Search Results (124)

This study aims to investigate the effects of phase synchronisation on tonal noise reduction in a multi-rotor UAV using an electronic phase-locking system. Experiments at the University of Bristol explored the impact of relative phase angle, propeller spacing, and blade geometry on acoustic performance, including psychoacoustic annoyance. Results show that increasing the phase angle consistently reduces the sound pressure level (SPL) due to destructive interference. For the two-bladed configuration, the highest noise reduction occurred at relative phase angle $\Delta \psi ={90}^{\circ }$, with a 19 dB decrease at the first blade-passing frequency (BPF). Propeller spacing had minimal impact when phase synchronisation was applied. The pitch-to-diameter ($P/D$) ratio also influenced results: for $P/D=0.55$, reductions ranged from 13–18 dB; and for $P/D=1.0$, reductions ranged from 10–20 dB. Maximum psychoacoustic annoyance was observed when propellers were in phase ($\Delta \psi =0^{\circ }$), while annoyance decreased with increasing phase angle, confirming the effectiveness of phase control for noise mitigation. For the five-bladed configuration, the highest reduction of 15 dB occurred at $\Delta \psi ={36}^{\circ }$, with annoyance levels also decreasing with phase offset. Full article

This paper presents an analysis of G. P. Telemann’s Sonata in C Major for Recorder and Basso Continuo (TWV 41:C2, Allegro), with the aim of investigating the occurrence of perceptual streams. The presence of perceptual streams in musical works helps to organise the sound stimuli received by the listener in a specific manner. This enables each listener to perceive the piece in an individual and distinctive manner, granting primacy to selected sounds over others. Directing the listener’s attention to particular elements of the auditory image leads to the formation of specific mental representations. This, in turn, results in distinctive interpretations of the acoustic stimuli. All of these processes are explored and illustrated in this analysis. Full article

This paper presents an experimental acoustic noise characterization of a switched reluctance motor (SRM) designed for a wind turbine pitch angle control application. It details the fixture design for holding and positioning the sound intensity probes, along with the essential hardware setup for conducting acoustic noise experiments. Additionally, the software configuration is described to ensure compliance with specific measurement requirements. To study the effect of speed and load variations on the motor’s acoustic noise characteristics, tests are conducted at various operating points. The tests employ pulse-width modulation (PWM) current control, operating at a switching frequency of 12.5 kHz. Sound pressure and sound intensity are measured across different operating conditions to determine the sound power and psychoacoustic metrics. Furthermore, the effect of different factors on the motor’s sound power level, as well as on psychoacoustic metrics such as sharpness, loudness, and roughness, is analyzed and discussed. Full article

The aim of our work was to investigate how electric guitar strings wear out. There are many myths about string wear. We decided to investigate what the wear process looks like in real life. In our work, sound processing methods such as DTFT and spectrogram were used. However, the most important research method is the use of time-frequency analysis to study the sound of the string and its wear process. Another key method used in our work is the application of a phenomenon known from psychoacoustics, pitch. In our work, we have been able to show that the use of pitch in combination with time-frequency analysis makes it possible to demonstrate string wear. This was not achievable for previously known methods. We have also shown that the string yield limit is exceeded immediately when the strings are placed on the guitar neck. This affects the sound equation of the string. In this work, we have proposed a transformation of the classical string equation so that it correctly describes the sound of the string as it is worn. The research method we have developed, combining pitch and time-frequency analysis, could presumably be used in the future to study the wear and tear of other vibrating systems, such as bridges and viaducts. Full article

As immersive audio is gaining popularity, the perceptual aspects of spatial sound reproduction become relevant. The authors investigate a measure related to spatial resolution, the Minimum Audible Angle (MAA), which is understudied in the context of Ambisonics. This study examines MAA thresholds in the horizontal plane in three ambisonic decoders—the Sample Ambisonic Decoder (SAD), Energy-Preserving Ambisonic Decoder (EPAD), and All-Round Ambisonic Decoder (AllRAD). The results demonstrate that the decoder type influences spatial resolution, with the EPAD exhibiting superior performance in MAA thresholds (${1.24}^{\circ }$ at $0^{\circ }$ azimuth) compared to the SAD and AllRAD. These differences reflect the discrepancies in the decoders’ energy vector distribution and angular error. The MAA values remain consistent between decoders up to ${30}^{\circ }$ azimuth but diverge significantly beyond this range, especially in the ${60}^{\circ }$–${135}^{\circ }$ region corresponding to the cone of confusion. The findings of this study provide valuable insights for spatial audio applications based on ambisonic technology. Full article

The evaluation of the acoustic quality of sound-emitting appliances is primarily conducted by measuring psychoacoustic parameters or by means of a jury study through subjective evaluation by respondents. This article aims to validate the developed model for evaluating the acoustic quality of washing machines. Three top-loading washing machines were used in three operating modes for validation. The measurement of the psychoacoustic parameters of these washing machines was carried out. Subsequently, in the evaluation process, a developed quality index was used, based on which a ranking of washing machines in terms of sound quality was determined. Subsequently, the results were validated using a questionnaire. By comparing the results of the evaluation of the questionnaire method and the application of the developed sound quality evaluation model based on the sound quality index, an almost perfect agreement is evident in determining the ranking of washing machines using both methods, as confirmed by statistical analysis. Developed a model for the evaluation of psychoacoustic quality and its application to the measured psychoacoustic parameters that can substitute the time-consuming methods of assessing sound quality through questionnaire surveys. The application of the developed method significantly reduces the evaluation time. Full article

Impact sound, particularly prevalent indoors, emerges as a major source of annoyance necessitating a deeper and more comprehensive understanding of its implications. This literature review provides a systematic overview of recent research developments in the study of impact sound annoyance, focusing on advances in the assessment of impact sound perception through laboratory listening testing and standardization efforts. This review provides a detailed summary of the listening setup, assessment procedure and key findings of each study. The studied correlations between SNQs and annoyance ratings are summarized and key research challenges are highlighted. Among the studies, considerable research effort has focused on the assessment of walking impact sound and the use of spectrum adaptation terms, albeit with inconsistent outcomes. Comparison with the previous literature also shows the influence of spatial and temporal characteristics of impact sound sources on perceived annoyance, with higher spatial fidelity leading to higher annoyance ratings. Furthermore, it has been shown that the consideration of non-acoustic factors such as noise sensitivity and visual features are important for the assessment. This review provides a comprehensive overview of recent advances in the understanding and assessment of impact sound annoyance and provides information for future research directions and standardization efforts. Full article

Unmanned aerial vehicles, particularly drones, have been increasingly deployed for different tasks in the community. They have become an important part of the economic and social benefits that society is exploiting from modern technology development. However, efforts are still required to further develop technologies which can mitigate the negative impacts. Among them, drone noise is considered a major health concern for the community. The present study undertakes an experimental investigation of the effectiveness of blade modifications on drone noise in an aeroacoustic wind tunnel facility. A quadcopter drone is programmed to operate in both hover and forward flights. Three modified blade configurations, including trailing-edge serrations combined serration–finlets, and an unmodified (baseline) blade, are manufactured. The far-field noise signals are recorded by two polar microphone arrays to quantify both the magnitude and directivity. The results show that all modified blades are able to reduce the drone noise at mid-to-high frequencies in both hover and forward flights, and this leads to a noticeable reduction in the overall sound pressure level. More importantly, the combined serration–finlet configuration outperforms all the other blades. Psychoacoustic analysis is also performed using the far-field acoustic time series. Interestingly, only the serration–finlet combination demonstrates a consistent reduction in the psychoacoustic annoyance levels, suggesting that it is important to use metrics from both acoustic and psychoacoustic analysis when developing noise mitigation strategies in the socio-economic context. Full article

To make guitars with high sonic quality, it is essential to understand the relationship between the physical characteristics of the selected materials and the acoustic characteristics of the final instrument and how they will be perceived. The selection of wood for the soundboard is a crucial step in the guitar-making process. One relevant physical characteristic is internal material damping, about which, however, only little is known in comparison to other characteristics such as density and Young’s modulus. The present study investigated the relationship of soundboard damping to both physical and perceptual aspects of guitar sound. Three similar steel-string guitars were built with the damping of their soundboards varying between low, mid and high. Measurements of the transfer function and the plucked tone decay of the final guitars were carried out. A listening test and a playing test were conducted. The participants were asked to rate preference and seven sound attributes comprising loudness and both spectral and temporal aspects. To prepare the listening test, a short sequence was recorded by a professional guitarist with each guitar. The results suggest that varying soundboard damping had no practically relevant influence on the physical and perceptual aspects of the sound of the guitar used in this study. Full article

Traffic safety experiments are often conducted in virtual environments in order to avoid dangerous situations and conduct the experiments more cost-efficiently. This means that attention must be paid to the fidelity of the traffic scenario reproduction, because the pedestrians’ judgments have to be close to reality. To understand behavior in relation to the prevailing audio rendering systems better, a listening test was conducted which focused on perceptual differences between simulation and playback methods. Six vehicle driving-by-scenes were presented using two different simulation methods and three different playback methods, and binaural recordings from the test track acquired during the recordings of the vehicle sound sources for the simulation were additionally incorporated. Each vehicle driving-by-scene was characterized by different vehicle types and different speeds. Participants rated six attributes of the perceptual dimensions: “timbral balance”, “naturalness”, “room-related”, “source localization”, “loudness” and “speed perception”. While the ratings showed a high degree of similarity among the ratings of the sound attributes in the different reproduction systems, there were minor differences in the speed and loudness estimations and the different perceptions of brightness stood out. A comparison of the loudness ratings in the scenes featuring electric and combustion-engine vehicles highlights the issue of reduced detection abilities with regard to the former. Full article

This paper evaluated the acoustic characteristics of electric vehicles (EVs) using both psychoacoustic and soundscape methodologies by analyzing three key psychoacoustic parameters: loudness, roughness, and sharpness. Through correlation analysis between perceived values and objective parameters, we identified specific sound sources requiring improvement, including vehicle body acoustics, wheel noise, and acceleration-related sounds. The relationship between comfort perception and acoustic parameters showed varying correlations: loudness (0.0411), roughness (2.3452), and sharpness (0.9821). Notably, the overall correlation coefficient of 0.5 suggests that psychoacoustic parameters alone cannot fully explain human comfort perception in EVs. The analysis of sound propagation revealed elevated vibration levels specifically in the driver’s seat area compared to other vehicle regions, identifying key targets for improvement. The research identified significant acoustic events at three key frequencies (50 Hz, 250 Hz, and 450 Hz), requiring in-depth analysis to determine their sources and understand their effects on the vehicle’s NVH characteristics. The study successfully validated its results by demonstrating that a combined approach using both psychoacoustic and soundscape parameters provides a more comprehensive understanding of passenger acoustic perception. This integrated methodology effectively identified specific areas needing acoustic refinement, including: frame vibration noise during rough road operation; tire-generated noise; and acceleration-related sound emissions. Full article

The concept of auditory scene analysis, popularized in scientific experiments by A. S. Bregman, the primary architect of the perceptual streaming theory, and his research team, along with more recent analyses by subsequent researchers, highlights a specific scientific gap that has not been thoroughly explored in previous studies. This article seeks to expand on this concept by introducing the author’s observation of the multivariant nature of auditory perception. This notion suggests that listeners focusing on different components of an auditory image (such as a musical piece) may perceive the same sounds but interpret them as distinct sound structures. Notably, even the same listener may perceive various structures (different mental figures) when re-listening to the same piece, depending on which musical elements they focus on. The thesis of multivariantism was examined and confirmed through the analysis of selected classical music pieces, providing concrete evidence of different interpretations of the same sound stimuli. To enhance clarity and understanding, the introduction to multivariantism was supplemented with graphic examples from the visual arts, which were then related to musical art through score excerpts from the works of composers such as C. Saint-Saëns, F. Liszt, and F. Mendelssohn Bartholdy. Full article

This paper presents a comparative analysis of simplified and high-fidelity sonic boom prediction methods to assess their applicability in the conceptual design of supersonic aircraft. The high-fidelity approach combines Computational Fluid Dynamics (CFD) for near-field shock analysis with ray-tracing and the Augmented Burgers Equation for far-field propagation through a non-uniform atmosphere, whereas the simplified Carlson method uses analytical approximations for rapid predictions. The comparison across selected climb, cruise, and descent conditions for a supersonic reference aircraft shows that the Carlson method captures general trends in sonic boom behavior, such as changes in peak overpressure and signal duration with varying Mach number and altitude. However, significant deviations are noted under realistic atmospheric conditions, highlighting limitations in the simplified model’s accuracy. Common psycho-acoustic metrics were evaluated to assess the potential annoyance on the ground. The results demonstrate that while the simplified method is effective for early-stage design assessments, the high-fidelity model is essential for precise sonic boom characterization under realistic conditions, particularly for regulatory and community impact evaluations. Full article

Background: Children with developmental coordination disorder (DCD) exhibit reduced interlimb coordination compared to typically developing children (TDC) during complex tasks like running, which requires dynamic postural control. However, the extent of interlimb coordination difficulties in DCD during tasks that demand minimal dynamic balance, such as self-paced and externally auditory-paced tasks, remains unclear. This study aimed to compare interlimb coordination and auditory–motor synchronization between children with DCD and TDC during a seated antiphase coordination task of the lower limbs, which has minimal postural control requirements. Methods: Twenty-one children with DCD and 22 TDC performed an antiphase knee flexion and extension task while seated, in three conditions (baseline silence, metronome discrete, and metronome continuous), for three minutes. The interlimb coordination, synchronization, and spatiotemporal movement parameters were analyzed using a mixed model analysis; Results: Children with DCD displayed less coordinated interlimb movements compared to TDC (p = 0.0140), which was the result of the greater variability in coordinating antiphase knee flexion–extension movements (p < 0.0001). No group differences in spatiotemporal movement parameters were observed. Children with DCD, compared to TDC, had a lower synchronization consistency to metronomes (p = 0.0155). Discrete metronomes enhanced interlimb coordination compared to the baseline silence condition (p = 0.0046); Conclusions: The study highlights an inferior interlimb coordination and auditory–motor synchronization in children with DCD compared to TDC. Implementing metronomes with a discrete temporal structure improved the interlimb coordination of both groups during the used fundamental seated interlimb coordination task, supporting theorical frameworks of event-based timing. Full article

This paper reconstructs the sound of 19th-century alphorns based on contemporary written descriptions, which allows for a better understanding of literature and compositions that quoted and imitated the alphorn throughout the 19th century. In the absence of sound recordings, historical documents and literary sources provide valuable insights into the timbre of these traditional Alpine instruments. The research examines descriptions from 19th-century texts, comparing them with modern understandings of musical timbre. By analyzing the language used to describe the alphorn’s sound, the study identifies recurring descriptors and contextualizes them within the broader acoustic environment, including the influence of natural sounds like waterfalls and echoes. Historical sources reveal a complex perception of the alphorn’s timbre, described in terms of its resemblance to muted trumpets and a blend of brass and woodwind qualities. Authors such as Hermann Alexander von Berlepsch and François-Joseph Fétis provided detailed accounts, noting contrasting characteristics like “rough”, “soft”, “sharp”, and “melodious”, which varied with the listener’s distance from the instrument. These descriptions highlight the alphorn’s unique sound profile, distinct from modern perceptions that emphasize a warmer, fuller timbre. The findings underscore the importance of considering ecological and psychoacoustic contexts in the study of historical musical instruments. Full article