The consumer market is demanding that the noise level of appliances be reduced to lower and lower levels to satisfy new expectations for environmental quality. This has placed a burden on the manufacturers of compressors for air conditioners and heat pumps to reduce noise radiated by their units. In order to accomplish this task, the approach has been to apply advanced signature analysis and st...

20 7 JULY 2017 • VOL 357 ISSUE 6346 sciencemag.org SCIENCE with the same goal: harnessing artificial intelligence (AI) to augment—or even replace—the role of humans in the scientific process (see graphic, p. 21). “AI-powered biotech” is how it has been described, but Zymergen’s co-founders cringe at the term. “‘AI’ sounds like a robot playing chess,” says Aaron Kimball, the company’s chief tech...

Estimation of the direction-of-arrival (DOA) of sound sources is an important step in sound field analysis. Rigid spherical microphone arrays allow the calculation of a compact spherical harmonic representation of the sound field. A basic method for analysing sound fields recorded using such arrays is steered response power (SRP) maps wherein the source DOA can be estimated as the steering dire...

A difficult problem in specifying the characteristics of electroacoustic transducers is the fact that the sound pressure level measured in a standard coupler or artificial ear is not the same as that at the eardrum. A related problem is encountered in specifying the overall gain of a hearing aid. This latter problem is especially difficult because of the complexity of the acoustic coupling betw...

A simplified physical model, which described the generation of sound by a Helmholtz resonator upon flow excitation at its neck, was developed in the present investigation to study the drop in sound power transmission loss across such a resonator mounted on the wall of a duct conveying a low Mach number mean flow. Experiments were derived to validate the model. Mitigation methods derived accordi...

In this study, four channels' heart sounds of normal persons and patients with coronary artery disease (CAD) were detected by a highly sensitive sound sensors array placed on special positions of body's thorax, the acquired signals were analyzed using wavelet transform and neural networks. Wavelet transform is a highly applicable method to separate the complicated heart sounds into various freq...

The purpose of this article is to study the heat transfer characteristics of a voice-coil and permanent magnet for a speaker using nano-sized ferrofluid. In order to investigate the temperature characteristics of the speaker, the speaker power ratings, ambient temperatures of the test chamber, chamber sizes and input signals were tested. As a result, the temperatures of the voice-coil and magne...

background: one of the most widely used equipments in harvesting hay and grains are four wheel mowers. the aim of the present study was to determine the levels of noise exposure in drivers and bystanders in different states, speeds and gear of four wheel mowers (bcs model 622).   methods: the iso 5131 and iso 6814 standards were used to assess noise exposure in drivers and bystanders, respectiv...

Farfield beamforming is a powerful tool for identifying spatially distributed noise sources. The technique yields an image of the relative sound levels within the measurement aperture. The latest version of the beamforming software is now able to estimate the total power within its measurement aperture. In this work, the noise sources on three types of construction equipment are imaged with a b...

We analyze the implications of having a divergent speed of sound in k-essence cosmological models. We first study a known theory of that kind, for which the Lagrangian density depends linearly on the time derivative of the k-field. We show that consistency requires that the potential of the k-field be of the inverse square form. Then, we review the known result that the corresponding power-law ...