Decibel Levels Research Articles

Effect of Classical Counterconditioning (Quiet Kennel Exercise) on Barking in Sheltered Dogs

A major welfare concern in animal shelters is excessive barking from kenneled dogs. This contributes to noise pollution, can cause hearing damage in both dogs and humans, and has a negative effect on all animals housed within earshot. Excessive barking is often driven by fear and frustration, negative emotional states often difficult to alter in the shelter setting. This study demonstrated implementation of a simple classical counterconditioning measure, the Quiet Kennel Exercise (QKE) in adoption wards at an open admission shelter improved the emotional state of dogs, reduced fear, frustration and excessive barking.Baseline data were collected over two weeks using a hand-held decibel meter to measure the volume of barking in each ward three times daily. Mounted cameras were used to document the number of people passing through each ward each day. Data were collected for 18 days of intervention over four weeks. During this time, signs were placed to encourage people to toss treats to each dog, and treats were provided in buckets. Decibel levels were measured three times daily and the numbers of people who did and did not toss treats were recorded to measure compliance.There was an increase in compliance and a decrease in maximum decibel readings over the course of the intervention. For each one percent increase in compliance, there was an average decrease of 17.3 dB in the maximum volume in decibels. Therefore, increasing participation in the QKE can significantly decrease barking volume. This easily implemented intervention has the potential to decrease noise levels and improve welfare for both humans and dogs in kennel settings.

Decibel level of coughing as a predictor of extubation outcome in mechanically ventilated intensive care patients: A prospective, observational study

AimThis study aims to evaluate the feasibility and clinical utility of measuring cough decibel level as predictive markers for extubation outcomes in mechanically ventilated patients. DesignA prospective observational study. SettingThree interdisciplinary medical-surgical intensive care units across China. Main outcome measuresThe primary outcomes assessed were extubation results in patients. Secondary measures included the cough decibel level, semiquantitative cough intensity scores, and white card test results recorded prior to extubation. ResultsA total of 71 patients were included, 55 patients were in the extubation success group and 16 in the failure group. The mean age was 78(71,83) years, mainly male (73.2 %). Despite the baseline characteristics being mostly consistent across both groups, significant differences were noted in duration of mechanical ventilation, and intensive care units and hospital stay. Remarkably, the cough decibel was substantially lower in the extubation failure group compared to the other group (78.69 ± 8.23 vs 92.28 ± 7.01 dB). The Receiver Operating Characteristic curve analysis revealed that a cough decibel below 85.77 dB is the optimal threshold for predicting extubation failure, exhibiting an 80 % sensitivity and 91.67 % specificity. ConclusionThe study corroborates that the cough decibel level serves as a quantifiable metric in patients undergoing mechanical ventilation. It posits that the likelihood of extubation failure escalates when the cough decibel falls below 85.77 dB. Implications for clinical practiceQuantification of coughing capacity in decibels may be a good predictor of extubation outcome, thus offering assistance to healthcare professionals in evaluating the readiness of patients for extubation.

Surgeons Who Perform Total Hip Arthroplasty Are at Risk for Noise-Induced Hearing Loss, Especially When Using Automated Broaching.

Noise-induced hearing loss (NIHL) is a serious concern for orthopedic surgeons. The National Institute for Occupational Safety and Health (NIOSH) sets the safe exposure limit at 85 dB for 8 hours, yet operating rooms often surpass this limit. This study investigated if using an automated broaching system exposes orthopedic surgeons to dangerous decibel (dB) levels. A prospective study analyzed 138 intraoperative sound recordings from 92 total hip arthroplasty (THA) surgeries and 46 baseline measurements at an academic-affiliated private practice, using the NIOSH Sound Level Meter (SLM) application and a microphone. The surgeries were categorized into manual and automated broaching. Key metrics measured included maximal dB level (MDL), peak sound pressure (LCpeak), average continuous sound (LAeq), and average weighted sound in an 8-hour period (TWA), along with dose representations, to identify hazardous noise levels. Of the 92 THA sound recordings, 50 used manual broaching and 42 employed automated broaching. Automated broaching exhibited higher noise levels, with an average MDL of 109.92 dBA, a LAeq of 86.09 dBA, a TWA of 76.48 dBA, and a projected noise dose of 137.74%. In contrast, manual broaching exhibited an average MDL of 105.87 dBA, a LAeq of 83.06 dBA, a TWA of 72.82 dBA, and a projected noise dose of 82.02%. This study highlights the auditory risks from automated broach and manual THA surgeries that orthopedic surgeons experience. Manufacturers should focus on reducing instrument noise when designing surgical tools and orthopedic surgeons and operating room staff should take measures to protect themselves from NIHL during surgery. [Orthopedics. 202x;4x(x):xx-xx.].

The impact of different types and levels of construction noise on physiological responses: Focusing on standardization and habituation

Construction noise is a pervasive and influential source of stress for urban residents and can lead to various health problems, including hormonal dysfunction and cardiovascular diseases. Despite considerable research on the general impact of urban noise, studies that specifically address physiological responses to construction noise are limited. This study explores the relationship between different types of construction noise (tonal and impulsive) and physiological responses, focusing on electrodermal activity (EDA) at varying decibel levels (40, 60, and 80 dBA). The experimental results demonstrated that the z-score standardization method excels in EDA analysis in response to construction noise, particularly showing that noise levels significantly affect the phasic EDA of subjects exposed to tonal noise. Additionally, it was found that EDA responses recorded during the initial 30 s decisively influenced the subjective rating of annoyance. These results highlight the importance of considering both noise type and exposure duration in managing construction noise to mitigate its negative impacts on urban residents. This study can provide practical implications for urban planning, potentially minimizing complaints from urban residents and the impact of construction noise on communities.

Clinical impact of hyperbaric oxygen therapy combined with steroid treatment for sudden sensorineural hearing loss: A case-control study.

The aim of present study was to evaluate the clinical efficacy of hyperbaric oxygen therapy (HBOT) as a primary therapy combined with standard systemic corticosteroid treatment for sudden sensorineural hearing loss (SSNHL) compared to treatment without the use of HBOT (non-HBOT) through clinical data and advanced analytical approaches. Case-control study. Conducted across three Japanese medical centers involving 298 SSNHL patients diagnosed between 2020 and 2023. Inclusion criteria encompassed first onset and treatment, WHO grade 3 or 4 initial hearing impairment, receipt of systemic corticosteroid therapy within 14 days of symptom onset, and initiation of HBOT within the same timeframe for the case group. The primary outcome measure was the difference in hearing improvement (mean hearing level in decibels, dB) between the two groups, assessed by pure-tone audiometry at baseline and 3 months post-treatment, using the inverse probability of treatment weighting (IPTW) method adjusted for covariate differences. The study included 67 patients in the HBOT group and 68 in the non-HBOT group. The HBOT group exhibited significantly greater hearing improvement (IPTW-adjusted difference: 7.6 dB, 95% CI 0.4-14.7; p = 0.038). Patients without vertigo in the HBOT group demonstrated substantial hearing improvement (11.5 dB, 95% CI 2.3-20.6; p = 0.014), whereas those with vertigo showed no significant improvement (-1.8 dB, 95% CI -11.8-8.3; p = 0.729). The HBOT group also had a significantly higher association with complete recovery (IPTW-adjusted odds ratio: 2.57, 95% CI 1.13-5.85; p = 0.025). In SSHNL, HBOT combination therapy yielded slightly but significantly improved hearing outcomes compared to non-HBOT treatment. 4.

Chinese Emotional Speech Audiometry Project (CESAP): Establishment and Validation of a New Material Set With Emotionally Neutral Disyllabic Words.

The Chinese Emotional Speech Audiometry Project (CESAP) aims to establish a new material set for Chinese speech audiometry tests, which can be used in both neutral and emotional prosody settings. As the first endeavor of CESAP, this study demonstrates the development of the material foundation and reports its validation in neutral prosody. In the development step, 40 phonetically balanced word lists consisting of 30 Chinese disyllabic words with neutral valence were first generated. In a following affective rating experiment, 35 word lists were qualified for validation based on the familiarity and valence ratings from 30 normal-hearing (NH) participants. For validation, performance-intensity functions of each word list were fitted with responses from 60 NH subjects under six presentation levels (-1, 3, 5, 7, 11, and 20 dB HL). The final material set was determined by the intelligibility scores at each decibel level and the mean slopes. First, 35 lists satisfied the criteria of phonetic balance, limited repetitions, high familiarity, and neutral valence and were selected for validation. Second, 15 lists were compiled in the final material set based on the pairwise differences in intelligibility scores and the fitted 20%-80% slopes. The established material set had high reliability and validity and was sensitive to detect intelligibility changes (50% slope: 6.20%/dB; 20%-80% slope: 5.45%/dB), with small covariance of variation for thresholds (15%), 50% slope (12%), and 20%-80% slope (12%). Our final material set of 15 word lists takes the initiative to control the emotional aspect of audiometry tests, which enriches available Mandarin speech recognition materials and warrants future assessments in emotional prosody among populations with hearing impairments. https://doi.org/10.23641/asha.25742814.

Fusedly Deposited Frequency-Selective Composites Fabricated by a Dual-Nozzle 3D Printing as Microwave Filter.

We report a fusedly deposited frequency-selective composite (FD-FSCs), fabricated with a dual-nozzle 3D printer using a conductive carbon black (CB) polylactic acid (PLA) composite filament and a pure PLA polymer filament. The square frequency-selective pattern was constructed by the conductive CB/PLA nanocomposite, and the apertures of the pattern were filled with the pure dielectric PLA material, which allows the FD-FSC to maintain one single plane, even under bending, and also affects the resonating frequency due to the characteristic impedance of PLA (εr' ≈ 2.0). The number of the deposition layer and the printing direction were observed to affect electrical conductivity, complex permittivity, and the frequency selectivity of the FD-FSCs. In addition, the FD-FSCs designed for an X-band showed partial transmission around the resonant frequency and was observed to, quite uniformly, transmit microwaves in the decibel level of -2.17~-2.83 dB in the whole X-band, unlike a metallic frequency selective surface with full transmission at the resonance frequency. FD-FSCs embedded radar absorbing structure (RAS) demonstrates an excellent microwave absorption and a wide effective bandwidth. At a thickness of 4.3 mm, the 10 dB bandwidth covered the entire X-band (8.2~12.4 GHz) range of 4.2 GHz. Therefore, the proposed FD-FSCs fabricated by dual-nozzle 3D printing can be an impedance modifier to expand the design space and the application of radar absorbing materials and structures.

Survey of background noise levels inside classrooms on a college campus

Sound level measurements were made for 18 classrooms and learning spaces on the Marietta Campus of Kennesaw State University, Georgia, USA. Excessive background noise in learning spaces diminishes the speech intelligibility from the speaker to the listeners. The noise measured was in empty or nearly empty classrooms with no one talking. The primary background noise source was observed to be due to heating, ventilation, and air-conditioning equipment. The results are compared with a student survey to see if the noise complaints correlate with the noisiest classrooms in terms of their average A-weighted decibel levels. In addition, conformance with ANSI-ASA S12.60-2010/Part 1 (Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools) is evaluated.

Aircraft-Produced Sonic Booms and Marine Life

With the advent of new-age supersonic aircraft such as NASA’s X-59, Boom Supersonic’s Overture, and Spike Aerospace’s S-512, there is an emergent need to investigate their environmental consequences. This review evaluates existing research and information to determine what is currently known about supersonic aircraft and their potential impacts on marine life through a three-step process. 1) Determining possible characteristics of sonic booms produced by the aircraft: the aircraft being evaluated in this article produce low-frequency (0.1-100 Hz) sounds with surface PLdBs (perceived surface loudness decibel levels) around 70-75 dB. 2) Assessing the behavior of similar sounds as they interact with the ocean: sonic booms have been observed to penetrate the ocean for 98-164 ft, but this depth can vary due to differences between the experimental and real-life flight conditions. A separate effect, produced by sonic booms’ contact with the ocean surface, may penetrate deeper as infrasound. 3) Evaluating the potential consequences of these sounds on marine life: the continuous production of sonic booms along flight paths worldwide raises concerns about possible noise pollution, adding to the existing issue of oceanic anthropogenic noise pollution. Existing literature on underwater noise pollution—with similar frequencies and comparable intensities—shows negative impacts on marine reproduction, communication, stress levels, and physical health. This review contributes to broader ongoing discussions surrounding the resurgence of supersonic aviation and its environmental impact. Further research is necessary to assess the impact that transoceanic supersonic flight could have on marine ecosystems to truly determine supersonic flight’s environmental footprint.

THE CREATION OF NOISE LEVEL ALERT DEVICE WITH THE USE OF SOUND SENSOR

Noise pollution, accelerated by modernization and urbanization, requires noise monitoring to protect human health and productivity levels. This study utilized a quantitative approach and experimental design to collect data on the device’s processing time, feedback speed, and distance parameters. This study focused on three decibel levels: 60 decibels, 80 decibels, and 100 decibels. The results proved that the Noise Level Alert Device is efficient, with its processing times averaging 0.23, 0.21, and 0.18 seconds, respectively. Feedback speeds were similarly swift, averaging 0.86, 0.15, and 0.12 seconds, respectively. Furthermore, the Noise Level Alert Device detected noise up to 60 centimeters for 60 decibels, and up to 1.5 meters for 80 and 100 decibels. The sound sensor was used to create an accurate Noise Level Alert Device. The device gives a voice alert whenever the noise exceeds the predetermined decibel while being an affordable Noise Level Alert Device. Based on the results, the Noise Level Alert Device can quickly process noise and give feedback with accuracy. Lastly, as it was capable of detecting noise from different distances, the device can be further improved by using a higher-grade sound sensor to have a smoother process in detecting sound waves and to be able to cover bigger spaces.

An updated job-exposure matrix for occupational noise: development and validation.

The aim of this study was to create a quantitative job-exposure matrix (JEM) for noise including a large set of measurements for the Swedish workforce, a detailed exposure-level assessment, spanning over an extensive time period from 1970 to 2014. The JEM was developed by 2 teams, each with an experienced occupational hygienist and an occupational safety engineer. Each pair assessed the exposure using measurements performed and reported by occupational hygienists, occupational safety engineers, or similar, from 1970 to 2014. The measurements included either the original LAeq(8h) measurements or an LAeq(8h) levels calculated from partial measurements of the working day, provided that the measurement targeted a regular task usually performed during a full workday. The collection of measurement reports was done in 2008 and 2012 by contacting clinics working in the area of occupational health or occupational safety engineers and their submitted reports were added to our own material. Noise exposure assessments were inserted at the appropriate time period for the relevant job family. The final matrix was developed in a consensus procedure and the validity was investigated by comparison of the 2 team's individual results. The noise JEM contains 321 job families with information regarding occupational noise from 1970 to 2014. The time-period label has a 5-yr scale starting in 1970. The estimated average 8 h (TWA) noise level in decibels [dB(A)] for every job family and 5-yr period was coded as 1: <70 dB(A), 2: 70 to 74 dB(A), 3: 75 to 79 dB(A), 4: 80 to 84 dB(A) or 5: 85(+) dB(A). The validation showed no systematic difference in relative position and very high agreement in the ordering of paired ordinal classifications. The JEM has also successfully been applied in several epidemiological studies. We present a JEM for occupational noise using Swedish data from 1970 to 2014 with a higher degree of sensitivity in assessed noise exposure compared with the previously existing version. Repeated application of the JEM, in epidemiological studies, has shown consistent results and contributed to yielding important findings.

Risk of noise-induced hearing loss in the spine surgeon

Occupation-related noise-induced hearing loss (NIHL) has both negative economic and quality of life implications. The risk spine surgeons undertake in regards to NIHL during operative intervention is unknown. Governing bodies, including the National Institute for Occupational Safety and Health, have recommended exposure limits not to exceed 85 decibels (dB) over 8 hours. The purpose of this study is to characterize noise exposure to spine surgeons in the operating room (OR). Prospective collection of intraoperative recordings of spinal surgeries (cervical and thoracic/lumbar) was undertaken. Data gathered included procedure, operative duration, presence of background music, and noise information. Noise information included maximum decibel level (MDL), Peak level (LCPeak), Equivalent continuous sound pressure level, time weighted average (TWA), dose, and projected dose. Noise measurements were compared with baseline controls with and without music (empty ORs). Two hundred seven noise recordings were analyzed. One hundred eighteen of those being spinal surgeries, 49 baseline recordings without music, and 40 with music. Maximum decibel level reached a maximum value of 111.5 dBA, with an average amongst surgical recordings of 103 dBA. Maximum decibel level exceeded 85 dBA in 100% of cases and was greater than 100 dBA in 78%. The maximum LCPeak recorded was 132.9 dBC with an average of 120 dBC. Furthermore, the average dose was 7.8% with an average projected dose of 26.5%. The highest dose occurred during a laminectomy at 72.9% of daily allowable noise. Maximum projected dose yielded 156% during a 3-level anterior cervical discectomy and fusion. Spine surgeons are routinely exposed to damaging noise levels (>85 dBA) during operative intervention. With spine surgeons often performing multiple surgeries a day, the cumulative risk of noise exposure cannot be ignored. The synergistic effects of continuous and impact noise places spine surgeons at risk for the development of occupation-related NIHL.

Visual Facial Enhancements Can Significantly Improve Speech Perception in the Presence of Noise.

Human speech perception is generally optimal in quiet environments, however it becomes more difficult and error prone in the presence of noise, such as other humans speaking nearby or ambient noise. In such situations, human speech perception is improved by speech reading, i.e., watching the movements of a speaker's mouth and face, either consciously as done by people with hearing loss or subconsciously by other humans. While previous work focused largely on speech perception of two-dimensional videos of faces, there is a gap in the research field focusing on facial features as seen in head-mounted displays, including the impacts of display resolution, and the effectiveness of visually enhancing a virtual human face on speech perception in the presence of noise. In this paper, we present a comparative user study ( N=21) in which we investigated an audio-only condition compared to two levels of head-mounted display resolution (1832×1920 or 916×960 pixels per eye) and two levels of the native or visually enhanced appearance of a virtual human, the latter consisting of an up-scaled facial representation and simulated lipstick (lip coloring) added to increase contrast. To understand effects on speech perception in noise, we measured participants' speech reception thresholds (SRTs) for each audio-visual stimulus condition. These thresholds indicate the decibel levels of the speech signal that are necessary for a listener to receive the speech correctly 50% of the time. First, we show that the display resolution significantly affected participants' ability to perceive the speech signal in noise, which has practical implications for the field, especially in social virtual environments. Second, we show that our visual enhancement method was able to compensate for limited display resolution and was generally preferred by participants. Specifically, our participants indicated that they benefited from the head scaling more than the added facial contrast from the simulated lipstick. We discuss relationships, implications, and guidelines for applications that aim to leverage such enhancements.

Estimating the number of occupants and activity intensity in large spaces with environmental sensors

Recently, occupant-centered control models have been widely discussed, with intelligent control models looking for more refined and dynamic regulation based on occupant information. This article introduced a novel method for using environmental sensors and machine learning algorithms to identify the number of occupants and activity intensity in large spaces. A multi-functional space was monitored for approximately two months using PIR, CO2, sound decibel, temperature and humidity sensors. To address the challenge of identifying the number of occupants in large spaces, the study proposed a non-uniformly distributed interval of occupant numbers that offsets the small fluctuations in the number of people. The study also demonstrated that PIR and CO2 level measurements could be used to estimate the headcount interval with an accuracy rate of 84.5%. Furthermore, the study employed K-means clustering to identify low-, medium-, and high-level activities in the studied space, achieving an overall accuracy rate of 89.3%. A new metric of activity intensity was introduced to measure the activities carried out indoors, which incorporated CO2 and sound decibel levels, PIR readings, and the number of occupants. This proposed metric was found to be appropriate for quantifying the activity intensity in the studied space. Overall, the method presented in this study provided a promising approach for enabling occupant-based control strategies that leverage advanced sensor data to optimize building service systems in large spaces.

Seeger Lecture, Society for Ethnomusicology Virtual Meeting 2021

Seeger Lecture, Society for Ethnomusicology Virtual Meeting 2021

LabVIEW-based fire extinguisher model based on acoustic airflow vibrations

In recent years, soundwave-based fire extinguishing systems have emerged as a promising avenue for fire safety measures. Despite this potential, the challenge is to determine the exact operating parameters for efficient performance. To address this gap, we present an artificial intelligence (AI)-enhanced decision support model that aims to improve the effectiveness of soundwave-based fire suppression systems. Our model uses advanced machine learning methods, including artificial neural networks, support vector machines (SVM) and logistic regression, to classify the extinguishing and non-extinguishing states of a flame. The classification is influenced by several input parameters, including the type of fuel, the size of the flame, the decibel level, the frequency, the airflow, and the distance to the flame. Our AI model was developed and implemented in LabVIEW for practical use.&#x0D; The performance of these machine learning models was thoroughly evaluated using key performance metrics: Accuracy, Precision, Recognition and F1 Score. The results show a superior classification accuracy of 90.893% for the artificial neural network model, closely followed by the logistic regression and SVM models with 86.836% and 86.728% accuracy, respectively. With this study, we highlight the potential of AI in optimizing acoustic fire suppression systems and offer valuable insights for future development and implementation. These insights could lead to a more efficient and effective use of acoustic fire extinguishing systems, potentially revolutionizing the practice of fire safety management

0935 An Investigation of ICU Ambient Noise Levels as a Potential Source for Poor Sleep Outcomes in a Community Hospital Setting

Abstract Introduction Patients in the intensive care unit (ICU) are subject to multiple necessary diagnostic and therapeutic interventions throughout the course of their treatment that contribute to sleep deprivation. These measures increase ambient noise, impacting patient morbidity and mortality by exacerbating confusion, ICU-related delirium, recovery time, and long term sequelae associated with Post-Intensive Care Syndrome. The World Health Organization suggests critically-ill patients not exceed exposure to sound levels higher than 35-40 decibels (dB). In this study, we measured ICU sound levels in a community hospital setting to support intervention with conservative bundle measures or behavior modification with a visual noise monitoring device. Methods This study took place over two months (October-November, 2021) in the critical care unit of St Agnes Medical Center in Fresno, CA. Ambient noise was monitored using a sound decibel meter (Gain Express Holdings, SLM-25) connected to recording software that measured the decibel levels at 1-minute intervals for 24 hours in three areas: two central stations (Station A and B) and one occupied patient room, equidistant to both central stations. The monitor data was exported to Microsoft Excel (2020 version; Microsoft Corp, Redmond, WA, USA) for analysis. Data from each sample was expressed as M±SE (95% confidence interval). Results Both central stations had average levels of 44.1dB± 4.7 and 48.0dB± 4.3, with a frequency range of 40-50 dB greater than 50% of the time. Station A had a frequency range of 50-60 dB approximately 11% of the time and Station B at 30% of the time. The occupied patient room had average levels of 48.0dB± 5.4, with frequency of 40-50 dB greater than 50%, and levels 50-60 dB greater than 30% of the time. Conclusion ICU’s with higher than recommended ambient sound levels may benefit from appropriate intervention such as visual noise monitoring devices or order-sets with protocols on equipment/staff phone volume, earplugs for patients, and limiting staff conversation to distances away from the bedside. Support (if any)

Comparison of the efficacy of non-pharmacological interventions during the heel stick procedure on pain level, duration of crying, and voice decibel of newborns: a randomized controlled trial

Objective: To compare the efficacy of different non-pharmacological interventions (kangaroo care, cuddling, playing white noise, ambient sound) applied to newborns during the heel stick procedure on newborns’ pain level, duration of crying, and voice decibel. Methods: This is a prospective, randomized controlled trial including pre- and post-tests of four groups. The setting is a neonatal intensive care unit in Türkiye. One hundred and thirty-six newborns were recruited. Newborns were randomly assigned to four groups (i) kangaroo care, (ii) cuddling, (iii) white noise, and (iv) ambient sound. Pain measures were recorded 1 minute before, during, and 3 minutes after blood collection based on the Neonatal Infant Pain Scale (NIPS). Results: There was a significant difference between the pain levels (χ2=16.910, p=.001) and durations of crying (χ2=13.888, p=.003) during the heel stick procedure of the newborns depending on the non-pharmacological intervention. The pain levels of newborns who received kangaroo care were significantly lower compared to those who were listened to ambient sound during the procedure. The newborns’ durations of crying who received kangaroo care and who were lapped by their mothers during the heel stick procedure were also lower than those who are listened to ambient sound. There was no significant difference between the highest sound decibel levels of newborns after the procedure due to the non-pharmacological intervention applied during the heel stick procedure. Conclusion: Kangaroo care was more effective in reducing pain level and duration of crying. The non-pharmacological interventions had no effects on the highest sound decibel levels of newborns.

Inverse Design Method for Low-Boom Supersonic Transport with Lift Constraint

The low-boom inverse design method is of great interest for the preliminary design of supersonic transport (SST), owing to its good capability of reducing sonic boom at low computational cost. However, the main challenge is how to prescribe an attainable target. This paper proposes an inverse design method using a new target-generation strategy to address this challenge. Unlike existing methods such as the Jones–Seebass–George–Darden method and the mixed-fidelity inverse design method [the Li–Shields–Geiselhart (LSG) method], the proposed method directly parameterizes the near-field overpressure distribution of a reference configuration and minimizes the ground perceived level in decibels (PLdB) predicted by solving the augmented Burgers equation to obtain an optimal target distribution, subject to cruise lift and volume constraints. The proposed method is demonstrated by the Japan Aerospace Exploration Agency (JAXA) Wing Body case, which shows that it mitigates sonic boom under lift constraint and achieves a reduction of 2.07 PLdB more than the LSG method. The proposed method is applied to the low-boom design of a large SST configuration called NPU-T7104, which is close in size to the Tupolev Tu-144; results show that aerodynamic performance is maintained while shock wave coalescence is effectively prevented, and ground-boom intensity is dramatically reduced.

Material Parameter Assessment for Noise-Absorbing Devices in Shoe Heels

Noise is a mixture of sounds of various frequencies that irritate human beings. Today, noise is considered an “invisible” pollutant that raises great concern, especially in cities. Prolonged exposure to noise, either in everyday life or at the workplace, may cause health problems including high blood pressure and heart diseases. Noise may have negative impacts on reading, attention, problem-solving, and memory. One of the solutions to this problem is the reduction of the decibel level (dB). This article studies the noise-absorbing characteristics of polymer materials used in shoe sole production. The authors suggest producing noise-absorbing caps from the FLEX material. Additive technologies were used in cap production. This article presents the results of the research on the use of the FLEX plastic for noise-absorbing shoe heel caps. When using the shoes with heel caps made of FLEX plastic, the noise level on porcelain stoneware reduced 5.61 times, and 12.79 times on laminate flooring. The authors prove that noise-absorbing heel caps can reduce the noise levels at workplaces and public organizations, which may have a positive effect on the environment.