High Sound Levels Research Articles

Design, Development, and Testing of a New Device to Prevent High-Frequency Noise-Induced Damage: The “Dynamic Earplug”

Hearing loss resulting from prolonged exposure to loud noise is known as noise-induced hearing loss (NIHL), and it often affects professionals exposed to occupational sources of high sound levels. Among the professionals chronically exposed to noise, dentists use instrumentation that produces high-frequency noise. In this occupational category, NIHL is estimated to reach a 5% to 20% prevalence of workers. However, dentists and healthcare personnel have no suitable personal protection equipment designed for their needs. The study aims to develop a new individual hearing protection device called the “dynamic earplug”, which protects from high-frequency noise and amplifies speech frequencies. Testing with the Fonix 7000 Hearing Aid Test System showed effective filtering of high frequencies (above 4000 Hz) from dental instruments and a speech frequency amplification of up to 13 dB (500 Hz–1000 Hz). In a trial involving 20 subjects during an 8 h work shift, most participants positively evaluated the device’s esthetics, ease of insertion, comfort, stability, and noise attenuation while still being able to hear patients’ and colleagues’ voices. The dynamic earplug shows promise as an efficient and comfortable hearing protection solution for professionals exposed to high-frequency noise.

Investigating the influence of a bubble curtain on the underwater sound wave field generated by offshore pile driving.

Pile driving for offshore wind turbines typically generates high sound levels in the water column. Bubble curtains are frequently employed to protect marine fauna. This study aims to investigate the effect of a bubble curtain on the generated sound wave field. A recently developed seismo-acoustic model was extended by incorporating an established acoustic model of the bubble curtain. Subsequently, a detailed analysis of the sound wave field at an offshore wind farm construction site was conducted using both simulated and measured data. The results indicate a distance- and depth-dependent insertion loss, with reductions of approximately 2 to 4 dB observed at greater distances from the pile. For a more detailed analysis, a metric based on the concept of transmission loss was introduced. This demonstrates that the insertion loss caused by a bubble curtain can be formulated as a sum of two components: the loss due to the interaction between the bubbles and the sound wave field, and the altered bottom loss resulting from the scattering of the sound wave as it passes through the bubble curtain. Analysis of the simulation data highlights that sound scattering and the resulting altered bottom loss significantly contribute to the efficiency of the bubble curtain.

Low-side and multi-tone suppression in the base of the gerbil cochlea

The cochlea’s mechanical response to sound stimulation is nonlinear, likely due to saturation of the mechano-electric transduction current that is part of an electromechanical feedback loop. The ability of a second tone or tones to reduce the response to a probe tone is one manifestation of nonlinearity, termed suppression. Using optical coherence tomography to measure motion within the organ of Corti, regional motion variations have been observed. Here, we report on the suppression that occurs within the organ of Corti when a high sound level, low frequency suppressor tone was delivered along with a sweep of discreet single-tones. Responses were measured in the base of the gerbil cochlea at two best frequency locations, with two different directions of observation relative to the sensory tissue’s anatomical axes. Suppression extended over a wide frequency range in the outer hair cell region, whereas it was typically limited to the best frequency peak in the reticular lamina region and at the basilar membrane. Aspects of the observed suppression were consistent with the effect of a saturating nonlinearity. Recent measurements have noted the three-dimensional nature of organ of Corti motion. The effects of suppression observed here could be due to a combination of reduced motion amplitude and altered vibration axis.

Increased listening effort and decreased speech discrimination at high presentation sound levels in acoustic hearing listeners and cochlear implant users.

The sounds we experience in our everyday communication can vary greatly in terms of level and background noise depending on the environment. Paradoxically, increasing the sound intensity may lead to worsened speech understanding, especially in noise. This is known as the "Rollover" phenomenon. There have been limited studies on rollover and how it is experienced differentially across aging groups, for those with and without hearing loss, as well as cochlear implant (CI) users. There is also mounting evidence that listening effort plays an important role in challenging listening conditions and can be directly quantified with objective measures such as pupil dilation. We found that listening effort was modulated by sound level and that rollover occurred primarily in the presence of background noise. The effect on listening effort was exacerbated by age and hearing loss in acoustic listeners, with greatest effect in older listeners with hearing loss, while there was no effect in CI users. The age- and hearing-dependent effects of rollover highlight the potential negative impact of amplification to high sound levels and therefore has implications for effective treatment of age-related hearing loss.

Frequency dependence and harmonic distortion of stapes displacement and intracochlear pressure in response to very high level sounds

Previous reports have suggested that intracochlear pressures (PIC) measured at the base of the cochlea increase directly proportionally with stapes displacement (DStap) in response to moderately high (<130 dB SPL) level sounds. Consistent with this assumption, we have reported that for low frequency sounds (<1 kHz), stapes displacement and intracochlear pressures increase linearly with sound pressure level (SPL) for moderately high levels (<130 dB SPL), but saturate at higher exposure levels (>130 dB SPL). However, the magnitudes of each response were found to be frequency dependent, thus the relationship between DStap and PIC may vary at higher frequencies or higher levels.In order to further examine this frequency and level dependence, measurements of DStap and PIC were made in cadaveric human temporal bones prepared with a mastoidectomy and extended facial recess to expose the ossicular chain. PIC was measured in scala vestibuli (PSV) and scala tympani (PST) simultaneously with SPL in the external auditory canal (PEAC) and laser Doppler vibrometry (LDV) measurements of stapes velocity (VStap). Consistent with prior reports, DStap and PSV increased proportionally with sound pressure level in the ear canal up to a frequency-dependent saturation point, above which both DStap and PSV showed a distinct deviation from proportionality with PEAC, suggesting that their relationship may remain constant at these high frequencies. Likewise, while the asymptotic value, and SPL at which saturation occurred were frequency dependent in both DStap and PSV, the reduction in gain with increasing SPL above this level was constant above this level at all frequencies, and the magnitude of responses at harmonics of the driving frequency increased with increasing level, consistent with harmonic distortion via peak clipping. Importantly, this nonlinear distortion shifts the energy arriving at the inner ear to higher frequencies than are present in incident stimulus, thus exposing the high frequency sensitive components of the auditory system to more noise than would be expected from measurement of that stimulus on its own. Overall, responses suggest that the cochlear representation of very high-level air conducted stimuli is limited by nonlinearities in the middle ear, and that this peak limiting leads to increased high frequency cochlear exposures than are present in the driving stimulus.

Urbanisation and boating are the main contributors to underwater soundscapes in three temperate estuaries

Anthropogenic noise has been identified as one of the most harmful forms of global pollutants impacting both terrestrial and aquatic ecosystems. As global populations continue to increase, coastlines are seeing substantial increases in the level of urbanisation. Although measures are in place to minimise stress on fauna, they rarely consider the impact of anthropogenic noise. In Australia, New South Wales (NSW) estuaries have seen extensive increases in urbanisation in recent years. Yet, there remains minimal baseline data on their soundscapes to determine if noise pollution is a threat. This research provides a first assessment of baseline sounds across a temporal and seasonal scale. Recreational boating was the primary soundscape contributor in estuaries, and estuaries with higher urbanisation levels contained higher sound levels. This research provides useful information for managers of NSW estuaries and is of global relevance in an era of increasing generation of anthropogenic noise in estuarine and coastal systems.

Noise-Induced Hearing Loss Awareness and Prevention: A Cross-Sectional Study Among the Population of the Southern Region of Saudi Arabia.

Noise-induced hearing loss (NIHL) is a prevalent and preventable health issue globally. This study aims to evaluate the symptoms, knowledge, beliefs, and preventive practices regarding NIHL among the general population of the southern region of Saudi Arabia. A cross-sectional study was conducted from May to July 2024, using a self-administered, validated electronic questionnaire distributed in Arabic via social media platforms. The questionnaire assessed socio-demographic data, NIHL awareness, attitudes towardprevention, and personal practices regarding noise exposure. The sample included 400 participantsanalyzed using SPSS version 23 (IBM Corp., Armonk, NY), with associations measured through the chi-square and Fisher's exact tests. Most participants were Saudi nationals (97%) and females (81.3%). Symptoms of NIHL, such as tinnitus and the need to increase TV or radio volume, were prevalent among participants. Most participants (88.5%) were aware that high sound levels affect hearing, yet only 9.5% correctly identified the minimum duration of exposure that could harm hearing. Social media was the primary source of information (51.3%). Positive preventive practices were noted, with 66% lowering device volumes and 55.3% recommending sound restrictions on tablets. Significant associations were found between better preventive practices and higher income as well as marital status. The study highlights the high basic awareness of NIHL but identifies critical knowledge gaps regarding the minimum sound level and duration that affect hearing negatively. Enhanced public health education and technological interventions are needed to improve prevention practices. Future research should include longitudinal studies and diverse populations to better understand and address NIHL.

Manikin study showed that neonates are exposed to high sound and vibration levels during helicopter incubator transports.

This initial Norwegian study aimed to quantify the vibrations and sounds experienced by neonates when they were transported by helicopter in an incubator. Two neonatal manikins weighing 500 and 2000 g were placed in a transport incubator and transported in an Airbus H145 D3 helicopter during standard flight profiles. The vibrations were measured on the mattress inside the incubator and the sound levels were measured inside and outside the incubator. The highest vibration levels were recorded during standard flight profiles when the lighter manikin was used. These ranged 0.27-0.94 m/s2, compared to 0.27-0.76 m/s2 for the heavier manikin. The measurements exceeded the action levels set by the European Union Vibration Directive for adult work environments. The sound levels inside the incubator ranged 84.6-86.3 A-weighted decibels, with a C-weighted peak level of 122 decibels. The sound levels inside the incubator were approximately 10 decibels lower than outside, but amplification was observed in the incubator at frequencies below 160 Hz. Vibrations were highest for the lighter manikin. The sound levels during helicopter transport were higher than recommended for neonatal environments and sounds were amplified within the incubator at lower frequencies.

Examining the intersection of carceral space and well‐being: Correctional officers' perspectives on old and new prison design

AbstractIn the current study, we explored the prison design and infrastructural changes that Canadian correctional officers consider to be essential in the construction of a new provincial correctional institution intended to replace Her Majesty's Penitentiary (HMP) in the Canadian province of Newfoundland and Labrador. Analyzing 28 semi‐structured interviews conducted with correctional officers employed at HMP, we found the poor working conditions within HMP are, at least in part, related to the physical design of the prison, including inadequate lighting, poor air quality and temperature, high sound levels, and other spatial limitations. Building on the prison design literature, findings suggest that while prison design requires attention to physical security at the forefront, there are ways to improve the space, recognizing how an uncomfortable workplace and living conditions also pose a potential threat to the well‐being and safety of correctional officers and people who are incarcerated.

Device and Fitting Protocol for a Transitional Intervention for Debilitating Hyperacusis.

This report describes a hearing device and corresponding fitting protocol designed for use in a transitional intervention for debilitating loudness-based hyperacusis. The intervention goal is to transition patients with hyperacusis from their typical counterproductive sound avoidance behaviors (i.e., sound attenuation and limited exposure to healthy low-level sounds) into beneficial sound therapy treatment that can expand their dynamic range to the point where they can tolerate everyday sounds and experience an improved quality of life. This requires a combination of counseling and sound therapy, the latter of which is provided via the hearing device technology, signal processing, and precision fitting approach described in this report. The device combines a miniature behind-the-ear sound processor and a custom earpiece designed to maximize the attenuation of external sounds. Output-limiting loudness suppression is used to restrict exposure to offending high-level sounds while unity gain amplification maximizes exposure to healthy and tolerable lower level sounds. The fitting process includes measurement of the real-ear unaided response, the real-ear measurement (REM) system noise floor, the real-ear occluded response, real-ear insertion gain, and the output limit. With these measurements, the device can achieve the prescribed unity gain needed to provide transparent access to comfortable sound levels. It also supports individualized configuration of the therapeutic noise from an on-board sound generator and adaptive output limiting based on treatment-induced increases in dynamic range. The utility of this device and fitting protocol, in combination with structured counseling, is highlighted in the outcomes of a successful 6-month trial of the transitional intervention described in a companion report in this issue.

The Impact of the Fluid-Solid Coupling Behavior of Macro and Microstructures in the Spiral Cochlea on Hearing.

The cilia of the outer hair cells (OHCs) are the key microstructures involved in cochlear acoustic function, and their interactions with lymph in the cochlea involve complex, highly nonlinear, coupled motion and energy conversions, including macroscopic fluid-solid coupling. Recent optical measurements have shown that the frequency selectivity of the cochlea at high sound levels is entirely mechanical and is determined by the interactions of the hair bundles with the surrounding fluid. In this paper, an analytical mathematical model of the spiral cochlea containing macro- and micromeasurements was developed to investigate how the phonosensitive function of OHCs' motions is influenced by the macrostructural and microstructural fluid-solid coupling in the spiral cochlea. The results showed that the macrostructural and microstructural fluid-solid coupling exerted the radial forces of OHCs through the flow field, deflecting the cilia and generating frequency-selective properties of the microstructures. This finding showed that microstructural frequency selectivity arises from the radial motions of stereocilia hair bundles and enhances the hearing of sound signals at specific frequencies. It also implied that the macrostructural and microstructural fluid-solid couplings influence the OHCs' radial forces and that this is a key factor in the excitation of ion channels that enables their activity in helping the brain to detect sound.

Determination of the sound level during different management measures in piglet rearing related to animal welfare and human health and safety

In the present study, sound level measurements were taken during management measures with expected high noise exposure on three German pig farms in order to quantify the noise level for pigs and farm staff. The sound level was measured during different activities, such as teeth grinding and tail docking of piglets, vaccination, castration with anaesthesia, stabling and rehousing the pigs. The equivalent continuous sound level (LAeq) was measured as well as the actual sound level (LAF) and the peak sound pressure level (LCPKmax). The latter two were assigned to specific sound events during the individual measures, such as piglet screams or using the pig paddle. Rehousing the pigs at the end of the nursery period resulted in the highest continuous sound levels (LAeq= 83.3 ± 4.9 dB(A)), followed by anaesthesia before castration (LAeq = 78.1 ± 7.4 dB(A)) and teeth grinding and tail docking of piglets (LAeq = 77.5 ± 3.6 dB(A)). The peak sound pressure level LCPKmax was more than 100 dB(A) for all measures with an absolute maximum of 129.7 dB(A) when pigs were being moved out of the nursery compartment. Furthermore, the human pain threshold of 120 dB(A) was exceeded in isolated cases when nursery pigs were being moved to the stable (LCPKmax = 121 dB(A)) and during anaesthesia before castration (LCPKmax = 125.2 dB(A)). During the individual measures, particularly high sound levels were generated when using a pig paddle (LAF = 92.1 ± 7.8 dBA)), when pigs ran over a loading ramp of a transporter (LAF = 93.8 ± 1.4 dB(A)) or when piglets screamed (LAF = 87.9 ± 7.5 dB(A)). The piglets’ screams were particularly loud during anaesthesia before castration (LAF = 90.0 ± 9.2 dB(A)), during vaccination (LAF = 89.6 ± 6.5 dB(A)) and during teeth grinding and tail docking (LAF = 89.5 ± 5.9 dB(A)).Even if the LAeq was always below 85 dB(A), i. e. the limit specified in European legislation (EU Directive 2008/120/EC) for continuous noise in piggeries, there were brief sound peaks that exceeded the pain threshold of 120 dB(A). In the interest of animal welfare and human health, noise should be reduced by a gentle handling of pigs. The use of the pig paddle should be restricted whenever possible. Additionally, farm staff should wear hearing protection when carrying out those measures that were identified as particularly noise-intensive in this study.

In-situ comparison of high-order detonations and low-order deflagration methodologies for underwater unexploded ordnance (UXO) disposal

The unexploded ordnance (UXO) on the seabed off Northwest Europe poses a hazard to offshore developments such as windfarms. The traditional removal method is through high-order detonation of a donor explosive charge placed adjacent to the UXO, which poses a risk of injury or death to marine mammals and other fauna from the high sound levels produced and is destructive to the seabed. This paper describes a sea-trial in the Danish Great Belt to compare the sound produced by high-order detonations with that produced by deflagration, a low-order disposal method that offers reduced environmental impact from noise. The results demonstrate a substantial reduction over high-order detonation, with the peak sound pressure level and sound exposure level being around 20 dB lower for the deflagration. The damage to the seabed was also considerably reduced for deflagration, although there was some evidence for residues of explosives related chemicals in sediments.

A silent echo-planar spectroscopic imaging readout with high spectral bandwidth MRSI using an ultrasonic gradient axis.

We present a novel silent echo-planar spectroscopic imaging (EPSI) readout, which uses an ultrasonic gradient insert to accelerate MRSI while producing a high spectral bandwidth (20 kHz) and a low sound level. The ultrasonic gradient insert consisted of a single-axis (z-direction) plug-and-play gradient coil, powered by an audio amplifier, and produced 40 mT/m at 20 kHz. The silent EPSI readout was implemented in a phase-encoded MRSI acquisition. Here, the additional spatial encoding provided by this silent EPSI readout was used to reduce the number of phase-encoding steps. Spectroscopic acquisitions using phase-encoded MRSI, a conventional EPSI-readout, and the silent EPSI readout were performed on a phantom containing metabolites with resonance frequencies in the ppm range of brain metabolites (0-4 ppm). These acquisitions were used to determine sound levels, showcase the high spectral bandwidth of the silent EPSI readout, and determine the SNR efficiency and the scan efficiency. The silent EPSI readout featured a 19-dB lower sound level than a conventional EPSI readout while featuring a high spectral bandwidth of 20 kHz without spectral ghosting artifacts. Compared with phase-encoded MRSI, the silent EPSI readout provided a 4.5-fold reduction in scan time. In addition, the scan efficiency of the silent EPSI readout was higher (82.5% vs. 51.5%) than the conventional EPSI readout. We have for the first time demonstrated a silent spectroscopic imaging readout with a high spectral bandwidth and low sound level. This sound reduction provided by the silent readout is expected to have applications in sound-sensitive patient groups, whereas the high spectral bandwidth could benefit ultrahigh-field MR systems.

A Guinea Pig Model Suggests That Objective Assessment of Acoustic Hearing Preservation in Human Ears With Cochlear Implants Is Confounded by Shifts in the Spatial Origin of Acoustically Evoked Potential Measurements Along the Cochlear Length.

Our recent empirical findings have shown that the auditory nerve compound action potential (CAP) evoked by a low-level tone burst originates from a narrow cochlear region tuned to the tone burst frequency. At moderate to high sound levels, the origins shift to the most sensitive audiometric regions rather than the extended high-frequency regions of the cochlear base. This means that measurements evoked from extended high-frequency sound stimuli can shift toward the apex with increasing level. Here we translate this study to understand the spatial origin of acoustically evoked responses from ears that receive cochlear implants, an emerging area of research and clinical practice that is not completely understood. An essential step is to first understand the influence of the cochlear implant in otherwise naive ears. Our objective was to understand how function of the high-frequency cochlear base, which can be excited by the intense low-frequency sounds that are frequently used for objective intra- and postoperative monitoring, can be influenced by the presence of the cochlear implant. We acoustically evoked responses and made measurements with an electrode placed near the guinea pig round window. The cochlear implant was not utilized for either electrical stimulation or recording purposes. With the cochlear implant in situ, CAPs were acoustically evoked from 2 to 16 kHz tone bursts of various levels while utilizing the slow perfusion of a kainic acid solution from the cochlear apex to the cochlear aqueduct in the base, which sequentially reduced neural responses from finely spaced cochlear frequency regions. This cochlear perfusion technique reveals the spatial origin of evoked potential measurements and provides insight on what influence the presence of an implant has on acoustical hearing. Threshold measurements at 3 to 11 kHz were elevated by implantation. In an individual ear, thresholds were elevated and lowered as cochlear implant was respectively inserted and removed, indicative of "conductive hearing loss" induced by the implant. The maximum threshold elevation occurred at most sensitive region of the naive guinea pig ear (33.66 dB at 8 kHz), making 11 kHz the most sensitive region to acoustic sounds for guinea pig ears with cochlear implants. Conversely, the acute implantation did not affect the low-frequency, 500 Hz thresholds and suprathreshold function, as shown by the auditory nerve overlapped waveform. As the sound pressure level of the tone bursts increased, mean data show that the spatial origin of CAPs along the cochlear length shifted toward the most sensitive cochlear region of implanted ears, not the extended high-frequency cochlear regions. However, data from individual ears showed that after implantation, measurements from moderate to high sound pressure levels originate in places that are unique to each ear. Alterations to function of the cochlear base from the in situ cochlear implant may influence objective measurements of implanted ears that are frequently made with intense low-frequency sound stimuli. Our results from guinea pigs advance the interpretation of measurements used to understand how and when residual acoustic hearing is lost in human ears receiving a cochlear implant.

The Merits of Bilateral Application of Middle Ear Implants in Patients With Bilateral Conductive and/or Mixed Hearing Loss.

This study investigated sound localization abilities in patients with bilateral conductive and/or mixed hearing loss (BCHL) when listening with either one or two middle ear implants (MEIs). Sound localization was measured by asking patients to point as quickly and accurately as possible with a head-mounted LED in the perceived sound direction. Loudspeakers, positioned around the listener within a range of +73°/-73° in the horizontal plane, were not visible to the patients. Broadband (500 Hz-20 kHz) noise bursts (150 ms), roved over a 20-dB range in 10 dB steps was presented. MEIs stimulate the ipsilateral cochlea only and therefore the localization response was not affected by crosstalk. Sound localization was better with bilateral MEIs compared with the unilateral left and unilateral right conditions. Good sound localization performance was found in the bilaterally aided hearing condition in four patients. In two patients, localization abilities equaled normal hearing performance. Interestingly, in the unaided condition, when both devices were turned off, subjects could still localize the stimuli presented at the highest sound level. Comparison with data of patients implanted bilaterally with bone-conduction devices, demonstrated that localization abilities with MEIs were superior. The measurements demonstrate that patients with BCHL, using remnant binaural cues in the unaided condition, are able to process binaural cues when listening with bilateral MEIs. We conclude that implantation with two MEIs, each stimulating only the ipsilateral cochlea, without crosstalk to the contralateral cochlea, can result in good sound localization abilities, and that this topic needs further investigation.

Experimental study on the effect of visual information of source image to evaluate the annoyance of aircraft noise

Laboratory tests in anechoic chambers are effective for evaluating environmental noise. In the actual environment, it is said that human reactions are greatly influenced not only by a sense of hearing but also by various senses, especially visual sensation. In this study, we experimentally evaluated the annoyance of environmental noise using an audio-visual simulation system that combines a three-dimensional sound field system in an anechoic room and a video playback system equipped with a dome-shaped screen. Previous studies have shown that the annoyance of traffic noise changes depending on the image presented, but aircraft noise is less affected by visual effects than other traffic noises. Therefore, in this study, we focused on aircraft noise and made experimental investigations. We considered two reasons why the annoyance evaluation of aircraft noise seems to be less affected by vision: the small size of the visible image, and the high sound power level relative to the image. Accordingly, we experimentally evaluated the difference in perception of annoyance due to changes in the image size by presenting images of artificially changed sizes of aircraft images as stimuli.

Risk Assessment of Noise Pollution in a Cement Plant: Perspectives and Recommendations

Introduction: noise is an acoustic phenomenon producing an auditory sensation considered unpleasant or annoying.Exposure to high sound levels over 85 dB(A) can affect the auditory system and other extra-auditory systems Our study had the general objective of evaluating the impact of noise related to noise exposure in the Lafarge Holcim Guinea factory. Material and methods: This was a prospective descriptive study lasting 6 months from March 01, 2022 to September 01, 2022. It focused on the 150 workers at the Lafarge Holcim Guinea plant and their work areas. Results: during our study, we recorded 131 workers who met our selection criteria. Our study population was young with an average age of 40.7 years with extremes of 26-53 years. About the measurement 3 areas out of 10 had a noise level above 85 dB(A). The most frequent signs felt during or after work were whistling/buzzing with 55%. Only 48.1% regularly used this PPE and caps were the most used PPE. Conclusion: at the end of this study, it appears that the workers are mainly exposed to noise and have hearing problems. Despite the availability of PPE, many workers do not use it; however, better communication on the risks associated with noise pollution and the establishment of regular supervision of the correct wearing of PPE would improve the protection and safety of workers.

A practical method for assessing and managing the risk of noise induced hearing loss for divers in high-noise underwater environments

The purpose of this study was to develop a method to assessing and managing the risk of noise induced hearing loss (NIHL) to commercial divers operating within or nearby sites with high underwater sound levels. Our method involves using a transfer function to convert underwater sound levels to airborne sound levels at the diver’s ear inside a helmet, which can then be assessed against the 85 dB LAeq (8 hour) exposure limit for NIHL. We measured this transfer function for a standard commercial diving helmet (Kirby Morgan 37) during nearby impact piling using a Soundtrap hydrophone in the water and Brüel and Kjær sound level meter with a type-1 microphone at the ear position. We then used the results to calculate a time limit for a diver to be in the water before the in-ear sound levels exceed the NIHL exposure limit.

Soundscapes of Urban Parks in Cities with Populations of Over 100,000 in the Silesian Voivodeship

The article presents the results of soundscape assessments conducted in urban parks in the Silesian Voivodeship. The Silesian Voivodeship is characterised by a high degree of industrialisation and the greatest population density in Poland. The studies were conducted in the urban parks of all the cities in the voivodeship with populations of over 100,000 citizens. This selection was determined based on acoustic maps that are prepared for cities with populations of over 100,000 citizens as required by law, and on the fact that the role of urban parks is frequently marginalised in the context of city life. The goal of the studies was to define an objective acoustic appeal assessment method for urban parks in city centres. Measurements were carried out in 34 parks located in the centres of 12 cities. A-weighted sound levels LAeq were determined for 107 measuring points in urban parks and the streets adjacent to them. Differences in the A-weighted sound levels LAeq were presented for each studied park and the adjacent streets. Minimum and maximum sound values were subsequently determined for each measuring point. Significant differences in the minimum and maximum sound values in given locations were found despite minor differences in LAeq values. It was also discovered that though parks may often exhibit high A-weighted sound levels LAeq, there are other factors that influence the appeal of park soundscapes.