Vibration Speaker Research Articles

Feasibility of a new noise prediction method using vibration speakers to verification of interior noise reduction effects

To effectively reduce interior noise in railway vehicles, the effect of new noise-reduction measures must be pre-estimated before their implementation. We are developing a new method for interior noise prediction, using a vibration speaker to estimate the multiple-input multiple-output transfer functions from the acceleration of interior panels to the sound pressures at the evaluation points. In this paper, we verify the possibility and report on the feasibility of predicting the effect of interior noise reduction in railway vehicles when the vibrations of interior panels are reduced to improve quietness in the cabin. First, we conducted a vibration test using a vibration speaker on a Shinkansen test car to estimate the transfer functions from each interior panel to the noise evaluation point. Then, we conducted another vibration test to simulate the running condition, aiming to reproduce the interior noise. Finally, by assuming that the vibrations of the interior panels are reduced in the second vibration test, we show the feasibility of the proposed method to verify the noise-reduction effect by using it to predict the interior noise with vibration-reduction measures.

A&I, a Suite for Piano, Android Device and Vibration Speaker

Abstract As part of an ongoing work with speakers that use uncommon technologies to project sound, the author considers here the vibration speaker, a kind of transducer that coaxes a surface to vibrate by direct contact. Presenting pros and cons of vibration speakers, the author illustrates a piano suite that uses an application expressly built for Android as an interface between the sound produced in, on, or with the piano and the speaker: The sound is captured by the Android device, processed by the application, sent via Bluetooth to the speaker sitting on the piano soundboard, and eventually thereby amplified. This relatively simple system allows for a large array of timbral possibilities and unconventional ways of playing the piano.

Nonlinear Piezoelectric Energy Harvester: Experimental Output Power Mapping

In this paper, the output power map of a nonlinear energy harvester (PEH) made of a console beam and the membrane of a resonant vibration speaker is analyzed experimentally. The PEH uses two large piezoelectric patches (PZT-5H) bonded into a parallel bimorph configuration. The nonlinear response of the deformable structure provides a wider bandwidth in which power can be harvested, compensating for the mistuning effect of linear counterparts. The nonlinear response of the proposed PEH is analyzed from the perspective of its electrical performance. The proposed experimental method provides novelty by measuring the effects produced by the nonlinearity of the deformable structure on the output power map. The objective of this analysis is to optimize the size of the PZT patch in relation to the size of the console beam, providing experimental support for the design. The presentation of the most significant experimental results of a nonlinear PEH, followed by experimental mapping of the output power, ensured that the proposed objective was achieved. The accuracy of the experimental results was determined by the high degree of automation in the experimental setup, assisted by advanced data processing.

Leafcutter ants adjust foraging behaviours when exposed to noise disturbance.

We investigate the impact of anthropogenic noise on the foraging efficiency of leafcutter ants (Acromyrmex octospinosus) in a controlled laboratory experiment. Anthropogenic noise is a widespread, pervasive and increasing environmental pollutant and its negative impacts on animal fitness and behaviour have been well documented. Much of this evidence has come from studies concerning vertebrate species with very little evidence for terrestrial invertebrates, especially social living invertebrates. We compare movement speed, forage fragment size, and colony activity levels of ants exposed to intermittent elevated noise and in ambient noise conditions. We use intermittent and temporally unpredictable bursts of white noise produced from a vibration speaker to create the elevated noise profile. Ant movement speed increased under elevated noise conditions when travelling to collect forage material and when returning to the colony nest. The size of individually measured foraged material was significantly reduced under elevated noise conditions. Colony activity, the number of ants moving along the forage route, was not affected by elevated noise and was consistent throughout the foraging events. Increased foraging speed and smaller forage fragments suggests that the ants had to make more foraging trips over an extended period, which is likely to affect energy expenditure and increases exposure to predators. This is likely to have significant fitness impacts for the colony over time.

Cartilage Conduction Hearing and Its Clinical Application.

Cartilage conduction (CC) is a form of conduction that allows a relatively loud sound to be audible when a transducer is placed on the aural cartilage. The CC transmission mechanism has gradually been elucidated, allowing for the development of CC hearing aids (CC-HAs), which are clinically available in Japan. However, CC is still not fully understood. This review summarizes previous CC reports to facilitate its understanding. Concerning the transmission mechanism, the sound pressure level in the ear canal was found to increase when the transducer was attached to the aural cartilage, compared to an unattached condition. Further, inserting an earplug and injecting water into the ear canal shifted the CC threshold, indicating the considerable influence of cartilage–air conduction on the transmission. In CC, the aural cartilage resembles the movable plate of a vibration speaker. This unique transduction mechanism is responsible for the CC characteristics. In terms of clinical applications, CC-HAs are a good option for patients with aural atresia, despite inferior signal transmission compared to bone conduction in bony atretic ears. The advantages of CC, namely comfort, stable fixation, esthetics, and non-invasiveness, facilitate its clinical use.

Development of landslide sign detection using longitudinal vibration mode of elastic bar is subjected to ground soil elastic force

In this paper, the landslide sign detection sensing method is proposed. First, the requirement definition is conducted based on survey result of conventional detection technology. As the result, importance of internal state estimation of soil status is pointed out. Furthermore, active sensing method based on longitudinal vibration mode of elastic bar subjected to ground soil elastic force is proposed in order to realize the internal state estimation of soil status. Moreover, the prototyping of active sensing system of elastic bar is conducted. The system is composed from elastic bar, vibration speaker, acceleration sensor and data logger. The laboratory experiment of vibration mode visualization is conducted in order to decision of vibration diagnosis mode. As the result, the vibration diagnosis mode is selected. Mode shape of the vibration diagnosis mode is derived from longitudinal mode of elastic bar.

Effect of Input Waveform to Vibration Speaker on Sound Quality of Electric Artificial Voice

Effect of Input Waveform to Vibration Speaker on Sound Quality of Electric Artificial Voice

Integration of High-Resolution Laser Displacement Sensors and 3D Printing for Structural Health Monitoring.

This paper presents a novel experimental design for complex structural health monitoring (SHM) studies achieved by integrating 3D printing technologies, high-resolution laser displacement sensors, and multiscale entropy SHM theory. A seven-story structure with a variety of composite bracing systems was constructed using a dual-material 3D printer. A wireless Bluetooth vibration speaker was used to excite the ground floor of the structure, and high-resolution laser displacement sensors (1-μm resolution) were used to monitor the displacement history on different floors. Our results showed that the multiscale entropy SHM method could detect damage on the 3D-printed structures. The results of this study demonstrate that integrating 3D printing technologies and high-resolution laser displacement sensors enables the design of cheap, fast processing, complex, small-scale civil structures for future SHM studies. The novel experimental design proposed in this study provides a suitable platform for investigating the validity and sensitivity of SHM in different composite structures and damage conditions for real life applications in the future.

Evaluation of the Perceptual Characteristics of a Force Induced by Asymmetric Vibrations.

This paper describes the perceptual characteristics of a sense of a force induced by asymmetric vibration using a vibration speaker-type non-grounded haptic interface. We confirm that the vibration speaker generates a perceived force that pulls or pushes a user's hand in a particular direction when an asymmetric amplitude signal that is generated by inverting a part of a sine wave is input. In this paper, to verify the system with respect to various factors of force perception caused by asymmetric vibration, we conducted six experiments and the following results were obtained. (1) The force vector can be controlled by reversing the asymmetric waves. (2) By investigating the physical characteristics of the vibration, asymmetric vibration was confirmed. (3) The presentation of vibration in the shear direction on the finger pad is effective. (4) The point of subjective equality of the perceived force can be controlled by up to 0.43 N by changing the amplitude voltage of the input signals. (5) The minimum stimulation time required for force perception is 66.7 ms. (6) When the vibration is continuously presented for 40 to 50 s, the perceived force decreases because of adaptation. Hence, we confirmed that we can control both the direction and magnitude of the reaction force by changing the input signal of the vibration speaker.

Time reversal focusing of elastic waves in plates for an educational demonstration.

The purpose of this research is to develop a visual demonstration of time reversal focusing of vibrations in a thin plate. Various plate materials are tested to provide optimal conditions for time reversal focusing. Specifically, the reverberation time in each plate and the vibration coupling efficiency from a shaker to the plate are quantified to illustrate why a given plate provides the best spatially confined focus as well as the highest focal amplitude possible. A single vibration speaker and a scanning laser Doppler vibrometer (SLDV) are used to provide the time reversal focusing. Table salt is sprinkled onto the plate surface to allow visualization of the high amplitude, spatially localized time reversal focus; the salt is thrown upward only at the focal position. Spatial mapping of the vibration focusing on the plate using the SLDV is correlated to the visual salt jumping demonstration. The time reversal focusing is also used to knock over an object when the object is placed at the focal position; some discussion of optimal objects to use for this demonstration are given.

“Knocked Over!”: A visual demonstration of time reversal focusing using bending waves in a thin plate

The purpose of this research is to develop a visual demonstration of time reversal focusing in a thin plate to be used as a teaching tool. This presentation will discuss the various plate materials tested to provide the optimal conditions for time reversal focusing. Specifically, the reverberation time in each plate and the sensitivity of the source of vibrations are quantified to provide the best spatially confined focus as well as the highest focal amplitude possible. A vibration speaker and a scanning laser Doppler vibrometer (SLDV) are used to provide the time reversal focusing. A series of objects are placed on the plate in an attempt to knock over objects near the focal location and not elsewhere. Spatial mapping of the plate vibration using the SLDV will be shown to illustrate why some objects fall and others do not.

VIBRATION SPEAKER AND A PORTABLE ELECTRONIC DEVICE COMPRISING THE VIBRATION SPEAKER

A vibration speaker for a portable electronic device is disclosed herein. The vibration speaker comprises a case. A loudspeaker member for generating a sound is contained in the case. The loudspeaker member comprises a frame, a magnet, a voice coil and a membrane. The voice coil is operable to generate a movement of the membrane vertically up and down when an electric current is applied to the voice coil and a magnetic field is formed by interaction between the voice coil and the magnet. The vibration speaker additionally comprises a vibration coil for generating a vibration.The vibration coil is positioned in relation to the magnet of the loudspeaker member such that the vibration coil is operable to generate a movement of the entire loudspeaker member vertically up and down when an electric current is applied to the vibration coil and a magnetic field is formed by interaction between the vibration coil and the magnet. Metal springs may be positioned to elastically support between the loudspeaker member and the case.

Resonance frequency correction method and vibration speaker

A method of correcting a resonance frequency in a vibration speaker generating acoustic sound and vibration includes adjusting the actual resonance frequency to a higher resonance frequency by limiting a predetermined portion of an elastic member installed in a case to an inside of the case to increase the resonance frequency when the actual resonance frequency is not identical to nor less than the desired resonance frequency, thereby adjusting an actual resonance frequency to be identical to a desired resonance frequency, and adjusting the actual resonance frequency to a lower resonance frequency by cutting off another predetermined portion of the elastic member to decrease the resonance frequency when the actual resonance frequency is not identical to nor greater than the desired resonance frequency, thereby adjusting an actual resonance frequency to be identical to a desired resonance frequency. In the vibration speaker, the actual resonance frequency is corrected to the desired resonance frequency, thereby reducing a defect of the vibration speaker.

Vibration speaker

Vibration speaker

Vibration speaker

Vibration speaker