Field Study of the Interior Noise and Vibration of a Metro Vehicle Running on a Viaduct: A Case Study in Guangzhou

New Indicators for the Assessment and Prevention of Noise Nuisance

At present, health effects induced by prolonged noise exposure are widely studied to determine the most spread noise sources and their effects [...]

Implementation of Tension-Based Compact Necklace-Type Haptic Device Achieving Widespread Transmission of Low-Frequency Vibrations

The haptic sensation of low-frequency vibration plays a vital role in the music listening experience, but it can be enjoyed only in certain facilities and environments. Many haptic devices have been proposed to convey music audio-induced vibration for various situations. Such devices require powerful, low-frequency vibration output and transmission over a wide area. Making such devices small and user-friendly is difficult, hindering their popularity. To promote haptic devices for music listening, this paper describes a method for developing a practical device using motors and a thread and evaluates this method's effectiveness. The proposed necklace-type device is small (about 55 × 58 × 15 mm), lightweight (58.5 g), and easy to wear, making it suitable for use during everyday travel. In addition, it can transmit low-frequency (20 Hz) vibrations, whose amplitude exceeds airborne vibration in a nightclub, to a wide area across the chest and neck, with a total power consumption of approximately 2 W. Our proposed method will contribute to the development of practical and high-performance haptic devices for music listening.

Evaluating the Impact of Metro Interior Noise on Passenger Annoyance: An Experimental Study

The operation of a large-scale metro system creates problematic interior noise; the impact of this noise on passengers and drivers is a subject of increasing concern. To investigate the quantitative relationship between metro interior noise and passengers’ annoyance, this study analyzed questionnaires on passenger annoyance completed by 118 volunteers. The feedback from the questionnaire concerned eleven metro lines in Beijing. To test the interior noise levels, the volunteers were divided into two groups: A and B. The volunteers in group A took the same metro train as the testers, whereas those in group B took different trains. A total of 2080 noise annoyance samples from metro tunnel sections were collected and analyzed. Finally, the exposure-response relationship between interior noise and passenger annoyance was obtained by fitting these data with a logistic function. The results indicated that there was a significant positive correlation between the average subjective annoyance and the averaged equivalent sound pressure level. The fitting result was better for group A than for group B. For the mixed samples of two groups, the fitting result was greatly affected by the contribution of group A. To provide an acoustically comfortable environment, metro interior noise should not exceed 84–85 dB(A).

An Approach to the Definition of the Aerodynamic Comfort of Motorcycle Helmets

The aim of this work is to obtain a reliable testing methodology for the characterization of the perceived aerodynamic comfort of motorcycle helmets. Attention was paid to the rider’s perception of annoying vibrations induced by wind. In this optic, an experimental comparative campaign was performed in the wind tunnel, testing 16 helmets in two different configurations of neck stiffness. The dataset was collected within a convolutional neural network (CNN or ConvNet) of images, creating a ranking by identifying the best and the worst helmets. The results revealed that each helmet has unique aerodynamic characteristics. Depending on the ranking scale previously created, the aerodynamic comfort of each helmets can be classified within the scale.