A Pilot Study of Pedestrians with Visual Impairments Detecting Traffic Gaps and Surges Containing Hybrid Vehicles

The increasing number of hybrid and quiet internal combustion engine vehicles may impact the travel abilities of pedestrians who are blind. Pedestrians who rely on auditory cues for structuring their travel may face challenges in making crossing decisions in the presence of quiet vehicles. This article describes results of initial studies looking at the crossing decisions of pedestrians who are blind at an uncontrolled crossing (no traffic control) and a light controlled intersection. The presence of hybrid vehicles was a factor in each situation. At the uncontrolled crossing, Toyota hybrids were most difficult to detect but crossing decisions were made more often in small gaps ended by a Honda hybrid. These effects were seen only at speed under 20 mph. At the light controlled intersection, parallel surges of traffic were most difficult to detect when made up only of a Ford Escape hybrid. Results suggest that more controlled studies of vehicle characteristics impacting crossing decisions of pedestrians who are blind are warranted

Minimizing the radiated sound power from vibrating plates by using in-plane functionally graded materials

This paper presents a method for decreasing sound radiation from vibrating plates. The method uses Functionally Graded Materials (FGM) for building the plates instead of isotropic material. The graded pattern of material composition is characterized within the in-plane directions based on a two-dimensional trigonometric law. In the proposed method, the finite element method (FEM) is utilized for estimating the dynamic response of the plates. Then, the Lumped Parameter Model (LPM) is used for calculating sound radiation power. A genetic algorithm is applied as an optimization tool for determining the best distribution of the FGM. The efficacy of the proposed method is demonstrated by three design problems; minimizing the radiated sound from vibrating FGM plate at a particular excitation frequency, over a frequency band, and at a particular natural frequency. The design problems show that a considerable decrease of sound power can be accomplished with the optimal design of FGM plates in comparison with the isotropic plates

Optimization of Natural Frequencies and Sound Power of Beams Using Functionally Graded Material

This paper presents a design method to optimize the material distribution of functionally graded beams with respect to some vibration and acoustic properties. The change of the material distribution through the beam length alters the stiffness and the mass of the beam. This can be used to alter a specific beam natural frequency. It can also be used to reduce the sound power radiated from the vibrating beam. Two novel volume fraction laws are used to describe the material volume distributions through the length of the FGM beam. The proposed method couples the finite element method (for the modal and harmonic analysis), Lumped Parameter Model (for calculating the power of sound radiation), and an optimization technique based on Genetic Algorithm. As a demonstration of this technique, the optimization procedure is applied to maximize the fundamental frequency of FGM cantilever and clamped beams and to minimize the sound radiation from vibrating clamped FGM beam at a specific frequency

PlosOne_Data_Job

Data were collected from audio recordings made in the field in Kalamazoo County, MI during the summer of 2013 using Wildlife Acoustics Song Meter 2. Values were extracted from recordings using custom script written in MatLab, as well as ArcMap by ESRI. 'Subset' refers to the number of microphones used to make maps, 'Additional Microphones' refer to the presence (Y) or absence (N) of additional flanking microphones, 'PlaybackLocation' refers to the location of the noise playback either within (Inside) or at the edge of arrays (Outside), and 'SPL' refers to sound pressure level in decibels (dB)

Uncovering Spatial Variation in Acoustic Environments Using Sound Mapping

<div><p>Animals select and use habitats based on environmental features relevant to their ecology and behavior. For animals that use acoustic communication, the sound environment itself may be a critical feature, yet acoustic characteristics are not commonly measured when describing habitats and as a result, how habitats vary acoustically over space and time is poorly known. Such considerations are timely, given worldwide increases in anthropogenic noise combined with rapidly accumulating evidence that noise hampers the ability of animals to detect and interpret natural sounds. Here, we used microphone arrays to record the sound environment in three terrestrial habitats (forest, prairie, and urban) under ambient conditions and during experimental noise introductions. We mapped sound pressure levels (SPLs) over spatial scales relevant to diverse taxa to explore spatial variation in acoustic habitats and to evaluate the number of microphones needed within arrays to capture this variation under both ambient and noisy conditions. Even at small spatial scales and over relatively short time spans, SPLs varied considerably, especially in forest and urban habitats, suggesting that quantifying and mapping acoustic features could improve habitat descriptions. Subset maps based on input from 4, 8, 12 and 16 microphones differed slightly (< 2 dBA/pixel) from those based on full arrays of 24 microphones under ambient conditions across habitats. Map differences were more pronounced with noise introductions, particularly in forests; maps made from only 4-microphones differed more (> 4 dBA/pixel) from full maps than the remaining subset maps, but maps with input from eight microphones resulted in smaller differences. Thus, acoustic environments varied over small spatial scales and variation could be mapped with input from 4–8 microphones. Mapping sound in different environments will improve understanding of acoustic environments and allow us to explore the influence of spatial variation in sound on animal ecology and behavior.</p></div

Results of a four-way ANOVA exploring influences on map differences during noise introductions.

<p>Results of a four-way ANOVA exploring influences on map differences during noise introductions.</p