Sound Localization through Multi-Scattering and Gradient-Based Optimization

A gradient-based optimization (GBO) method is presented for acoustic lens design and sound localization. GBO uses a semi-analytical optimization combined with the principle of acoustic reciprocity. The idea differs from earlier inverse designs that use topology optimization tools and generic algorithms. We first derive a formula for the gradients of the pressure at the focal point with respect to positions of a set of cylindrical scatterers. The analytic form of the gradients enhances modeling capability when combined with optimization algorithms and parallel computing. The GBO algorithm maximizes the sound amplification at the focal point and enhances the sound localization by evaluating pressure derivatives with respect to the cylinder positions and then perturbatively optimizing the position of each cylinder in the lens while incorporating multiple scattering between the cylindrical scatterers. The results of the GBO of the uni- and multi-directional broadband acoustic lens designs are presented including several performance measures for the frequency dependence and the incidence angle. A multi-directional broadband acoustic lens is designed to localize the sound and to focus acoustic incident waves received from multiple directions onto a predetermined localization region or focal point. The method is illustrated for configurations of sound hard and sound soft cylinders as well as clusters of elastic thin shells in water.

Multi-Zone Active Noise Control Strategy for the Scattered Sound Control of an Infinite Rigid Cylinder

Active noise control can be used to reduce the scattered sound of a reflecting object to make it invisible to incident acoustic waves. For the multi-zone active noise control of scattered sound from an infinite rigid cylinder, an active control strategy is proposed that combines the least absolute shrinkage and selection operator (LASSO) algorithm with constraint points and regularized least squares (RLS) algorithm. The proposed control strategy is used to promote control performance through optimizing the secondary loudspeaker placement of an active noise control system. Compared with the RLS algorithm employing the uniformly placed loudspeakers and the traditional LASSO algorithm, the proposed strategy has better reduction performance both in the forward-scattered and backward-scattered sound target areas, and there is less sound amplification in the far field. From 400 Hz–1100 Hz, the proposed strategy provides a 5 dB–16 dB reduction performance advantage in the target area compared to the RLS algorithm employing uniformly placed loudspeakers.

Instructional Plans: Grades K–2

Chapter 5 presents three instructional plans that are geared toward grades K–2. Instructional plans consist of planning necessities, standard alignment, alignment to philosophies approached in earlier chapters, as well as instructional procedures and assessments. Adaptations for other grade-level bands as well as potential extensions are available for each plan. This chapter includes the following instructional plans: Shapes of Electric Guitars, Sound Amplification and Speaker Building, and Measuring Length and Pitch. In Shapes of Electric Guitars, students will design guitar bodies and perform on them using available technology. In Sound Amplification, students will analyze and experiment with sound waves, eventually building their own small speaker. In Measuring Length and Pitch, students will measure pitched tubes to determine the mathematical relationship between pitches.

Subtype specific responses in hKv7.4 and hKv7.5 channels to polyunsaturated fatty acids

The KV7.4 and KV7.5 subtypes of voltage-gated potassium channels are expressed in several tissues where they play a role in physiological processes such as sound amplification in the cochlea and adjusting vascular smooth muscle tone. Therefore, the mechanisms that regulate KV7.4 and KV7.5 channel function are of interest. Here, we study the effect of polyunsaturated fatty acids (PUFAs) on human KV7.4 and KV7.5 channels expressed in Xenopus oocytes. We report that KV7.5 is activated by PUFAs, which shift the V50 of the conductance versus voltage (G(V)) curve towards more negative voltages. This response depends on the charge of the head group as an uncharged PUFA analogue has no effect and a positively charged PUFA analogue induces positive V50 shifts. In contrast, we find that the KV7.4 channel is inhibited by PUFAs, which shift V50 towards more positive voltages. No effect on V50 of KV7.4 is observed by an uncharged or a positively charged PUFA analogue. Oocytes co-expressing KV7.4 and KV7.5 display an intermediate response to PUFAs. Altogether, the KV7.5 channel's response to PUFAs is like that previously observed in KV7.1-7.3 channels, whereas the KV7.4 channel response is opposite, revealing subtype specific responses to PUFAs.

An Acoustic Way to Support Japanese Children’s Effective English Learning in School Classrooms

In this paper, the importance of implementing good acoustic conditions in classrooms using sound amplification systems is investigated to support more effective English education for elementary school children. To date, the failure of educating English as a second language at Japanese schools has been demonstrated by poor English conversation ability of those who completed a compulsory six-year English language course at Japanese junior-high and high schools (age 12–18). To amend the situation, teaching English became compulsory at grade three (age 8–9) and above at most Japanese elementary schools in the 2020 academic year. We conducted acoustic measurements of two types of sound amplification systems, a pair of PC loudspeakers and another with a loudspeaker array, in a typical classroom at an elementary school in Japan. We also analysed English listening test results of 216 Japanese native children (age 11–12) who were learning English in their usual classes in Japan, to compare the effects of those two systems. Results of logistic regression analysis adjusted by the discrimination difficulty of word pairs demonstrated the statistically significant association between correct answer rate of the English tests and classroom acoustic factors. Although, on average, upgrading the sound amplification system had positive effects on the correct answer rate, it also had a negative impact when the word pairs had English phoneme contrasts that do not appear in Japanese phoneme structure. Combined with the acoustic measurements’ results, it was also revealed that heterogeneous sound fields that depend on seat positions could be compensated using sound amplification systems with loudspeaker arrays. Our findings suggest that improvement of both acoustic quality and teaching methods is required for children to acquire English communication skills effectively in their classroom.

Hearing more to Hear less: a scoping review of hearing aids for tinnitus relief

BackgroundTinnitus, the perception of a sound in absence of an external auditory source, can significantly impact ones’ quality of life. As tinnitus is often associated with hearing loss, hearing aids have been proposed for tinnitus relief in literature for more than 70 years. While there is a long history of clinical work and research on this topic, there is a need for recent literature to be reviewed and guide decision making in tinnitus management.ObjectiveThe aim of this scoping review is to provide an update of the available evidence on hearing aids for tinnitus, focusing on the effect of sound amplification, to draw conclusions for clinical practice and identify gaps in the field. A consultation exercise was included to discuss current issues that practitioners and carers themselves face but remain under-researched.DesignThis scoping review was conducted based on the six-stage framework of Arksey et al. (2005). Studies were included if they investigated hearing aids for tinnitus and were published after 2011. Databases of PubMed and Scopus were explored on the 16th of November 2020. The search was limited to English manuscripts. A total of 28 primary research studies were selected.ResultsPositive results of hearing aids for tinnitus relief were shown by 68 % of the studies, whereas 14 % demonstrated no change in tinnitus perception. As the quality of the evidence across studies was variable, no consensus can be reached regarding the use of hearing aids as a treatment for tinnitus. Nevertheless, recent studies were more likely to focus on optimizing the effect of hearing aids and better predicting which tinnitus patients benefit from hearing aids. The experts stated that the findings were in agreement with their view on the scientific evidence and they emphasized the importance of reaching consensus.ConclusionsThe majority of the studies supported the use of hearing aids for tinnitus relief. Hence, there was some scientific support for it, but the quality of evidence was questioned. Stronger methodology in future studies is needed to reach consensus and support clinical guidelines development.

Assembling cheap, high-performance microphones for recording terrestrial wildlife: the Sonitor system

Passive acoustic monitoring of wildlife requires sound recording systems. Several cheap, high-performance, or open-source solutions currently exist for recording soundscapes, but all rely on commercial microphones. Commercial microphones are relatively expensive, specialized for particular taxa, and often have incomplete technical specifications. We designed Sonitor, an open-source microphone system to address all needs of ecologists that sample terrestrial wildlife acoustically. We evaluated the cost and durability of our system and measured trade-offs that are seldom acknowledged but which universally limit microphones' functions: weatherproofing versus sound attenuation, windproofing versus transmission loss after rain, signal loss in long cables, and analog sound amplification versus directivity with acoustic horns. We propose five microphone configurations suiting different budgets (from 8 to 33 EUR per unit), and fulfilling different sound quality and flexibility requirements. The Sonitor system consists of sturdy acoustic sensors that cover the entire sound frequency spectrum of sonant terrestrial wildlife at a fraction of the cost of commercial microphones.