Pitch discrimination is better for synthetic timbre than natural musical instrument timbres, despite familiarity

Pitch discrimination is better for complex tones than for pure tones, but how more subtle differences in timbre affect pitch discrimination is not fully understood. This study compared pitch discrimination thresholds of flat-spectrum harmonic complex tones with those of natural sounds played by musical instruments of three different timbres (violin, trumpet, and flute). To investigate whether natural familiarity with sounds of particular timbres affects pitch discrimination thresholds, this study recruited musicians who were trained on one of the three instruments. We found that flautists and trumpeters could discriminate smaller differences in pitch for artificial flat-spectrum tones, despite their unfamiliar timbre, than for sounds played by musical instruments, which are regularly heard in everyday life (particularly by musicians who play those instruments). Furthermore, thresholds were no better for the instrument a musician was trained to play than for other instruments, suggesting that even extensive experience listening to and producing sounds of particular timbres does not reliably improve pitch discrimination thresholds for those timbres. The results show that timbre familiarity provides minimal improvements to auditory acuity, and physical acoustics (i.e., the presence of equal-amplitude harmonics) determine pitch-discrimination thresholds more than does experience with natural sounds and timbre-specific training.

Physical and Psychoacoustic Characteristics of Typical Noise on Construction Site: “How Does Noise Impact Construction Workers’ Experience?”

Construction noise is an integral part of urban social noise. Construction workers are more directly and significantly affected by construction noise. Therefore, the construction noise situation within construction sites, the acoustic environment experience of construction workers, and the impact of noise on them are highly worthy of attention. This research conducted a 7-month noise level (LAeq) measurement on a construction site of a reinforced concrete structure high-rise residential building in northern China. The noise conditions within the site in different spatial areas and temporal stages was analyzed. Binaural recording of 10 typical construction noises, including earthwork machinery, concrete machinery, and hand-held machinery, were performed. The physical acoustics and psychoacoustic characteristics were analyzed with the aid of a sound quality analysis software. A total of 133 construction workers performing 12 types of tasks were asked about their subjective evaluation of the typical noises and given a survey on their noise experience on the construction site. This was done to explore the acoustic environment on the construction site, the environmental experience of construction workers, the impact of noise on hearing and on-site communications, and the corresponding influencing factors. This research showed that the noise situation on construction sites is not optimistic, and the construction workers have been affected to varying degrees in terms of psychological experience, hearing ability, and on-site communications. Partial correlation analysis showed that the construction workers’ perception of noise, their hearing, and their on-site communications were affected by the noise environment, which were correlated to varying degrees with the individual’s post-specific noise, demand for on-site communications, and age, respectively. Correlation analysis and cluster analysis both showed that the annoyance caused by typical construction noise was correlated to its physical and psychoacoustic characteristics. To maintain the physical and mental health of construction workers, there is a need to improve on the fronts of site management, noise reduction, equipment and facility optimization, and occupational protection.

Research on the Optimization Design of the Acoustic Stealth Shape of a Bottom Object

This paper presents an optimal design method for the acoustic stealth shape for a bottom object with relatively lower echo strength (ES), based on the physical acoustics method (PAM) and genetic algorithm (GA). Specifically, the performance of the PAM was evaluated with acoustic scattering from a Manta-like object, using two-dimensional (2D) axisymmetric calculation method. In the optimization method, GA, the object shape represented by the Bernstein polynomial, grid topology acquired by using the MATLAB-COMSOL module and the scattering calculation are combined into a process. The optimization objective function is given as the weighting function of the ES of the bottom object with different grazing angles and frequencies. Finally, the two optimal shapes of the bottom object under different conditions are given, in which the ES and the angle detection rate after optimization are greatly reduced. This optimal method provides guidance for the lower ES shape design of bottom targets.

Ideal and Technical Filters

Chapter 3 shows how the logic of noise reduction is anchored in historical discourses on sound and technology, taking a closer look at the development, from the early nineteenth century onward, of some of the most important concepts in physical acoustics and sound engineering. First, it discusses two uncertainty principles fundamental to information theory and communication engineering, which entail compromises that limit the accuracy of any reproduction. Second, it focuses on the mathematical principles of Fourier analysis, which gave rise to the now-familiar representation of sound in terms of a “spectrum” of singular frequencies or “sine waves.” The chapter thereby explores the difference between a timeless, mathematical plane of the ideal filter in which clear, noiseless reproduction always seems possible, and a physical domain of technical filters in which transience and noise haunt every transmission. The contrast between the two, in turn, highlights the important relation between noise and time.