Peak Sound Level Research Articles

Changes in Auditory Performance Following a Virtual Reality Music Concert.

The purpose of this study was to evaluate threshold and suprathreshold auditory risk from a newly popular platform of music concert entertainment; virtual reality (VR) headsets. Recreational noise exposure to music is the primary source of hearing hazard in young-adults, with noise doses of in-person concert venues and music festivals well in excess of the recommended daily exposure recommendation from the National Institute for Occupational Safety and Health. While research on the relationship between personal music players and noise-induced hearing loss risk is abundant, no study has yet evaluated noise-induced hearing loss risk from VR headsets, which are newest to the commercial market at this time. Thirty-one young-adult participants (18 to 25 years) with normal-hearing sensitivity (0 to 16 dB HL) experienced a VR music concert and participated in three data collection timepoints: Session A preexposure, Session A post-exposure, and Session B post-exposure. Participants underwent baseline testing for audiometry (0.25 to 20 kHz), distortion product otoacoustic emission testing (1 to 10 kHz), and Words-in-Noise testing. Participants then wore a commercially available VR headset (Meta Quest 2) and experienced a freely available online VR music concert (via the video-sharing website "YouTube"). The VR music concert duration was 90 min set to maximum volume, which yielded an average sound level equivalent of 78.7 dBA, max sound level of 88.2 dBA, and LC peak sound level of 98.6 dBA. Post-exposure testing was conducted immediately at the conclusion of the VR concert, and again within 24 hr to 1 week after the exposure. Participants also answered a questionnaire that estimated noise exposure history (National Acoustics Laboratory "Noise Calculator"). Post-exposure deficit was not observed in DPOAEs or Words-in-Noise score (p's > 0.05). However, statistically significant temporary post-exposure deficit was observed in audiometry at 4, 8, and 12.5 kHz (p's < 0.05) (mean differences: 2 to 3 dB HL). Twenty-four hours and 1-week post-exposure measurements revealed no permanent changes from baseline measurements (p's > 0.05) aside from one spurious difference at 12.5 kHz. Males tended to exhibit a significantly higher noise history score on average than females. The primary, secondary, and tertiary sources of noise hazard history in this young-adult cohort included amplified music. These preliminary data suggest that VR music concerts-which are likely to produce a substantially lower noise dose than in-person music concerts-may still be capable of producing at least slight, temporary threshold shifts on the order of 2 to 3 dB HL. Future research should include VR headsets in personal music player risk assessment, as the VR music concert platform is increasing rapidly in popularity among young-adults.

Evaluation of the sensory environment in a large tertiary ICU

BackgroundICU survival is improving. However, many patients leave ICU with ongoing cognitive, physical, and/or psychological impairments and reduced quality of life. Many of the reasons for these ongoing problems are unmodifiable; however, some are linked with the ICU environment. Suboptimal lighting and excessive noise contribute to a loss of circadian rhythms and sleep disruptions, leading to increased mortality and morbidity. Despite long-standing awareness of these problems, meaningful ICU redesign is yet to be realised, and the ‘ideal’ ICU design is likely to be unique to local context and patient cohorts. To inform the co-design of an improved ICU environment, this study completed a detailed evaluation of the ICU environment, focussing on acoustics, sound, and light.MethodsThis was an observational study of the lighting and acoustic environment using sensors and formal evaluations. Selected bedspaces, chosen to represent different types of bedspaces in the ICU, were monitored during prolonged study periods. Data were analysed descriptively using Microsoft Excel.ResultsTwo of the three monitored bedspaces showed a limited difference in lighting levels across the day, with average daytime light intensity not exceeding 300 Lux. In bedspaces with a window, the spectral power distribution (but not intensity) of the light was similar to natural light when all ceiling lights were off. However, when the ceiling lights were on, the spectral power distribution was similar between bedspaces with and without windows. Average sound levels in the study bedspaces were 63.75, 56.80, and 59.71 dBA, with the single room being noisier than the two open-plan bedspaces. There were multiple occasions of peak sound levels > 80 dBA recorded, with the maximum sound level recorded being > 105 dBA. We recorded one new monitor or ventilator alarm commencing every 69 s in each bedspace, with only 5% of alarms actioned. Acoustic testing showed poor sound absorption and blocking.ConclusionsThis study corroborates other studies confirming that the lighting and acoustic environments in the study ICU were suboptimal, potentially contributing to adverse patient outcomes. This manuscript discusses potential solutions to identified problems. Future studies are required to evaluate whether an optimised ICU environment positively impacts patient outcomes.

Long-Term Hearing Loss after Acute Acoustic Trauma inthe French Military: A Retrospective Study.

Acute acoustic trauma (AAT) is characterized by cochlea-vestibular signs following intense noise exposure, often caused by impulse noise. French military faces a high risk of AAT because of the use of weapons with peak sound levels exceeding 150 dB. Hearing loss (HL) resulting from AAT can have a significant impact on quality of life and operational capacity. The aim of this study was to assess the prevalence of long-term hearing impairment after AAT. The study involved a retrospective review of computer-based patient records from four military medical centers in Northeast France between January 2016 and December 2021. The inclusion criteria required the presence of cochlea-vestibular signs following impulse acoustic exposure and the absence of other causes. Sociodemographic and clinical data were collected, including audiometric data before and after exposure. The primary end point was the presence of a threshold elevation greater than 10 dB between reference and late audiograms. A total of 419 patients were included in the analysis, with a majority of males (n = 419; 84.7%) and a mean age of 23.6 yrs. The most common causative agent was the 5.56-mm assault rifle (n = 327; 78.0%). Tinnitus was the most frequent symptom (n = 366; 87.4%), followed by hypoacusis (n = 147; 35.1%) and earache (n = 89; 21.2%). The initial audiograms showed no HL in 31.0% of cases, while the mean deficit across all frequencies was 15.4 dB. All patients received corticosteroid therapy, with a mean duration of 6.0 d. Late audiograms conducted at an average interval of 448.0 d after AAT revealed a prevalence of long-term HL exceeding 20%. Higher doses of corticosteroid therapy (>1 mg/kg) were associated with a reduced frequency of long-term HL. This study highlights the prevalence of long-term hearing impairment after AAT in the French military. The findings emphasize the importance of preventive measures, including proper use of hearing protection devices, and the need for timely diagnosis and treatment. Further research is warranted to explore gender susceptibility to AAT and evaluate the impact of different weapons on AAT characteristics. The study also underscores the potential benefits of higher doses of corticosteroid therapy in reducing the risk of long-term hearing impairment. Overall, the findings contribute to a better understanding of AAT and can inform strategies for its prevention and management in military settings.

Noise exposure exceeded safe limits during neonatal care and road transport but was reduced by active noise cancelling.

Noise levels above 45 dB in a neonatal intensive care unit (NICU) and 60 dB during neonatal transport are recognised hazards, but protective equipment is not standard. We measured noise levels in both settings, with and without noise protection. Peak sound and equivalent continuous sound levels were measured in a NICU and during road transport, at a mannequin's ear and inside and outside the incubator. Recordings were made without protective earwear, with noise protecting earmuffs and with active noise cancelling headphones. In the NICU, the peak levels at the ear, and inside and outside the incubator, were 61, 68 and 76 dB. The equivalent continuous sound levels were 45, 54 and 59 dB. During road transport, the respective levels were 70, 77 and 83 dB and 54, 62 and 68 dB. In the NICU, 80% of environmental peak noise reached the ear and this was reduced to 78% with earmuffs and 75% with active noise cancelling. The respective figures during transport were 87% without protection and 72% with active noise cancelling, with an unexpected increase for ear muffs. Noise levels exceeded safe limits in the NICU and during transport, but active noise cancelling reduced exposure.

Sound-source distribution in the bogie section of a train determined by simultaneous measurement by pressure-sensitive paint and a microphone

Sound-pressure level of acoustic waves from the flow around a 1/8-reduced-scale simplified train model and pressure-fluctuation distribution of the bottom surface of the bogie were measured simultaneously by a microphone and a pressure-sensitive paint (PSP). A high-pressure-fluctuation area was observed on the upstream side on the bogie bottom surface at the peak sound frequency. The phase distribution of the peak frequency of the PSP data was observed to be uniform in the spanwise direction and delayed in the downstream direction. This result indicates that propagation speed of peak surface pressure fluctuation was 66 % of the freestream wind velocity. Thus, the measured peak sound frequency was found to be the same as the theoretical cavity peak frequency given by the Rossiter equation with that propagation speed as a vortex convection velocity. Therefore, the peak sound is concluded to be generated from acoustic feedback in the cavity, which is the gap between the upstream cavity edge and the bogie. Moreover, the difference between the measured and correlated peak sound levels of the bottom surface of the bogie, was no more than 3 dB, where the correlated sound level was calculated by using the Lighthill-Curle equation with coherent output power data.

High amplitude time reversal focusing of sound and vibration

Time reversal (TR) is a signal processing technique that can be used to focus high amplitude sound or vibration at a desired location. TR focusing can be done with sources placed far from the desired focal location and the technique excels in complex environments. The impulse response between each source and the desired focal location must be obtained prior to the focusing and the environment must remain relatively unchanged for successful focusing. Multiple scattering or reverberation of waves off of many reflecting surfaces in the environment can actually be used advantageously by exploiting those reflections as additional image sources. This talk will provide an introduction to TR and then focus on the use of TR to provide high amplitude focusing of sound and vibration. Applications of high amplitude TR include lithotripsy of kidney stones, histotripsy of lesions, and locating cracks and defects in structures such as in human teeth, spent nuclear fuel storage casks, airplane wings, and automotive bearing caps. Recently, high amplitude TR of airborne sound has been studied in a reverberation chamber to generate a focused difference frequency and to study the nonlinear acoustics of the peak sound levels of 200 dB that have been attained.

Effects of Live Music on the Perception of Noise in the SICU/PICU: A Patient, Caregiver, and Medical Staff Environmental Study.

Intensive Care Units (ICUs) require a multidisciplinary team that consists of, but is not limited to, intensivists (clinicians who specialize in critical illness care), pharmacists and nurses, respiratory care therapists, and other medical consultants from a broad range of specialties. The complex and demanding critical care environment provides few opportunities for patients and personal and professional caregivers to evaluate how sound effects them. A growing body of literature attests to noise's adverse influence on patients' sleep, and high sound levels are a source of staff stress, as noise is an ubiquitous and noxious stimuli. Vulnerable patients have a low threshold tolerance to audio-induced stress. Despite these indications, peak sound levels often register as high, as can ventilators, and the documented noise levels in hospitals continue to rise. This baseline study, carried out in two hospitals' Surgical and Pediatric Intensive Care Units, measured the effects of live music on the perception of noise through surveying patients, personal caregivers and staff in randomized conditions of no music, and music as provided by music therapists through our hospital system's environmental music therapy program.

Failed Attempt to Recommend Noise Cancelling Headphones for Knee Arthroplasty Surgeons-Results of a Pilot Study.

Background and Objectives: Noise exposure during total knee arthroplasty (TKA) has been demonstrated to exceed thresholds that are deemed as over-exposure by industry noise level standards. With orthopedic surgeons being at risk of suffering from Noise Induced Hearing Loss, the purpose of this pilot study was to evaluate the viability of the use of industry grade active noise cancelling headphones (ANCH) during TKA. Material and Methods: In this prospective pilot study, 10 TKA were performed. In five of these cases, surgeon, assistant, scrub nurse and anesthetist wore ANCH with automatic noise level dependent noise attenuation above 82 dB. A validated 14-item questionnaire was used after each case to evaluate the quality of communication, performance, teamwork and mental load. In seven cases a calibrated sound level meter was used to measure the operating theatre noise. Peak sound level (LApeak), A-weighted continuous sound level (LAeq) and A-weighted noise exposure averaged for an 8-h time-period (LEPd) were calculated. Results: There was no perceived benefit of ANCH for the surgeons (p = 0.648), assistants (p = 0.908) and scrub nurses (p = 0.251). There was an overall improvement observed by anesthetists (p = 0.001). A worse communication while wearing ANCH was reported by surgeons but not by the rest of the team. Average LApeak was 90.6 ± 3.2 dB(C), LAeq was 61.9 ± 1.0 dB(A) and LEPd was 53.2 ± 1.2 dB(A). Conclusions: Industry grade ANCH seem to provide no benefit for surgeons, assistants and scrub nurses during TKA, while anesthesiologists seem to benefit from the use of ANCH during TKA. Due to the limitations of this pilot study, further studies with larger study populations are necessary to adequately investigate the use of ANCH during TKA.

Psychophysiological responses to traffic noises in urban green spaces

The present study aims to explore the psychophysiological impact of different traffic sounds in urban green spaces. In the experiment, 30 subjects were recruited and exposed to different traffic sounds in the virtual reality (VR) scene. The road traffic sound and three railway sounds (con-ventional train, high-speed train, and tram) with three sound levels (45, 55, and 65 dB) were used as the acoustic stimuli. Physiological responses, electrodermal activity (EDA) and heart rate (HR) were monitored throughout the experiment. Psychological evaluations under each acoustic stimuli were also measured using scales within the VR system. The results showed that both the psychological and the physiological responses were significantly affected by the traffic sounds. As for psychological responses, considerable adverse effects of traffic sounds were observed, which constantly increased with the increase of the sound level. The peak sound level was found to have a better performance than the equivalent sound level in the assessment of the psycho-logical impact of traffic sounds. As for the physiological responses, significant effects of both the acoustic factors (sound type and sound level) and the non-acoustic factors (gender and exposure time) were observed. The physiological effect of high-speed train noise was significantly differ-ent from those of the other three traffic noises. The relationship between sound level and physi-ological parameters varied among different sound groups. The variation of sound level could hardly affect the participants' HR and EDA when exposed to the road traffic noise. On the con-trary, the physiological responses were significantly affected by the sound level of rail traffic noise. By a correlation analysis, no linear correlation between the psychological evaluations and HR was found.

Psychophysiological Impacts of Traffic Sounds in Urban Green Spaces

The goal of this study is to investigate the psychophysiological effects of traffic sounds in urban green spaces. In a laboratory experiment, psychological and physiological responses to four traffic sounds were measured, including road, conventional train, high-speed train, and tram. The findings demonstrated that traffic sounds had significant detrimental psychological and physiological effects. In terms of psychological responses, the peak sound level outperformed the equivalent sound level in determining the psychological impact of traffic sounds. The physiological effects of traffic sounds were shown to be significantly influenced by sound type and sound level. The physiological response to the high-speed train sound differed significantly from the other three traffic sounds. The physiological effects of road traffic sounds were found to be unrelated to the sound level. On the contrary, as for the railway sounds, the change in sound level was observed to have a significant impact on the participants’ physiological indicators.

Noise exposure during robot-assisted total knee arthroplasty

The aim of the study was to examine the noise exposure for operating theater staff during total knee arthroplasty (TKA) with three different robot systems. There is already evidence that noise exposure during TKA performed manually exceeds recommended guidelines for occupational noise. Therefore, if surgical staff is exposed to it for several years, the development of noise-inducing hearing loss (NIHL) is significantly increased. To investigate the noise exposure during robot-assisted TKA, the study measured the average noise and the peak sound pressure during TKA with MAKO robot (Stryker, Kalamazoo, Michigan, United States), NAVIO robot (Smith and Nephew, London, Great Britain), and CORI robot (Smith and Nephew, London, Great Britain) using a class 1 sound level meter. Each robot system exceeds the recommended guidelines from the national institute for occupational safety and health. While the MAKO robot had the highest average sound level (93.18 dB(A)) of the three robot systems (NAVIO: 88.88 dB(A), CORI: 89.38 dB(A)), the peak sound level was the highest with the NAVIO Robot (134.48 dB(C)) compared to the MAKO Robot (128.98 dB(C)) and CORI robot (126.48 dB(C)). Robot-assisted TKA is a risk factor for NIHL, like manually performed TKA. Further research for decreasing the noise exposure during TKA is needed to minimize the hearing loss in operating theater staff.

Guidelines for Diagnosing and Quantifying Noise-Induced Hearing Loss.

This paper makes recommendations for the diagnosis and quantification of noise-induced hearing loss (NIHL) in a medico-legal context. A distinction is made between NIHL produced by: steady broadband noise, as occurs in some factories; more impulsive factory sounds, such as hammering; noise exposure during military service, which can involve very high peak sound levels; and exposure to very intense tones. It is argued that existing diagnostic methods, which were primarily developed to deal with NIHL produced by steady broadband noise, are not adequate for the diagnosis of NIHL produced by different types of exposures. Furthermore, some existing diagnostic methods are based on now-obsolete standards, and make unrealistic assumptions. Diagnostic methods are proposed for each of the types of noise exposure considered. It is recommended that quantification of NIHL for all types of exposures is based on comparison of the measured hearing threshold levels with the age-associated hearing levels (AAHLs) for a non-noise exposed population, as specified in ISO 7029 (2017), usually using the 50th percentile, but using another percentile if there are good reasons for doing so. When audiograms are available both soon after the end of military service and some time afterwards, the most recent audiogram should be used for diagnosis and quantification, since this reflects any effect of the noise exposure on the subsequent progression of hearing loss. It is recommended that the overall NIHL for each ear be quantified as the average NIHL across the frequencies 1, 2, and 4 kHz.

Effect of Road and Railway Sound on Psychological and Physiological Responses in an Office Environment

The present study aims to explore the psychophysiological impact of different traffic sounds in office spaces. In this experiment, 30 subjects were recruited and exposed to different traffic sounds in a virtual reality (VR) office scene. The road traffic sound and three railway sounds (conventional train, high-speed train, and tram) with three sound levels (45, 55, and 65 dB) were used as the acoustic stimuli. Physiological responses, electrodermal activity (EDA) and heart rate (HR) were monitored throughout the experiment. Psychological evaluations under each acoustic stimulus were also measured using scales within the VR system. The results showed that both the psychological and the physiological responses were significantly affected by the traffic sounds. As for psychological responses, considerable adverse effects of traffic sounds were observed, which constantly increased with the increase in the sound level. The peak sound level was found to have a better performance than the equivalent sound level in the assessment of the psychological impact of traffic sounds. As for the physiological responses, significant effects of both the acoustic factors (sound type and sound level) and the non-acoustic factors (gender and exposure time) were observed. The relationship between sound level and physiological parameters varied among different sound groups. The variation in sound level hardly affected the participants’ HR and EDA when exposed to the conventional train and tram sounds. In contrast, HR and EDA were significantly affected by the levels of road traffic sound and high-speed train sound. Through a correlation analysis, a relatively weak correlation between the psychological evaluations and HR was found.

Impact of sound levels and patient-related factors on sleep of patients in the intensive care unit: a cross-sectional cohort study

Sleep disruption is common in patients in the intensive care unit (ICU). The aim of the study was to measure sound levels during sleep-protected time in the ICU, determine sources of sound, assess the impact of sound levels and patient-related factors on duration and quality of patients' sleep. The study was performed between 2018 and 2019. A commercially available smartphone application was used to measure ambient sound levels. Sleep duration was measured using the Patient's Sleep Behaviour Observational Tool. Sleep quality was assessed using the Richards-Campbell Sleep Questionnaire (RCSQ). The study population comprised 18 (58%) men and 13 (42%) women. There were numerous sources of sound. The median duration of sleep was 5 (IQR 3.5–5.7) hours. The median score on the RCSQ was 49 (IQR 28–71) out of 100 points. Sound levels were negatively correlated with sleep duration. The cut-off peak sound level, above which sleep duration was shorter than mean sleep duration in the cohort, was 57.9 dB. Simple smartphone applications can be useful to estimate sound levels in the ICU. There are numerous sources of sound in the ICU. Individual units should identify and eliminate their own sources of sound. Sources of sound producing peak sound levels above 57.9 dB may lead to shorter sleep and should be eliminated from the ICU environment. The sound levels had no effect on sleep quality.

Environmental aircraft noise aggravates oxidative DNA damage, granulocyte oxidative burst and nitrate resistance in Ogg1–/– mice

Background: Large epidemiological studies point towards a link between the incidence of arterial hypertension, ischaemic heart disease, metabolic disease and exposure to traffic noise, supporting the role of noise exposure as an independent cardiovascular risk factor. We characterised the underlying molecular mechanisms leading to noise-dependent adverse effects on the vasculature and myocardium in an animal model of aircraft noise exposure and identified oxidative stress and inflammation as central players in mediating vascular and cardiac dysfunction. Here, we studied the impact of noise-induced oxidative DNA damage on vascular function in DNA-repair deficient 8-oxoguanine glycosylase knockout (Ogg1–/–) mice.Methods and results: Noise exposure (peak sound levels of 85 and mean sound level of 72 dB(A) applied for 4d) caused oxidative DNA damage (8-oxoguanine) and enhanced NOX-2 expression in C57BL/6 mice with synergistic increases in Ogg1–/– mice (shown by immunohistochemistry). A similar pattern was found for oxidative burst of blood leukocytes and other markers of oxidative stress (4-hydroxynonenal, 3-nitrotyrosine) and inflammation (cyclooxygenase-2). We observed additive impairment of noise exposure and genetic Ogg1 deficiency on endothelium-independent relaxation (nitroglycerine), which may be due to exacerbated oxidative DNA damage leading to leukocyte activation and oxidative aldehyde dehydrogenase inhibition.Conclusions: The finding that chronic noise exposure causes oxidative DNA damage in mice is worrisome since these potential mutagenic lesions could contribute to cancer progression. Human field studies have to demonstrate whether oxidative DNA damage is also found in urban populations with high levels of noise exposure as recently shown for workers with high occupational noise exposure.

Environmental noise is a cardiovascular risk factor – mechanistic insights on oxidative stress, inflammatory pathways and endothelial dysfunction and preliminary data from diabetic mice.

Most traditional cardiovascular risk factors (diabetes, smoking or hyperlipidemia) are associated with vascular complications such as endothelial dysfunction, oxidative stress and inflammation. During the last two decades, large epidemiological studies have shown that the physical environment such as noise from road, aircraft or railway may facilitate the development of cardiovascular and metabolic diseases. These studies have demonstrated a link between the incidence of ischemic heart diseases or metabolic disease such as diabetes and exposure to noise, supporting its role as an independent cardiovascular risk factor (reviewed in the WHO Noise Guidelines for the European Region).We investigated the influence of aircraft noise exposure on molecular mechanisms identifying oxidative stress and inflammation as central players in mediating vascular dysfunction (Münzel et al. Eur. Heart J. 2017; Kröller‐Schön et al. Eur Heart J. 2018). Peak sound levels of 85 and mean sound level of 72 dB(A) applied for 1, 2 and 4 days caused an increase in systolic blood pressure, stress hormones and induced endothelial dysfunction, oxidative stress and inflammation. Control exposures to white noise for 4 days did not induce these changes.The potential additive effects of noise exposure and preexisting diabetes as well as the underlying molecular mechanisms are currently being investigated in a mouse model since the characteristics of noise induced vascular dysfunction considerably resemble the mechanisms of vascular dysfunction observed in diabetes.Support or Funding InformationOur experimental studies on noise effects in mice were supported by vascular biology research grants from the Foundation Heart of Mainz and the Boehringer Ingelheim Foundation for the collaborative research group „Novel and neglected cardiovascular risk factors: molecular mechanisms and therapeutic implications”.

Impact of intraoperative noise measurement on the surgeon stress and patient outcomes. A prospective, controlled, single-center clinical trial with 664 patients

BackgroundThe impact of sound-activated noise meters to decrease the noise level in the operating room is not clear. The aim of this study was to determine whether a sound-activated, visual noise meter would decrease noise levels, decrease postoperative morbidity, and improve surgeons’ feelings of well-being. MethodsThis prospective, single-center study proceeded in 2 phases. First, sound levels were compared during a 6-month period with noise measurement only and without a visual feedback function. Second, we conducted a subsequent 6-month phase with noise meters providing direct feedback. Surgeon disturbance during the operation was assessed by a questionnaire after each procedure. ResultsOf the 664 procedures included in this analysis, 447 (67.3%) were in phase 1 and 217 (32.7%) in phase 2. The noise levels in the operating room were decreased by 3.8 dB(A) from 54.6 ± 4.5 dB(A) in phase 1 to 50.8 ± 2.8 dB(A) in phase 2 after intervention with the feedback device (P < .001). During the procedures, there was an increase of 0.7 dB(A) (P < .001), with mean noise levels of 53.5 dB(A) at the beginning of the procedures and 54.2 dB(A) at the end. There was a correlation between the disturbance of the surgeon and the noise level (P < .001). ConclusionThe application of a visual noise warning device in an operating room decreased both the noise levels and surgeon stress and may offer sustained decreases in ambient and peak sound levels, potentially leading to improved quality outcomes in visceral surgery.

Evaluation of Noise Level at the Position of Water Cutter Operator at Selected Enterprise

Abstract The subject of this publication is to assess the exposure of the waterjet operator to the noise hazard. The publication presents basic information about noise in the work environment. Next, the procedure of noise measurement in the work environment was discussed and the results of tests carried out at the waterjet operator’s station for three basic activities were presented, ie: (1) plotter support, supervision of the cutting process, loading and receiving material, (2) auxiliary, transport and cleaning, (3) computer service, keeping documentation, hygienic and social break. The noise level test included the determination of: the maximum sound level A LA max, the peak sound level C LCpeak, the noise exposure level related to the 8-hour work day LEX,8h. Based on the obtained measurement results, it can be stated that the exposure to noise at the station of the waterjet operator is at an acceptable level.

Loudness–Duration Tradeoff in Ultrasonic Courtship Songs of Moths

Moths have evolved auditory channels under predation pressure from insectivorous bats that emit ultrasonic pulses for capturing prey, including moths. Tympanate moths perform evasive behavior in response to echolocation calls of bats, but they also utilize ultrasonic signals mostly generated by males close to an intended female mate in the context of courtship. Unlike calling songs used to advertise the presence and sexual attractiveness of the signaler, courtship songs need not always be acoustically conspicuous. Male courtship songs are predominantly soft but sufficient for detection by a nearby potential mate. Quiet courtship songs are thought to effectively avoid being eavesdropped by gleaning bats, acoustic parasitoids, and conspecific competitors, i.e., rival males. However, males of some moth species generate loud courtship songs. In the present study, the duration of courtship song, in addition to the sound level of the song was predicted to affect the likelihood of being perceived by eavesdroppers. Loud and lengthy courtship songs, which are easily exploited by eavesdroppers, would be expected to rarely evolve, because a female receiver close to a male emitting a conspicuous song would also be exposed to strong predation pressure. This study explored the relationship between the peak sound level and the duration of single song bouts in 26 moth species from the following families: Noctuidae, Erebidae, Crambidae, Pyralidae, and Geometridae. The softest and loudest songs with mean peak sound levels of 64 and 129dB peSPL had mean durations of 1900 and 312 ms, respectively, whereas the shortest and longest songs with mean durations of 110 and 8839 ms had mean peak sound levels of 102 and 74 dB peSPL, respectively. Thus, the peak sound level and duration of courtship song exhibited a significant negative relationship. Although the energetic cost of producing song and the size of the sound-producing organ might also affect the relationship, the data support the conclusion that acoustic moths have adaptively evolved ultrasonic courtship songs with properties between “soft-and-long” and “loud-and-short” to avoid eavesdroppers.

Children who say hand dryers 'hurt my ears' are correct: A real-world study examining the loudness of automated hand dryers in public places.

Previous research has suggested that hand dryers may operate at dangerously loud levels for adults. No research has explored whether they operate at a safe level for children's hearing. Children's ears are more sensitive to damage from loud sounds than adult ears. Health Canada prohibits the sale of toys with peak loudness greater than 100 dB. This study tested installed dryers in public washrooms to see if they were safe for children's hearing. Forty-four hand dryers in public washrooms were each measured for peak sound levels in a standardized fashion, including at children's ear canal heights. Each dryer was measured at 10 different combinations of heights and distances from the wall, and with and without hands in the air stream coming from the hand dryer, for a total of 20 measurements per dryer. Xlerator units performed the loudest, with all being louder than 100 dBA at all measurements whenever hands were in the airstream. Several Dyson Airblade models were also very loud, including the single loudest measurement of 121 dBA. While some other units operated at low sound levels, many units were louder at children's ear heights than at adult ear heights. Many dryers operated much louder than their manufacturers claimed, usually greater than 100 dBA (the maximum allowable noise level for products/toys meant for children). This study suggests that many hand dryers operate at levels far louder than their manufacturers claim and at levels that are clearly dangerous to children's hearing.