Structure-Borne Sound Research Articles

Detection of Total Hip Replacement Loosening Based on Structure-Borne Sound: Influence of the Position of the Sensor on the Hip Stem.

Accurate detection of implant loosening is crucial for early intervention in total hip replacements, but current imaging methods lack sensitivity and specificity. Vibration methods, already successful in dentistry, represent a promising approach. In order to detect loosening of the total hip replacement, excitation and measurement should be performed intracorporeally to minimize the influence of soft tissue on damping of the signals. However, only implants with a single sensor intracorporeally integrated into the implant for detecting vibrations have been presented in the literature. Considering different mode shapes, the sensor's position on the implant is assumed to influence the signals. In the work at hand, the influence of the position of the sensor on the recording of the vibrations on the implant was investigated. For this purpose, a simplified test setup was created with a titanium rod implanted in a cylinder of artificial cancellous bone. Mechanical stimulation via an exciter attached to the rod was recorded by three accelerometers at varying positions along the titanium rod. Three states of peri-implant loosening within the bone stock were simulated by extracting the bone material around the titanium rod, and different markers were analyzed to distinguish between these states of loosening. In addition, a modal analysis was performed using the finite element method to analyze the mode shapes. Distinct differences in the signals recorded by the acceleration sensors within defects highlight the influence of sensor position on mode detection and natural frequencies. Thus, using multiple sensors could be advantageous in accurately detecting all modes and determining the implant loosening state more precisely.

Experimental studies on the effect of ceiling materials on the sound environment of underpass concourse using the station simulator

Sound environments in railway stations are often noisy because of sound-reflective materials and many noise sources. Especially in underpass concourses, structure-borne sounds are radiated from the ceiling due to vibrations when trains pass by. This results in a high noise level, which often interferes with listening to the announcements. In this study, to examine interior materials that effectively reduce such noise in railway stations, the following measurements and laboratory experiments were carried out: 1) Field measurements of vibrations of the ceiling and environmental sound in stations in Tokyo. 2) Reproduction of vibrations and sounds in the station simulator (full-scale mock-up of a station building), under the four different types of ceilings. 3) Auditory tests to evaluate the noisiness of train passing sounds and environmental sounds, using reproduced sounds in the station simulator as test sounds. As a result, the ceiling with damping material was effective for structure-borne sound, while the ceiling with porous sound-absorbing material was effective for air-borne sound. This result suggests that it is important to consider the placement of ceiling materials according to the noise situations.

Watching Your Phone's Back

Gesture recognition on the back surface of mobile phone, not limited to the touch screen, is an enabling Human-Computer Interaction (HCI) mechanism which enriches the user interaction experiences. However, there are two main limitations in the existing Back-of-Device (BoD) gesture recognition systems. They can only handle coarse-grained gesture recognition such as tap detection and cannot avoid the air-borne propagation suffering from the interference in the air. In this paper, we propose StruGesture, a fine-grained gesture recognition system using the back of mobile phones with ultrasonic signals. The key technique is to use the structure-borne sounds (i.e., sound propagation via structure of the device) to recognize sliding gestures on the back of mobile phones. StruGesture can fully extract the structure-borne component from the hybrid Channel Impulse Response (CIR) based on Peak Selection Algorithm. We develop a deep adversarial learning architecture to learn the gesture-specific representation for robust and effective recognition. Extensive experiments are designed to evaluate the robustness over nine deployment scenarios. The results show that StruGesture outperforms the competitive state-of-the-art classifiers by achieving an average recognition accuracy of 99.5% over 10 gestures.

Perception of Structure-Borne Sound in Buildings in Context of Vibration Comfort of Human in the Buildings

Structure-borne noise is an extremely complex issue considering comfort of room users. The purpose of this work is to focus on the impact of vibration on humans in building together with the structure-borne noise generated by vibrating partitions of the room. Radiation of noise from vibrating partitions creates structure-borne noise, which is an additional stimulus, in addition to mechanical vibration of the floor. This means it may result in reduced comfort. Based on the review of current knowledge, it can be concluded that the perception of two simultaneous stimuli causes more annoyance than considering stimuli separately. Considering the fact that vibrations and structure-borne noise, due to the mechanics of the phenomenon, usually occur together, it is necessary to analyse the existing comfort assessment criteria. In addition, validity of given existing criteria has to be verified in the light of the phenomenon of structure-borne noise. This task was carried out using models with different approaches to the phenomenon. Basing on the given values of accelerations or velocities of floor two models were created. First model consists of single vibrating plate, with known vibration velocity. Vibrating plate radiates sound inside the modelled room. Sound pressure level was estimated using simple theoretical formulas present in literature. Second model is prepared as 3D FEM model with shell elements surrounding the room. Air was modelled inside room with 3D elements. Sound pressure level was calculated from simulations. The work aimed at determining the legitimacy of the assumption in the Polish standard PN-B-02171:2017 of mechanical vibration perception threshold and the admissible values determining mechanical vibrations.

An engineering method to measure structure-borne sounds transmitted through the building partitions

An engineering method to measure structure-borne sounds transmitted through the building partitions

Optimized Mounting Positions for Vibratory Machines in Buildings Based on Structure-Borne Sound Power Transmission and Machine Stability

Optimized mounting positions for isolated vibratory machines in buildings require a minimum transmission of structure-borne sound power from the machine to the floor structure and relative stability of the isolated machine. Previous work by Mak and co-investigators has indicated the importance of using structure-borne sound power to assess vibration isolation and to select the best mounting positions by considering the structure-borne sound power transmission. This paper is a first attempt to utilize both the structure-borne sound power transmission and the rotational velocity (or the stability) of the machine to select the optimized mounting positions for an isolated vibratory machine. The results reveal that a vibratory machine should be symmetrically installed on diagonal lines of the receiving floor structure.

An engineering method to measure the impact sound reduction due to soft coverings on heavyweight floors

In order to measure the improvement of impact sound insulation ΔL due to a floor covering in accordance with ISO 10140 standard, a specialised measurement facility is required. As a consequence, such measurements become fairly expensive and available only to those who have access to a specialised laboratory. Therefore, the authors propose an engineering method to measure the ΔL value in the case of soft coverings placed on heavyweight floors. This method enables the replacement of extensive test facilities with one room with a heavyweight floor and a mobile insulation case inside. The inside of the case acts as a source room; the tapping machine and the test sample are placed inside the case, which separates the airborne sounds from the structure borne sounds. The measurement procedure described in ISO 10140 standard is adopted – ΔL is determined by the difference between the sound level outside the case with and without the test sample. In this article, the proposed engineering method is thoroughly delineated and verified with theoretical and energy (SEA) analyses. Next, the results of experimental tests are presented – the reduction of impact sound on four different groups of samples measured in three different rooms. The obtained results are compared with the corresponding ΔL values measured according to ISO 10140 standard. This comparison shows a very strong convergence between the curves of impact sound reduction obtained by both methods. Based on all the above findings, it is stated that the presented engineering method enables accurate measurements of impact sound reduction of heavyweight floors due to soft coverings within the range of uncertainty and application. Due to the reduced measurement facilities in comparison with the ISO standard, the engineering method can be a useful tool in the process of designing and improving products such as soft floor coverings.

<b>Suspended Floor Structure for Reducing Structure-borne Sound of Interior Noise</b>

<b>Suspended Floor Structure for Reducing Structure-borne Sound of Interior Noise</b>

Predicting In Situ Sound Levels Generated by Structure-Borne Sound Sources in Buildings

Predicting In Situ Sound Levels Generated by Structure-Borne Sound Sources in Buildings

Optimal Frequency Bands for Modeling the Coupling of Structure-Borne to Underwater Sound of a Surface Vessel

In this paper, we present a method for investigating the coupling of structure-borne sound (SBS) and underwater sound (UWS) of ships based on a decomposition in optimal frequency bands. The coupling is modeled by a linear regression model for sequences of spectral power, integrated over frequency intervals and moving time windows. As part of this analysis, a novel approach to detecting frequency intervals that bear particular relevance for the relationship between SBS and UWS is introduced. Regression models are regularized by a maximum-significance constraint. Cross correlations between UWS regressands and SBS regressors seem to be promising as quantitative measures for describing the coupling between SBS and UWS time series. The method is evaluated with experimental data recorded simultaneously from fixed SBS sensors onboard the research vessel R/V PLANET and from a freely drifting buoy system during an open-sea experiment north of the Outer Hebrides, Scotland, in 2011.

Effect of Urethane Foam Cushioning on Structure-Borne Sound Transfer by a Slab with Panel Flooring

Abstract Urethane foam mattresses are commonly used as cushioning when placing panel flooring on the floor slab of a building. Urethane foam consists of elastic fibres with pores. Both elements can affect the performance of the insulation against impact sounds. However, these effects have not yet been detailed, and they may change if the material properties or constitution of the fibres and pores in the cushioning change. In this paper, we propose an analytical model for use in evaluating the performance of insulation against floor impact sound. This model was used to examine the contribution of the pores versus the elastic fibres to wave transmissions from the flooring surface to the slab. The results reveal that the constitution of the foam (either open or closed cells of pores) and the thickness and hardness of the cushion layer strongly affect the sound insulation performance of the floor.

「舶用機関の騒音，固体音及び水中音の測定」の特集号によせて

「舶用機関の騒音，固体音及び水中音の測定」の特集号によせて

舶用機器メーカの空気音・固体音測定に関する注意事項

舶用機器メーカの空気音・固体音測定に関する注意事項

舶用機関の空気音と固体音の測定方法ガイドライン

舶用機関の空気音と固体音の測定方法ガイドライン

Online-monitoring for Abrasive Waterjet Cutting of CFRP via Acoustic Emission: Evaluation of Machining Parameters and Work Piece Quality Due to Burst Analysis

This paper deals with an additional option of online-monitoring for abrasive waterjet cutting processes. In the presented studies the carbon fibre reinforced polymer M21/T800S was machined under variation of different machining parameters, which are the machining pressure, the amount of abrasive and the feed speed. In a series of experiments linear cuts were monitored by measuring structure-borne sounds caused by the machining process. For the evaluation of the acoustic emission signals a burst analysis was applied using the acoustic emission sensor iMPact XS of the company iNDtact. In the investigations the count of bursts and the energy of the bursts are correlated with the machining process or rather the cutting quality. The results show that the machining parameters affect the acoustic emission signals significantly in a characteristic way. In conclusion the emitted bursts allow an evaluation of the cutting quality during the machining process.

Predicting the Interaction Between Structure-Borne Sound Sources and Receiver Structures from Independently Measured Quantities: Case Study of a Washing Machine on a Wooden Joist Floor

Predicting the Interaction Between Structure-Borne Sound Sources and Receiver Structures from Independently Measured Quantities: Case Study of a Washing Machine on a Wooden Joist Floor

Single Equivalent Approximation for Multiple Contact Structure-Borne Sound Sources in Buildings

The work reported in the paper addresses structure-borne sound transmission between multiple contact sources and non homogeneous plate receiver structures. This study concentrates on a practical method of predicting the installed structure-borne sound power from mechanical installations in lightweight buildings. The structure-borne sound power is a function of source activity, source mobility and receiver mobility, and all three quantities must be known to some degree. It is rarely practical to consider all transmission paths individually and in detail, and therefore, reduced data sets and less computationally demanding procedures are proposed. The paper examines how source data can be used to assemble single equivalent values, using spatial averages and magnitudes. Single equivalent values of receiver mobility also are proposed for lightweight, point-connected ribbed plate constructions. In case studies, the single equivalent values are used for predicting the structure-borne power in the installed condition.

Interface Mobilities for Characterization of Structure-Borne Sound Sources with Multi-Point Coupling

The concept of source descriptor and coupling function is commonly recognized to form a rigorous basis for structure-borne sound source characterization. While this concept initially is valid for the single-point case only, it can be extended to sources with multi-point coupling by including the interface mobility approach. By considering a continuous interface that passes all contact points, the velocities, forces and mobilities are series expanded into interface orders by means of a spatial Fourier decomposition. The use of a continuous formulation for the multi-point case, however, can be problematic from a practical point of view. This paper discusses a reformulation of the interface mobility approach for a simplified calculation and clarified interpretation of the interface orders. With a discrete Fourier series as a basis for the interface mobility approach, the interface is reduced to a set of points and the interface orders are shown to describe the interplay of the data at the contact points. A discrete formulation furthermore yields simplified equations and a strict upper bound for the number of orders that have to be included, thus enhancing the practicability of interface mobilities for source characterization.

338 固体音低減による温乳器のファン騒音の低減

338 固体音低減による温乳器のファン騒音の低減

Environmental and architectural acoustics

Fundamentals of Sound Waves and Hearing. Sound Waves. Speed of Sound. Impetence. Noise and Vibration - Measurement and Rating. Measurement of Sound/Noise. Noise Rating. Measurement of Vibration. Room Acoustics. Sound Field in a Room. Normal Modes of Vibration in Rooms. Reverberation Time. Sound Absorption - Materials and Construction. Types of Sound Absorption Mechanisms. Measurement of Absorption Coefficient and Acoustic Impetence. Characteristics of Porous Sound Absorber. Airborne Sound Insulation. Propagation and Transmission of Airborne Sound. Measurement and Rating of Airborne Sound Insulation. Mass Law for Sound Insulation of a Single Wall. Isolation of Structure-borne Noise and Vibration. Propagation and Radiation of Structure-borne Sound. Reduction of Structure-borne Noise. Measurement and Rating of Impact Sound Insulation. Noise and Vibration Control in the Environment. Basic Strategy. Determination of Required Reduction. Plan for Dealing with Noise and Vibration Sources. Acoustic Design of Rooms. Design Target. Design of Room Shape. Planning the Reverberation. Electro-acoustic systems. Function and Aim of Electro-acoustic Systems. Reinforcement Systems and Architectural Design. Prevention of Howling. Agenda. Wave Equation. Analogues in Electrical, Mechanical and Acoustic Systems and Time Constant. Fourier Transformation and Correlation Functions.