EAGER: Acoustic Diode as Architectural Material (ADAM)

University Of Pittsburgh, Pittsburgh PA

Investigators

Abstract

Acoustic noise is the slyest form of pollution because its effects on the human health are underestimated. Exposure to noise may hamper the nervous system, trigger stress and sleep disorder, and may cause heart problems and high blood pressure. People are exposed to noise almost anywhere. For this reason engineers and architects strive to create effective and fine solutions to mitigate indoor-generated noise in order to enhance the comfort of the occupants, improve personnel efficiency in the workplace, guarantee privacy, and to provide distraction-free spaces. With this societal problem in mind, this EArly-concept Grant for Exploratory Research (EAGER) project will explore a new architectural system, based on the concept of acoustic diode acting as a sound barrier. The outcome of this EAGER will enable to carry out a comprehensive study that will address a societal issue that impacts a large fraction of the human population. Additionally, the project will be of interest for architectural and structural engineering, and will be impactful in many ways including the: (1) the cross-pollination of a few different disciplines such as acoustics, nonlinear dynamics, and architectural engineering; (2) supervision of a diverse pool of students with skills in computation and experimentation; (3) integration of the research findings into a multidisciplinary education program to engage senior undergraduates, professional M.S. and graduate students; (4) outreach and dissemination activities to inform the academic community, professional engineers, professionals and some general young audience of the economic and societal impacts of designing better acoustic barriers using the novel concepts of acoustic metamaterials. Like their electrical counterpart, acoustic diodes offer low resistance to sound in one direction and high resistance in the opposite direction. In other words, acoustic diodes offer the opportunity to forbid sound transmission along one direction. The hypothesis of this research is that a diode, embedded in the novel architectural material, can be scaled at multiple lengths to shield indoor noise and eventually transit-generated noise. The new noise barrier will be composed of three elements: a membrane, an acoustic diode made of 1-D chains of spherical particles with intruders, and a plate. The idea is that the noise to be shielded reaches the wall and is converted into vibration in the membrane. This vibration triggers the formation and propagation of nonlinear solitary waves along the diode where they are trapped and decay by the effect of multiple reflections. The merit of this project lies in the investigation of the fundamental physical concepts that will lead to the development of a novel architectural noise barrier.