The paper presents an in-depth analysis of the soundscape within Sarek National Park, the oldest national park in Europe, situated in Lapland, northern Sweden. The comprehensive acoustic measurements, ambisonic recordings, and 360X video recordings were carried out during a scientific expedition in the summer of 2020. The aim of the paper is to show the soundscape analysis of carefully selected characteristic locations in various parts of the valley. The paper extensively discusses the findings derived from the recorded data using both classical acoustic methods and the soundscape approach. The classic acoustic parameters, commonly employed in environmental acoustics as well as eco-acoustic indices such as: ACI (acoustic complexity index), ADI (acoustic diversity index), AEI (acoustic evenness index), NDSI (normalized difference soundscape index), BIO (energy level of biophony), amplitude index (M), and total entropy (H) were calculated. To gain further insights, listening tests, facilitated through virtual reality tools, were conducted, enabling participants to engage in soundwalk experiences. By employing a combination of traditional acoustic methods and innovative soundscape approaches, the paper presents a holistic evaluation of the auditory environment in Sarek National Park. The main contribution of the presented research is providing new data from the unique, geographically inaccessible region of the world, the Sarek National Park. This research not only enriches our understanding of the national park’s soundscape but also offers valuable insights into the interaction between the natural environment and human perception of sound.

The growing amount of used tires presents many environmental challenges around the world. Therefore, new ways to reuse used tires are being sought. One of the uses of waste tires is in sound-insulating constructions. Waste tires can be shredded into granules, which can be further devulcanized to increase their porosity. These granules can then be glued to panels and used in sound-insulating structures. Acoustic louvers were investigated in this study, with the louvers’ plates covered with rubber granule panels. Sound absorption parameters of rubber granule panels were tested across frequency bands ranging from 160 Hz to 5000 Hz. The results showed the normal incidence sound absorption coefficient reached 0.87–0.96 at 3150 Hz for 12 mm rubber granule plates. Measurements were conducted in a semi-anechoic chamber. The study has shown that rubber louvers can reduce the sound pressure level by 8 dB–12 dB, depending on the composite of the rubber granule panels and the tilt angle of the louvers’ plates.

This article presents a comprehensive acoustic study of paper-based building products: cellulose wool, paperboard, corrugated cardboard, and honeycomb panels. The material configurations included the intact form as well as the various modifications, i.e., density variation, multiple-layered staking, perforation or acoustic metamaterial setup. Tests covered acoustic absorption and insulation properties, with the last examined under excitation of both a plane wave and a diffused field. Additionally, the cellulose wool is provided with the characteristic impedance and propagation wavenumber results; and the paperboard was tested for its dynamic elastic and damping properties. The paper-based products, giving their weight, prove to be a convincing replacement for conventional materials by both absorptive and insulation performance. The maximum acquired sound reduction index, for exceptionally lightweight (2.2 kg/m2) paper double-wall metamaterial structure, reached 26 dB.

The research described in the article addresses the problem of measurement, prediction and practical use of the acoustic properties of materials determined in an impedance tube. The aim of the research was to develop a simple calculation model for the insertion loss of small machinery enclosures, based on the normal incidence sound transmission loss and the normal incidence sound absorption coefficient of porous and fibrous materials. Both experimental and model tests were carried out on materials such as mineral wool, melamine foam and rebonded polyurethane foam.
Assessing the absorption properties of the tested porous and fibrous materials was performed using selected theoretical models, relating the calculations of the normal incidence sound absorption coefficient to measurements of this parameter conducted using an impedance tube. The application of the modified Allard and Champoux model brought the best results with the smallest discrepancies of the obtained results in relation to the experimental tests.
Assessing the sound-insulating properties of the tested mineral wool was carried out using the proposed calculation model for the normal incidence sound transmission loss, relating the obtained results to measurements conducted using an impedance tube. The assessment of the sound-insulating properties of porous and fibrous materials was performed using the proposed calculation model for insertion loss, which was validated using two prototype test stands for determining the insertion loss of cubic enclosures, in this case with walls made of porous and fibrous materials. Satisfactory results were obtained for engineering applications in the calculation results using the proposed models with respect to measurements. The results may have practical applications in assessing the effectiveness of acoustic enclosures, in which the basic construction material is an appropriate porous or fibrous plate, selected to have both sound-absorbing and sound-insulating properties.

The article addresses the problem of assessing the impact of road modernization on improving the acoustic environment. It formulates a hypothesis about the advisability of adopting the scalar dimension of the decibel space to describe acoustic hazards. It is proposed to reduce the analysis of changes in sound levels to the analysis of changes in the coefficient of exceedance of the recommended noise levels. Its value is determined by the decibel relation of dividing sound levels. The basis for the assessment of the effectiveness of the adopted solution was the analysis of the statistical characteristics of monitored exceedances of recommended noise levels, considered through the prism of the current and proposed measure. They showed greater sensitivity of the proposed coefficient in the assessment of the improvement of the acoustic climate caused by road modernization. For example, the median noise level for nights before the road modernization was 66.9 dB(A), and after the modernization 65.6 dB(A). However, the coefficient of exceedances decreased by approximately 25 %. Numerical simulations, in accordance with the Cnossos noise model, showed that reducing the speed by 10 km/h will reduce the coefficient of exceedances by approximately 20 %.

There is no doubt that traffic noise has become one of the main sources of urban noise, and the electric bus, as an important means of transport frequently used by people in daily life, has a direct impact on the psychological and auditory health of passengers due to its interior noise characteristics. Consequently, studying electric bus sound quality is an important way to improve vehicle performance and comfort. In this paper, eight electric buses were selected and 64 noise samples were measured. Acoustic comfort was taken as an evaluation index, professionals were organized to complete the subjective evaluation tests for all noise samples based on rank score comparison (RSC). And nine psycho-acoustic objective parameters such as loudness, sharpness and roughness were calculated using ArtemiS software to establish the sound quality database of electric buses. Aiming at the practical application requirements of high-precision modeling of acoustic comfort in vehicles, this paper presented two improved extreme gradient boosting (XGBoost) algorithms based on grid search (GS) method and particle swarm optimization (PSO), respectively, with objective parameters and acoustic comfort as input and output variables, and established three regression models of standard XGBoost, GS-XGBoost and PSO-XGBoost through data training. Finally, the calculation results of three indexes of average relative error, square root error and correlation coefficient indicate that the proposed PSO-XGBoost model is significantly better than GS-XGBoost and standard XGBoost, with its prediction accuracy as high as 97.6 %. This model is determined as the evaluation model of interior acoustic comfort for this case, providing a key technical support for future sound quality optimization of electric buses.

Ultrasonic haptic technology is one of the more interesting novel technologies being intensively developed in recent years. Such technology has a number of undoubted advantages and potential applications, but it can also be a source of ultrasonic noise. Pursuant to the provisions of the labor law, ultrasonic noise at a high sound pressure level can be a harmful factor for human health. The article presents the results of the assessment of ultrasonic noise emitted by an ultrasonic haptic device and the assessment of exposure to noise of a person using the device. The tests were carried out using one of the haptic devices readily available on the market. Ultrasonic noise emission tests were carried out around the device, at selected points placed on the surface of a hemisphere of a radius of 0.5 m, for various haptic objects. The analyzed parameter was the equivalent sound pressure level in the 1~3 octave band with a center frequency of 40 kHz. Variable sound pressure levels ranged from 96 dB to 137 dB. Noise exposure tests were carried out both using the KEMAR measurement dummy and with test participants of different heights. In most cases, the sound pressure level exceeded 110 dB, and in the worst case it exceeded 131 dB. Comparison of the results of ultrasonic noise assessments with the permissible values of this noise in the working environment shows that in the case of prolonged or improper use of the device, the permissible values may be exceeded.

Spotting a significant number of drones flying near the entrance of a beehive during late Spring could indicate the occurrence of swarming mood, as the the surge in drone presence is related to an overcrowded hive. Swarming refers to a natural reproductive process witnessed in honey bees, wherein half of the bee colony departs from their hive alongside the aging queen. In the paper, we propose an early swarming detection mechanism that relies on the behavior of the drones. The proposed method is based on audio signals registered in a close proximity to the beehive entrance. A comparative study was performed to find the most effective preprocessing method for the audio signals for the detection problem. We have compared the results for three different power spectrum density coefficients estimation methods, which are used as an input of an autoencoder neural network to discriminate drones from worker bees. Through simulations employing real-life signals, it has been demonstrated that drone detection based solely on audio signals is indeed feasible. The attained level of detection accuracy enables the creation of an efficient alarm system for beekeepers.

Geminates (such as the double /k/ in Polish lekki “light”) form a group of consonants that are mainly characterized by longer durations than the corresponding singletons. Most of the research has concentrated on durational and spectral properties of geminates in contrast to singletons. Much less attention has been paid to the realization of the voicing contrast in geminates and whether it is differently implemented than in singletons. In the current study, we contribute to this research with the data from Polish stop geminates. To this end, a total of 49 native speakers of Polish produced all stop geminates and corresponding singletons in wordforms of the same phonological make-up. The measurements included closure duration, voicing ratio, duration and mean intensity of the release burst. The results showed that the voicing ratio was 0.69, classifying Polish stop geminates as mildly devoiced. There was a significant speaker-dependent variability in that some speakers devoiced all geminates, while others either partially devoiced or never devoiced. The analysis of interactions between geminates and singletons revealed that geminates cancelled voicing cues observed in singletons such as longer durations and lower intensity of the release burst. We discuss the current results in terms of voicing implementation in Polish and in relation to other geminating languages.

The research explores the production and critical evaluation of two distinct mixes of “Dancing Ends”, a musical composition by Łukasz Pieprzyk. These mixes were engineered using two cutting-edge spatial sound technologies: Dolby Atmos and Ambisonics. The recording process incorporated overdub and multitrack recording techniques. Once created, the mixes were evaluated using a method of direct rating, based on an average rank system from 1 to 5, adhering strictly to the (ITU-R, 2015) BS.1116-3 and (ITU-R, 2019) BS.1284-2 standards. Evaluation criteria included factors such as mix selectivity, depth, width, and height of the sound stage, sound envelopment, tonal brightness, and quality of source localization. Additionally, some criteria were specifically tailored to evaluate characteristics unique to the composition. The evaluations were performed on three different listening systems and environments: surround systems of 5.1 and 7.1.4, and binaural listening. Although Ambisonics’ mix received higher ratings in several categories, Dolby Atmos’ mix was preferred across all listening environments. The results underscore the potential benefits of employing spatial sound technologies in music production and evaluation, offering insight into the capabilities of Dolby Atmos and Ambisonics.

Residential bathroom drainage noise is a primary source of indoor noise that directly affects quality of life and physical and mental health. Therefore, based on the acoustic theory and the finite element simulation technology, this paper proposes a method to simulate the drainage noise characteristics and its impact range jointly using the flow and acoustic fields. The pressure at the pipe wall caused by the internal flow field of the bathroom drainage pipe is calculated by the Fluent software. Simulations are carried out with the Virtual Lab software to predict the drainage noise characteristics and spatial distribution and to analyse the influence of factors such as the door position, riser position, and the partition wall material on the noise distribution. The results show that drainage noise has prominent high-frequency characteristics, the position of the bathroom drainage pipes and doors affects the spatial noise distribution, and the sound insulation performance of a par- tition wall with ordinary fired bricks in the bathroom is slightly better than that of ordinary concrete bricks, lightweight aggregate concrete blocks or fly ash blocks. This paper provides a theoretical basis and practical reference for reducing the impact of residential drainage noise and creating a healthy and comfortable indoor acoustic environment.

This study investigates ultrasonic energy’s impact on enhancing the growth of Botryococcus braunii (B. braunii) microalgae. Microalgae, known for their advantages in greenhouse gas mitigation and biomass conversion, were subjected to various stressors, including ultrasonic waves, to optimize productivity. Ultrasonic waves induce acoustic cavitation, increasing membrane permeability and substrate conversion. The study examined the impact of energy and maximum pressure resulting from bubble collapse on the relative specific growth rate of B. braunii microalgae. It was observed that reproduction showed a promotive trend until the energy surpassed 30 kJ. However, when ultrasonic energy reached 18.2 kJ, reproduction was inhibited due to the maximum pressure generated during bubble bursting, which reached 5.7 µN/µm², leading to the suppression of reproduction upon encountering bubble collapse events. Under specific ultrasonic conditions (15.1 kJ energy, maximum pressure of 45.5 × 10⁵ Pa), a maximum specific growth rate of 0.329 ± 0.020 day⁻¹ in a two-day interval boosted B. braunii microalgae biomass productivity. These findings advance our understanding of ultrasonic wave effects on microalgae reproduction and underscore the potential for optimizing ultrasonic parameters to enhance biomass production.

To prevent important items from being replaced by a forgery, an ultrasonic fingerprint identification algorithm is proposed and an identification program is developed. A virtual prototype for the ultrasonic identification of ceramics is developed based on an ultrasonic detection card. This virtual prototype allows for the simultaneous transmission and acquisition of signals. Numerous experimental tests were conducted using this virtual prototype. The results demonstrate that the virtual prototype achieves accurate identification of ceramics. This virtual prototype lays a good foundation for the development of intelligent, automated, integrated, and miniaturized ultrasonic identification systems.

Features of nonlinear phenomena and, in particular, acoustic excitation of the entropy and relaxation modes in a liquid electrolyte with a chemical reaction are examined. The total range of frequencies of an exciter is considered, and the instantaneous dynamic equations are derived which govern perturbations in the secondary modes. The instantaneous leading-order acoustic forces of the secondary modes are evaluated. Examples of harmonic and nearly harmonic acoustic exciter are considered in detail. The difference in the nonlinear acoustic phenomena in an electrolyte and gases with relaxation mechanisms are specified and discussed.

Fidgety speech emotion has important research value, and many deep learning models have played a good role in feature modeling in recent years. In this paper, the problem of practical speech emotion is studied, and the improvement is made on fidgety-type emotion using a novel neural network model. First, we construct a large number of phonological features for modeling emotions. Second, the differences in fidgety speech between various groups of people were studied. Through the distribution of features, the individual features of fidgety emotion were studied. Third, we propose a fine-grained emotion classification method, which analyzes the subtle differences between emotional categories through Siamese neural networks. We propose to use multi-scale residual blocks within the network architecture, and alleviate the vanishing gradient problem. This allows the network to learn more meaningful representations of fidgety speech signal. Finally, the experimental results show that the proposed method can provide the versatility of modeling, and that fidgety emotion is well identified. It has great research value in practical applications.