Search Results (28)

Motorcycle horns are a dominant source of urban noise in many Southeast Asian cities, driven by high two-wheeler density and limited public transport infrastructure. Although automobiles have been in use for over a century, regulations governing horn design and volume control remain inadequate. This study investigates horn use behavior in Vietnamese urban traffic, identifying distinct acoustic patterns categorized as “attention” and “warning” signals. Measurements conducted in an anechoic chamber reveal that these patterns can increase sound pressure levels by up to 17 dB compared to standard horn use, with notable differences in frequency components. These levels often exceed the daytime noise thresholds recommended by the World Health Organization (WHO), indicating potential risks for adverse health outcomes, such as elevated stress, hearing damage, sleep disturbance, and cardiovascular effects. The findings are contextualized within broader efforts to manage traffic noise in rapidly developing urban areas. Drawing parallels with studies on aircraft noise exposure in Japan, this study suggests that long-term exposure, rather than peak noise levels alone, plays a critical role in shaping community sensitivity. The study results support the need for updated noise regulations that address both the acoustic and perceptual dimensions of road traffic noise. Full article

For animals that typically live in groups or family units, being isolated from their conspecifics can be stressful. Horned passalus beetles (genus Odontotaenius), inhabit decaying logs in forests in the eastern United States. While not a truly social insect, they do coinhabit logs and maintain family units, and they are known to communicate with each other using stridulations that produce varying types of “chirps”. This project investigated if the auditory environment within these logs affects the beetles, specifically by exposing larval or adult beetles in a lab to sounds of (1) other beetles chirping, (2) no sound, or (3) the sounds of crickets, for varying time periods. Beetles were weighed before and after the exposures to determine changes in body mass. Beetle larvae experienced the slowest growth rates when listening to crickets or no sound, and the highest growth rates when hearing adult chirps. Adult beetles experienced mass losses in the treatments without beetle sounds, and this finding was replicated in three different experiments. The mass loss was greatest in the experiment that had the longest duration. The fact that the mass losses were observed in both the silent treatment, plus the treatment of cricket sounds, indicates that the lack of conspecific sounds (of other passalus beetles) was driving the effect. Surprisingly, there was no added effect of nematode parasitism on adult weight loss. Also, there was no evidence that the beetles were foraging less in the treatments without beetle sound, which suggest those beetles were experiencing elevated metabolism. The reduced growth rates and lost mass are signs that the beetles experienced chronic stress when deprived of the sounds of their kin. Combined, these experiments demonstrate how the acoustic environment, and especially the sounds of other beetles, is important to the lives of these insects, perhaps owing to the fact that they live in dark tunnels. Full article

This work presents the design and implementation of an emergency sound detection and localization system, specifically for sirens and horns, aimed at enhancing road safety in automotive environments. The system integrates specialized hardware and advanced artificial intelligence algorithms to function effectively in complex acoustic conditions, such as urban traffic and environmental noise. It introduces an aerodynamic structure designed to mitigate wind noise and vibrations in microphones, ensuring high-quality audio capture. In terms of analysis through artificial intelligence, the system utilizes transformer-based architecture and convolutional neural networks (such as residual networks and U-NET) to detect, localize, clean, and analyze nearby sounds. Additionally, it operates in real-time through sliding windows, providing the driver with accurate visual information about the direction, proximity, and trajectory of the emergency sound. Experimental results demonstrate high accuracy in both controlled and real-world conditions, with a detection accuracy of 98.86% for simulated data and 97.5% for real-world measurements, and localization with an average error of 5.12° in simulations and 10.30° in real-world measurements. These results highlight the effectiveness of the proposed approach for integration into driver assistance systems and its potential to improve road safety. Full article

Acoustic monitoring facilitates the detailed study of herbivore grazing by generating a timeline of sound bursts associated with jaw movements (JMs) that perform bite or chew actions. The unclassified stream of JM events was used here in an observational study to explore the notion of “grazing time”. Working with shepherded goat herds in a wooded landscape, a horn-based acoustic sensor with a vibration-type microphone was deployed on a volunteer animal along each of 12 foraging routes. The software-generated timeline of unclassified JMs contained a total of 334,582 events. After excluding rumination bouts, minutely JM rates showed a broad, non-normal distribution, with an overall mean of 61 JM min⁻¹. The frequency distribution of inter-JM interval values scaled logarithmically, with a peak in the region of 0.43 s representing a baseline interval that generates the unconstrained, more-or-less regular, rhythm of jaw movement (≈140 JM min⁻¹). This rhythm was punctuated by interruptions, for which duration scaled logarithmically, and which were primarily related to the search phase of the intake process. The empirical time accumulation curve shows the contribution of the inter-JM interval to the total foraging time and provides a penetrating profile of how the animal interacted with the foraging environment. The sum total of time along a foraging route spent at a near-potential JM rate was only ≈1 h, whereas sub-potential rates containing intervals as long as ≈30 s accounted for the bulk of the foraging route. The dimensionless behavioral grazing intensity was defined as the product of the number of ingestive JMs performed and the baseline interval, divided by the duration of the foraging route (excluding rumination). Values were mostly <0.5 for the foraging routes examined. This has implications for how animal presence should be translated to grazing pressure and for how long animals need to forage to meet their nutritional requirements. Full article

Katydids employ acoustic signals to communicate with others of their species and have evolved to generate sounds by coupling the anatomical structures of their forewings. However, some species have evolved to implement an additional resonance mechanism that enhances the transmission and sound pressure of the acoustic signals produced by the primary resonators. Secondary resonators, such as burrow cavities or horn-shaped structures, are found in the surrounding environment but could also occur as anatomical modifications of their bodies. Chamber-like structures have been described in species of katydids with modified pronota or wings. It has been shown that these modified structures directly affect the transmission and filtering of acoustic signals and can function as a Helmholtz resonator that encapsulates the primary sound source. By morphological and acoustic analysis, we describe a new genus of Conocephalinae and investigate the physical properties of their sound production structures for three new species from the Andes of Colombia and Ecuador. Males of the new genus, here described as Tectucantus n. gen., have a characteristic inflated pronotum enclosing the reduced first pair of wings and extending rearward over the first abdominal segments. We test the hypothesis that the pronotal cavity volume correlates with the carrier frequency of specific calls. The cavity of the pronotal chamber acts as a Helmholtz resonator in all three Tectucantus species and, potentially, in other distantly related species, which use similar secondary body resonators. Full article

Electric and hybrid vehicles are known for their significant reduction in road noise. However, concerns have emerged regarding their silent operation, potentially increasing risks for other road users. To mitigate this, the Acoustic Vehicle Alert System (AVAS) has been mandated by regulations such as R138 by UNECE in the USA and Europe. This regulation dictates the generation of sound in electric vehicles of categories M and N1 during normal, reverse, and forward motion without the internal combustion engine engaged. Compliance involves meeting specific sound requirements based on vehicle mode and condition. This paper introduces a Python-based approach to designing digital horn sounds, leveraging music theory and signal processing techniques to replace traditional mechanical horns in electric vehicles equipped with AVAS devices. The aim is to offer a practical and efficient means of generating digital horn sounds using this software. The software includes an application capable of producing and customizing horn sounds, with the HornSoundGeneratorGUI class providing a user-friendly interface built with the Tkinter library. To validate the digital horn produced sounds by the software and ensure compliance with AVAS regulations, comprehensive electrical and acoustic tests were conducted in a fully equipped quality laboratory. The results demonstrated that the sound levels achieved met the required 105–107 dB/2 m standard specified by the regulation. Full article

Sonic-IR, which detects defects based on the temperature rise due to frictional heating at the defect faces under ultrasonic excitation, has an advantage in the detection of closed defects. However, in the conventional sonic-IR method, an acoustic energy is directly input from an ultrasonic transducer to the test object via an ultrasonic horn, which may give some scratches and deformation to the test object. To avoid such a problem, we have developed a new sonic-IR method using an ultrasonic wave input via water, and the practicability of the proposed method for the detection of fatigue crack has been experimentally demonstrated. This study presents the results of an investigation of the effect of immersion conditions on heat generation at defects in the proposed method. Full article

This paper presents a novel piezoelectric micromachined ultrasonic transducer (PMUT) with theoretical simulation, fabrication, and testing. Conventional methods using a PCB or an external horn to adjust the PMUT acoustic field angle are limited by the need for transducer size. To address this limitation, the stepped-tube (expanded tube) backside cavity PMUT has been proposed. The stepped-tube PMUT and the tube PMUT devices have the same membrane structure, and the acoustic impedance matching of the PMUT is optimized by modifying the boundary conditions of the back cavity structure. The acoustic comparison experiments show that the average output sound pressure of the stepped-tube backside cavity PMUT has increased by 17%, the half-power-beam-width (θ_-3db) has been reduced from 55° to 30° with a reduction of 45%, and the side lobe level signal is reduced from 147 mV to 66 mV. In addition, this work is fabricated on an eight-inch wafer. The process is compatible with standard complementary metal oxide semiconductor (CMOS), conditions are stable, and the cost is controllable, plus it facilitates the batch process. These conclusions suggest that the stepped-tube backside cavity PMUT will bring new, effective, and reliable solutions to ranging applications. Full article

Ultrasound (US)-assisted synthesis of a N-doped TiO₂ catalyst supported on magnetically separable Fe₃O₄@ZnO particles and its subsequent application for catalytic desulfurization were performed in the present work. The catalyst was also synthesized conventionally to compare the role of acoustic cavitation (US horn working at 20 kHz frequency) in improving the catalyst characteristics. The effects of different ultrasonic (US) power (80 W to 120 W) and duration (15 min to 75 min) were studied to elucidate the best operating conditions for obtaining the minimum particle size of the catalyst. Under optimal conditions of 80 W power and 30 min of time, a minimum particle size of 31.22 μm was obtained. The particle size for the conventionally synthesized catalyst was 806.4 µm, confirming that the particles were agglomerated in the absence of ultrasound. The synthesized catalyst was used for the desulfurization of thiophene to assess the performance of the catalyst, along with a comparative study between the conventionally synthesized catalyst and that obtained using the US-assisted approach. It was evident that the performance of the catalyst synthesized sonochemically was superior, as US enhanced the activity of the catalyst by reducing the particle size and achieving homogeneity. The desulfurization achieved using the sonochemically synthesized catalyst was 47% in 100 min at a 2 g/L catalyst dose and a 3 mL/L H₂O₂ dose. The desulfurization was only 25% using the conventionally synthesized catalysts under the same operating conditions. Overall, the present work demonstrates the advantages of US in improving the catalyst characteristics, as well as the successful application of catalyst in desulfurization. Full article

This study investigated the effect of a new type of ear pads for ski helmets on the hearing performance of 13 young adults (mean age: 22 years). Free-field hearing thresholds and sound localization performance of the subjects were assessed in three conditions: without helmet, with a conventional helmet and with the modified helmet. Results showed that the modified helmet was superior to the conventional helmet in all respects, but did not allow for a performance level observed without a helmet. Considering the importance of precise hearing and sound localization during alpine skiing, acoustically improved ear pads of ski helmets, as demonstrated in this study, can essentially contribute to enhancing the safety on ski slopes. Full article

The core of the ultrasonic machining system is the acoustic vibration component. Due to the inconsistency of the assembly conditions between the junction surfaces of the acoustic vibration component, the resonant frequency of the ultrasonic acoustic vibration component after the size adjustment of the ultrasonic horn is low, and the Impedance mismatch occurs in the ultrasonic system. In this paper, considering the influence of assembly conditions, the optimal assembly parameters were studied to reduce the junction surface’s influence on the ultra-sonic horn’s performance parameters. The paper analyzed the assembly structure, assembly parameters, and static and dynamic performance parameters of the acoustic vibration components and established a static and dynamic performance parameter measurement system. The assembly parameters of the ultrasonic acoustic vibration components were analyzed and determined. The static performance parameters of the ultrasonic acoustic components were measured and analyzed for the assembly parameters of the junction surface at the ultrasonic horn and the straight-edged knife. The optimal assembly parameters were preliminarily determined based on the analysis of the static performance parameters. The optimal assembly parameters of the junction surface of the ultrasonic horn and the straight-edged knife were determined through the measurement and analysis of the dynamic performance parameters of the two junction surfaces. The work is the basis for the adjustment of the ultrasonic horn. It also provides a basis for improving the working performance, manufacturing precision, and production efficiency of the ultrasonic horn while further popularizing the application of ultrasonic processing. Full article

A non-intrusive cleaning method for boiler tubes at Sasol Synfuels power station at Secunda, in the Mpumalanga province of South Africa, is preferred over conventional methods that require boiler shutdown. The elected non-intrusive cleaning method utilizes sound energy waves, produced by an acoustic horn. Due to the nature of sound propagation and the effectiveness required, there is a requisite to control and operate the sonic horn. If the acoustic horn’s sound frequency is too low, it will produce higher sound energy waves that will resonate with the plant’s harmonious frequency and cause structural damage. Conversely, if the sonic horn’s sound frequency is too high, excessive noise levels may be reached and annoy plant personnel. To prevent these undesirable outcomes posed by adopting acoustic cleaning, there needs to be a regulatory system incorporated into the configuration to mitigate vibrations and limit noise. The regulatory system comprises a control system that drives the acoustic horn’s sound frequency as intended through a set point. The designed control system meets the anticipated requirements, such that it has an ideal transient response of 0.562 s, a steady-state error achieved in 1.05 s, with 0.201% overshoot, and most importantly the closed-loop system is stable. Full article

A vibration absorber consisting of a one-dimensional waveguide with a reflectionless termination extracts vibrational energy from a structure that is to be damped. An optimum energy dissipation occurs for the so-called power adjustment, i.e, the same level of resistance and the opposite reactance of structure and absorber. The dimensioning of these impedance parameters on the base of the classic second order “two-way” wave equation provides analytical solutions for a few simple waveguide shapes; solutions for all other waveguides are only accessible via numerical finite-element computation. However, the competing first order “one-way” wave equation allows for an analytical conception of both the known broadband vibration absorber and the “Acoustic Black Hole” absorber. For example, for an exponential waveguide, the two-way calculation shows no resistance (and hence no real wave propagation) below a cut-off frequency, while the one-way wave equation predicts absorption in the whole frequency range. Full article

Car horns were originally installed in vehicles for safety. However, many urban areas in several countries face noise problems related to the use of car and motorbike horns. To propose measures to suppress the use of horns, relationships between horn use and factors including driver awareness and behavior, traffic environment, and the transportation system should be investigated. The present study therefore conducted surveys to grasp the current circumstances of horn use and traffic at urban intersections in Taiwan. The relationship between horn use and the traffic volume of standard-sized vehicles was found. According to an analysis of horn use during traffic signal cycles, in many cases, horns were honked after entering intersections to turn left. In particular, horns were honked when the driver waited more than 4 s for the car in front to start moving after the green light allowing left turns was turned on. An analysis of noise levels at intersections showed that the maximum noise level value (L_Amax) could be reduced if vehicle horns were not used. Multiple regression analysis also indicated that L_Amax values increased with the frequency of horn use. The equivalent continuous A-weighted sound pressure level (L_Aeq,10min) did not change with driver horn use, and increased with the traffic volume of motorcycles. Full article

Several ultrasonic cleaning tanks (UCTs) had a problem: a manufacturer complained that there were damages to cleaning objects, they were unclarified, and it needed to be abruptly solved. To investigate and solve the problem, a small UCT filled with 3.92 L of water, with a frequency of 28 kHz, two horn transducers, and a total power of 100 W was built for simulation and experiment. A built tank body material of UCT can be adjustable to acrylic, glass, and stainless steel. Since the cavitation causing the cleaning relates to acoustic pressure, harmonic response analysis (HRA) in ANSYS software was employed to calculate the acoustic pressure inside the UCT for different designs such as mentioned materials, power, thickness, volume, and frequency. The HRA results revealed uneven acoustic pressure depending on the tank designs, consistent with foil corrosion and power concentration experiments. Furthermore, using the tank body material with acrylic, glass, and stainless steel provided the highest, moderate, and lowest acoustic pressure levels, respectively. The uneven acoustic pressure resulted from the differences in material transmission coefficients. In addition, the damage occurred because of improper tank design, resulting in excessive acoustic pressure. Therefore, the tank design is indispensable in designing high-efficiency UCTs to reduce damage and meet customer requirements. Full article