Acoustics & Audio Technology News

Researchers have discovered a nanoscale motor in the human ear that mechanically amplifies sound. In effect, the ear utilizes a mechanical amplifier since it "uses electrical power to do mechanical amplifications," says Professor Richard Rabbitt, University of Utah College of Engineering. As they move to and fro, hair-like tubes magnify quiet sounds in what is described as the "flexoelectric effect."

UK scientists believe they have found the solution to "red tides" by subjecting the algae to ultrasonic blasts. It is postulated that ultrasound pressure waves destroy buoyancy cells (heterocycts) by bringing them to a resonant frequency, which causes them to burst releasing buoyant nitrogen bubbles. Algae sink and then die without sunlight.

Ultrasound images with improved depth resolution could allow doctors to correct congenital malformations within the womb or operate on a beating heart. What's needed is a 2D array of minuscule transducers to produce highly detailed 3D images in real time. Fortunately, bonding silicon and silicon-on-insulator wafers (with through-silicon vias) using MEMS fabrication methods can produce just-the-right-size capacitive micro-machined ultrasonic transducers.

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Acoustic materials often come to the (noise) rescue in hospitals, schools, and other buildings. A case in point is a composite flooring material recently installed in a UK academy. The 3.7 mm material delivers a >19 dB level of sound insulation via an integrated foam layer. It also incorporates a transparent 0.65 mm aluminum-oxide-filled PVC wear layer to prevent slipping.

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Why not create a lowest-cost plus lowest-power digital signal processor with Ethernet connectivity? TI did it so that audio products can get to market faster and then later be software-upgraded as the product evolves. Current applications include audio foot pedals, conference phones, electrocardiography, oscilloscopes, programmable automation, power protection, and test/measurement systems.

Combining real-time signal processing and a multi-sensor array, engineers will be able to more quickly find problems within sewer systems. Compared to the previous two to four hours needed to find blockage and other damage, a new acoustic monitoring system being perfected by Professor Horoshenkov, Bradford University, can check the same 100 m of pipe in tens of minutes.

Security for mobile devices can be a challenge for any enterprise given the wide range of different devices and platforms for different employees with different job functions. Nevertheless, a centralized management approach is paramount. Fortunately, best practices are being created, as this TechNewsWorld article explores.

Chinese researchers have come up with a way to boost the voice quality of mobile speakerphones and laptops in noisy environments. The application combines MEMS microphone arrays with a time-reversal method. The latter allows the original signal to be recovered. The end results include clearer voice with an improved signal-to-noise ratio.

Excessive noise from road traffic is not only annoying for many, but increases heart attack risk. As noted in Echoes (p. 6 lower right), the Acoustical Society of America's quarterly newsletter, an Epidemiology paper concluded that residents exposed to >50 dB traffic noise have a 40% higher risk of myocardial infarction than those living in quieter neighborhoods.

Based on groundbreaking acoustic analysis, researchers report that a hyena's laugh is more like "fighting words." The giggles they report are actually linked to frustration, for example, in the context of fighting for food or other social challenge. After measuring amplitude, frequency, and length of the sounds, it was concluded that pitch (frequency) is a function of social standing. Video bytes.

Green, but Acoustically Mean Buildings

As it turns out many of the latest energy-efficient buildings — even LEED-rated ones — are too noisy for many people. How is it at your workplace/office?