to a standard clinical stimulation paradigm of L1/L2 = 65/55 (dB SPL) was determined to be 99%, 84%, 37%, and 9% in the presence of 0, 5, 10, and 15 dB CHL, respectively. In the presence of 10 dB CHL, altering L1 resulted in an approximately 25% increase in DPOAE responses. CONCLUSION: Subclinical CHL loss is sufficient to significantly impair DPOAE measurability in a meaningful proportion of otherwise healthy ears. However, through strategic alteration of primary tone levels, the clinician can mitigate CHL impact and at least partially recover DPOAE measurability.

Feedback reduction system influence on additional gain before feedback and maximum stable gain in open-fitted hearing aids.

OBJECTIVE: The primary purpose of this study was to update existing data on additional gain before feedback and maximum stable gain in commercially available, open-fit hearing instruments. A secondary purpose was to evaluate ratings of sound quality with feedback reduction systems active. DESIGN: Additional gain before feedback, maximum stable gain and subjective sound quality ratings were obtained for six commercially available hearing instruments utilising modern feedback reduction systems. STUDY SAMPLE: Twenty adults (22-46 years) with normal hearing participated in gain measurement testing. Thirty adults (22-39 years) with normal hearing provided ratings of sound quality. RESULTS: Mean additional gain before feedback for 2000-4000 Hz ranged from 5 to 16 dB across manufacturers. Mean maximum stable gain in the same frequency region ranged from 25 to 35 dB across manufacturers. However, meaningful performance differences between participants within each given manufacturer were also identified. Sound quality ratings were not related to the type of feedback reduction algorithm. CONCLUSIONS: AGBF and MSG continue to vary significantly both across manufacturers as well as individual ears within a given manufacturer. User satisfaction and performance with hearing aids might be improved by identifying the feedback reduction system optimal for the individual patient.

Wideband Absorbance and 226-Hz Tympanometry in the Prediction of Optimal Distortion Product Otoacoustic Emission Primary Tone Levels.

PURPOSE: Distortion product otoacoustic emission (DPOAE) amplitude is sensitive to the primary tone level separation effective within the cochlea. Despite potential for middle ear sound transmission characteristics to affect this separation, no primary tone level optimization formula accounts for its influence. This study was conducted to determine if inclusion of ear- and frequency-specific immittance features improves primary tone level optimization formula performance beyond that achieved using a univariate, L2-based formula. METHOD: For 30 adults with normal hearing, DPOAE, wideband absorbance, and 226-Hz tympanometry measures were completed. A mixed linear modeling technique, incorporating both primary tone and acoustic immittance features, was used to generate a multivariable formula for the middle ear-specific recommendation of primary tone level separations for f2 = 1-6 kHz. The accuracy with which L1OPT, or the L1 observed to maximize DPOAE level for each given L2, could be predicted using the multivariable formula was then compared with that of a traditional, L2-based univariate formula for each individual ear. RESULTS: Use of the multivariable formula L1 = 0.47L2 + 2.40A + f2param + 38 [dB SPL] resulted in significantly more accurate L1OPT predictions than did the univariate formula L1 = 0.49L2 + 41 [dB SPL]. Although average improvement was small, meaningful improvements were identified within individual ears, especially for f2 = 1 and 6 kHz. CONCLUSION: Incorporation of a wideband absorbance measure into a primary tone level optimization formula resulted in a minor average improvement in L1OPT prediction accuracy when compared with a traditional univariate optimization formula. Further research is needed to identify characteristics of ears that might disproportionately benefit from the additional measure.

Longitudinal analysis of leisure noise exposure among adolescents with special focus on portable listening devices: the OHRKAN cohort study.

The aim was to investigate leisure noise exposure and sociodemographic determinants of risky leisure noise exposure over five years in 2148 students visiting grade 9 of any school type in a German city from 2009-2011. Within the OHRKAN cohort study, leisure noise exposure was calculated from literature-retrieved sound pressure levels (SPLs) and self-reported duration of 18 leisure activities at baseline and two follow-ups. Risky exposure was defined as exceeding 85 dB(A) averaged over a 40-h-week. Determinants of risky total leisure noise (TLN) exposure and risky exposure to portable listening devices (PLDs) were investigated using generalised estimating equations (GEEs). Up to 73% of students exceeded noise levels of 85 dB(A) at some timepoint. The noise exposure and importance of different leisure activities changed with increasing age. Risky exposure to TLN and PLDs was associated with lower education, single parent households and being male. Risky PLD exposure was additionally associated with a migrant background. Current prevention measures for leisure noise exposure must be extended to at-risk groups. Besides enhancing campaigns in lower education schools, acoustical insulation in sports halls, noise warnings on tools or in videogames could address especially men. Migrants need education about healthy PLD use in their native language if necessary.

Efficiencies and noise levels of portable surgical smoke evacuation systems.

Surgical smoke resulting from electrocauterization is a health risk for operating room personnel. The U.S. National Institute for Occupational Safety and Health recommends the use of local exhaust ventilation such as a portable smoke evacuation system to reduce surgical smoke, but its efficiency has never been assessed under experimental conditions. In this study, particle filtration efficiencies of five commercially available smoke evacuation systems were investigated in a model operating room. Two cutting angles, the devices' suction capacities, three unidirectional displacement flow rates, and the noise exposures were considered. Results demonstrated that portable smoke evacuation systems reduce surgical smoke up to 99% under optimal conditions. A cutting angle of 45°, the device's maximum suction capacity, and a unidirectional displacement flow rate of 10,500 m³/hr were advantageous. Sound levels ranged between 51-69 dBA and exceeded recommended threshold limits, if used with medium or maximum suction capacity. Hence, portable smoke evacuation systems are beneficial and are recommended. However, a combination with general unidirectional room ventilation and a strict limitation of the use of electrocauterization is strongly advised.

Revealing the Effect of Local Connectivity of Rigid Phases during Deformation at High Temperature of Cast AlSi12Cu4Ni(2,3)Mg Alloys.

The 3D microstructure and its effect on damage formation and accumulation during tensile deformation at 300 °C for cast, near eutectic AlSi12Cu4Ni2Mg and AlSi12Cu4Ni3Mg alloys has been investigated using in-situ synchrotron micro-tomography, complemented by conventional 2D characterization methods. An increase of Ni from 2 to 3 wt.% leads to a higher local connectivity, quantified by the Euler number χ, at constant global interconnectivity of rigid 3D networks formed by primary and eutectic Si and intermetallics owing to the formation of the plate-like Al-Ni-Cu-rich δ-phase. Damage initiates as micro-cracks through primary Si particles agglomerated in clusters and as voids at matrix/rigid phase interfaces. Coalescence of voids leads to final fracture with the main crack propagating along damaged rigid particles as well as through the matrix. The lower local connectivity of the rigid 3D network in the alloy with 2 wt.% Ni permits localized plastification of the matrix and helps accommodating more damage resulting in an increase of ductility with respect to AlSi12Cu4Ni3Mg. A simple load partition approach that considers the evolution of local connectivity of rigid networks as a function of strain is proposed based on in-situ experimental data.

Different Patterns of Hearing Loss among Tinnitus Patients: A Latent Class Analysis of a Large Sample.

BACKGROUND: The heterogeneity of tinnitus is a major challenge for tinnitus research. Even if a complex interaction of many factors is involved in the etiology of tinnitus, hearing loss (HL) has been identified as the most relevant etiologic factor. Here, we used a data-driven approach to identify patterns of hearing function in a large sample of tinnitus patients presenting in a tinnitus clinic. METHODS: Data from 2,838 patients presenting at the Tinnitus Center of the University Regensburg between 2007 and 2014 have been analyzed. Standard audiometric data were frequency-wise categorized in four categories [a: normal hearing (0-20 dB HL); b: moderate HL (25-50 dB HL; representing outer hair cell loss); c: severe HL (>50 dB HL; representing outer and inner hair cell loss); d: no data available] and entered in a latent class analysis, a statistical method to find subtypes of cases in multivariate categorical data. To validate the clinical relevance of the identified latent classes, they were compared with respect to clinical and demographic characteristics of their members. RESULTS: The classification algorithm identified eight distinct latent classes with an excellent separation. Patient classes differed with respect to demographic (e.g., age, gender) and clinical characteristics (e.g., tinnitus location, tinnitus severity, gradual, or abrupt onset, etc.). DISCUSSION: Our results demonstrate that data-driven categorization of hearing function seems to be a promising approach for profiling tinnitus patients, as it revealed distinct subtypes that reflect prototypic forms of HL and that differ in several relevant clinical characteristics.