Sound Intensity Method Research Articles

Road-pavement classification by artificial neural network model based on tire-pavement noise and road-surface image

This study focuses on an artificial neural network (ANN) model for classifying pavement types using acoustic and image data. While conventional studies often use road-surface images for pavement classification, they face challenges with image quality degradation owing to external factors, such as sunlight angle, shadows, and lighting. Therefore, in this study, tire-pavement noise, which has different noise characteristics depending on the material and surface treatment, is used independently and in conjunction with image data for ANN training. To construct the training dataset, tire-pavement noise, and road-surface images are collected from 11 highway sampling sites in South Korea. Two simultaneous measurements are used: the tire-pavement noise is collected using the On-board sound intensity (OBSI) method, and the camera captures the road-surface images. 1/3 octave SIL, spectrum, MFCC, GLCM, and HOG are extracted from the raw data, and the ANN models are trained by these features. Using the spectrum as an input feature for the ANN yields a classification accuracy of 95.18%. However, the total number of parameters in the ANN is double that of the other models. To reduce the ANN size, 1/3 octave band SIL is used for training, and the model size is halved. However, the accuracy decreases by 13.47 percentage points. To overcome this significant decrease, the 1/3 octave bands SIL and image features were used to train ANN, simultaneously. This approach increases the accuracy by 93.85%. By training the ANN using MFCC, which is commonly used as an acoustic feature in other machine learning studies, the highest classification accuracy of 96.84% is achieved. Additionally, MFCC models are affected by the number of coefficients and the signal length. To include the dominant frequency of tire-pavement noise, more than 13 coefficients are used, a number generally known to be suitable for speech recognition. Increasing the number of coefficients from 13 to 40 improves accuracy by 1.17 percentage points. The interval for slicing raw WAV files is reduced to increase the training data and classify the pavement using shorter signals without statistically significant accuracy loss. Although accuracy does not decrease until the signal lengths reach 0.5 seconds, it rapidly decreases when the signal lengths become shorter than 0.4 seconds.

An investigation into vibration transmission patterns within metro turnout areas utilizing the structural sound intensity method

Urban rail transit turnout areas are notorious for inducing elevated environmental vibrations due to the complex interactions between wheels, rails, and supporting infrastructure. This paper establishes a comprehensive vehicle-track-tunnel-soil coupled dynamic model of a train traversing a turnout region. The intricate vibration transmission mechanisms within the turnout are explored through numerical simulation and visualization of vibration energy flow pathways. The structural sound intensity method facilitates the directional characterization of both transverse and longitudinal elastic waves emanating from the wheel-rail contact zone. Results reveal distinct propagation patterns between the switch panel and crossing panel, with more pronounced low-frequency energy backflow occurring in the switch panel. The transverse wave is found to dominate the elevated lateral vibrations observed along the tunnel walls. Frequency domain analysis maps the variation in energy flow directionality across one-third octave bands. The findings align closely with field measurement outcomes, validating the capacity of the approach to identify vibration "hot spots." Overall, this research enhances the theoretical comprehension of the complex interplay between diverse factors influencing turnout vibration transmission dynamics. The visualization technique proves instrumental in elucidating the critical mechanisms underlying the exacerbated environmental impact within these structurally intricate domains. Practical insights are distilled regarding turnout design strategies, vibration monitoring, and control methodologies to facilitate the mitigation of detrimental vibration effects.

Investigation of Medium-Term Performance of Porous Asphalt and Its Impacts on Tire/Pavement Noise

To assess the medium-term performance of porous asphalt pavement during service and its influence on tire/pavement noise level, a seven-year continuous observation and data analysis study was conducted. Key performance indicators were measured and calculated by using automated pavement technology testing equipment. The noise levels were tested by using the on-board sound intensity (OBSI) method on three types of porous asphalt pavements (PUC-10, PAC-13, and PUC-10 + PAC-13) and one dense thin layer course (DTC) for comparison. The findings indicated that the Damage Rate (DR) and Surface Friction Coefficient (SFC) of porous asphalt pavements diminished greatly over time, while the International Roughness Index (IRI) and Rut Depth (RD) remained relatively stable. The two-layer porous asphalt pavement showed the largest noise reduction over the medium-term. Compared to DTC, the OBSI noise levels of these structures were lower by 2.09 dB, 1.53 dB, and 2.88 dB, respectively. The OBSI was found to be closely correlated with the SFC, IRI, test speed, lane, and pavement type. The RD had a notable effect on the OBSI in PUC-10 pavements. In PUC-10 + PAC-13 pavements, a significant linear relationship was observed between the OBSI and SFC. This is mainly because of the polishing of the coarse aggregates, which leads to micro-texture reduction, high frequency noise increase, and SFC decrease. This study makes a valuable contribution to understanding the laws of porous asphalt pavement performance changes and the relationship between tire/pavement noise and pavement characteristics.

FMBEM simulation of the laboratory measurement of sound transmission loss in rectangular test rooms

In order to predict sound transmission loss of building elements, the fast multipole boundary element method is applied to simulate the laboratory measurement method in rectangular test rooms specified by ISO 10140-2 (JIS A 1416) for all the frequency bands from 100 to 4 kHz. Firstly, fine and simplified models are validated in comparison with theoretical and measured results for reference samples of membrane materials. Secondly, in addition to the sound pressure method, the sound intensity method is numerically simulated. As a result, it was shown that both models are applicable at mid and high frequency bands, but a simplified model overestimates the transmission loss more than a fine model at low frequency bands. Regarding the sound intensity method, the simulated values are lower than those with the sound pressure method, however approaching the theoretical values.

Comparison of microphone array techniques and standardized methods for sound power estimation

The sound power level can be estimated using several well-established techniques available in the market. However, the variety of methods can be overwhelming when choosing among them due to environmental restrictions, standard requirements, and the necessary expertise to acquire valid data. In this study, we aim to compare the results obtained with different techniques, either standardized, as described in ISO 3744 in hemi anechoic rooms and ISO 9614-1, engineering method, using sound intensity, and non-standardized microphone array methods, as optimized acoustic beamforming and acoustic holography algorithms. The sound power levels of an omnidirectional sound source with pink noise as input and a printer were measured in a hemi-anechoic chamber using all the techniques. In addition, the measurement with the omnidirectional sound source were carried in a meeting room to check the effect of room and background noise. Considering the results of the sound intensity method as the baseline, all the overall sound power level results varied within the uncertainty stipulated by ISO 9614-1 for both sources. The results in one-third octave bands were within the uncertainty for all bands except one case for both sources in the case of refined beamforming.

Vibration Energy Coupling Behavior of Rolling Mills under Double Disturbance Conditions

The operation of the world’s first multimode continuous casting and rolling F3 (3rd finishing mill stand) finishing mill was hampered by frequent vibrations. Mill vibrations were found to be caused by the transmission and coupling of vibration energy flow. In this study, an overall finite element model of the F3 stand is established based on the structural sound intensity method and harmonic response analysis method, and then, the intrinsic energy flow modes and energy flow harmonic response of the F3 stand are obtained. Further, the effects of the steady-state rolling force variation, preload torque variation, rolling force fluctuation, torque fluctuation, and its phase angle difference on the vibration energy flow of the mill are analyzed. Finally, the effects of the mill damping ratio, strip width, and strip modulus on the vibration energy flow under double dynamic load are discussed to reveal the inherent characteristics of the mill vibration energy flow. The results show that the vibration energy flow of the mill increases with the increase of strip modulus, rolling force, and moment fluctuation; the phase angle difference of rolling moment shows a “V” trend change on the vibration energy flow; the change of strip width has a greater effect on the vibration energy flow of the vertical system; and for the damping ratio of 0.01–0.1, the reduction of the vibration energy flow at all excitation frequencies is obvious.

Experimental investigation of possible improvements of ISO 9614

Sound power level is the key quantity to describe the noise emission of products and is needed to reduce noise at work, at home, and in the environment, e.g. for promoting and selecting low noise products (Sell and Buy Quiet). Sound power determination based on sound intensity measurements has advantages in non-ideal acoustic environments, e.g. indoors, but outside of acoustic test rooms, and is standardized in the ISO 9614 series. The current version of all three parts of ISO 9614 is their first edition. The advances of technology and knowledge indicate that the whole series should be revised. The improvement of the sound intensity method was investigated regarding a number of aspects. The use of a single spacer up to frequencies, which are outside of the currently usable frequency range, was studied. The effect of electrical noise was investigated to extend the applicability of the method to low noise sources. The discretization of the enveloping surface is discussed in relation to the accuracy grade of the measurements. The possibility to measure with more than one probes is also presented. The results indicate that there is the possibility for a substantial improvement of the ISO 9614 series.

Study the Effect of Parameters on Tire-Pavement Interaction Noise (TPIN)

The present study was prepared to determine the effect of different parameters on tire-pavement Interaction noise (TPIN). TPIN was calculated utilizing the Onboard Sound Intensity Method (OBSI) using apparatus Lutron 801 sound level meter single probe 1 kHz of one microphone is placed at the right back test tire with a specific distance. A total of 30 sections were selected for the main roads in Baghdad city, with 134 meters for each test section in length. TPIN data was calculated for various parameters such as different pavement types, various test vehicles, different speeds (40, 56, and 72) km/h, various types of tires, different pavement aging, and different mean texture depth (MTD) values Which is measured by a sand patch test. The sound intensity dBA increases when MTD value and vehicle speed increase in both types of pavements. On the other hand, the sound intensity dBA increases when age increases for asphalt pavement type while it decreases in asphalt concrete pavement type. In addition, the sound intensity dBA in the asphalt pavement type is lower than in the asphalt concrete pavement when compared to the condition of the new pavement. The opposite is in the case of old pavement surfaces. As well as, the sound intensity dBA in Bus is greater than in the passenger car, and the silver stone tire is lower than the Dunlop tire in the passenger car. Finally, it is concluded that TPIN may be reduced or increased due to the effect of different parameters.

Underwater multi-target passive detection based on transient signals using adaptive empirical mode decomposition

Underwater acoustic passive detection is the basis of target detection and recognition in underwater wireless sensor networks. However, with the development of noise reduction technology, the difficulty of passive detection on steady noise is increasing. Transient signals exposed by underwater targets under some circumstances are hard to be eliminated. To detect multiple quiet targets, different time scales of transient signals are studied and a multilayer adaptive separation method based on empirical mode decomposition is proposed. At first, the characteristics of different kinds of transient signals are analyzed. A mixed-signal model is established for simulation. Then, the empirical mode decomposition method is used to extract signal components from signal pieces, dividing the signal into a high-frequency part and a low-frequency part. The low-frequency part is resampled, and the complementary ensemble empirical mode decomposition with adaptive noise algorithm is used to solve the mode hybrid problem. Principle components are picked out, and start and end times of signal components are detected. Finally, the direction of arrival estimation of each signal component is realized in the average sound intensity method. In the process, the compromise between computation complexity and error is proposed to achieve online work. Experiment results show that different kinds of signals can be divided and directions of multiple targets can be well estimated.

Experimental study and analytical modeling of sound transmission through honeycomb sandwich panels using SEA method

This paper investigates the sound transmission through foam-filled honeycomb sandwich panels, experimentally and analytically. An analytical model based on statistical energy analysis (SEA) is developed in detail for a honeycomb sandwich panel. By using the SEA method, the sound transmission loss (STL) of honeycomb sandwich panels is described theoretically and a closed-form expression for the STL is presented. The resulting expression yields accurate predictions of transmission loss. The validity of the theoretical result is verified by implementation a comparison with experimental measurement. For this purpose, an experimental set-up was constructed for measuring the sound transmission loss. The set-up consisted of two reverberation chambers, a foam-filled honeycomb sandwich panel and a Brüel & Kjær intensity probe. The sound intensity method with the so-called direct approach was used to measure the transmission loss. Comparisons of the experimental and analytical results show good agreement in the medium and high frequency regions and particularly at the critical frequency of the panel. The critical frequency is estimated by the proposed SEA model with less than 1% error. The reported experimental results can also be used as reference data for further analytical and numerical studies. Based on the SEA theory developed, the effect of design parameters such as the thickness of the face and core layers, the internal loss factor of the sandwich panel and the shear modulus of the core layer on the sound transmission was studied.

Uncertainty of sound power measurements of a reference sound source using the AHRI Standard 230 sound intensity method

The uncertainty of determining the sound power of HVAC equipment using the AHRI Standard 230 sound intensity measurement method is presented. Measurements of six different reference sound sources (RSS) at four different laboratories, by nineteen different individuals with four different instrumentation systems are presented. From 2004 through 2020, these measurements were performed as part of a training program at Johnson Controls HVAC test laboratories to qualify technicians and engineers on the use of sound intensity instrumentation. The results illustrate the reproducibility of sound intensity measurements using the scanning method of AHRI Standard 230.

Acoustic Performance Evaluation of Dense-Graded Asphalt Pavements in Qatar

There is pressing and growing demand from the public to design and construct roads with a low noise level. This paper investigated the acoustic performance of asphalt pavements in the State of Qatar to assist transport authorities in designing and constructing quieter pavements. In this study, a field-testing setup was assembled to measure the tire-pavement noise of dense-graded asphalt (DGA) pavements at the source using the on-board sound intensity (OBSI) method. The repeatability and reproducibility of test results demonstrated that the assembled OBSI test setup could measure the sound intensity with excellent repeatability and reproducibility. The measured noise level of existing pavements varied from 101.8 dBA to 106.2 dBA depending on the age of pavement sections. Measured noise levels of pavements in Qatar were higher than typical DGA pavements in Europe and the US. Test results also demonstrated that the acoustic performance of pavements in Qatar deteriorates faster compared to those in the US and Europe. The findings of this study demonstrate that there is a need to consider alternative asphalt mixture designs in Qatar and the Arabian Gulf. The results also showed a good correlation between the mean texture depth of studied pavement sections and noise level, especially at the low-frequency range.

Low-Noise pavement technologies and evaluation techniques: a literature review

ABSTRACT Traffic noise is the perpetual form of environmental pollution adversely affecting human health in urban environments. This literature review, intended for pavement researchers and professionals, looks at the continuously evolving low-noise asphalt pavement technologies and the techniques which can be used to evaluate them. Test methods for determining the acoustical properties of asphalt pavements are reviewed, in both the laboratory and field environments. The Close-Proximity (CPX) method is the most commonly used field test for pavement acoustics, followed by the Statistical Pass-By (SPB) and On-Board Sound Intensity (OBSI) methods. SPB seems is the most comprehensive methods, while the CPX is more practical. Methods for measuring the acoustical properties in the laboratory include the impedance tube for sound absorption and laboratory pavement noise simulators; with only the larger drum methods being able to produce conditions similar to in-situ. Methods for noise-relevant non-acoustical characteristics like surface texture, porosity and airflow resistivity were also reviewed. Optimizing surface texture at the macro-scale was found to be important in reducing tire/road noise. For pavement types, porous asphalt concrete (PAC) and its variants result in low-noise properties the most reliably, while having some drawbacks in durability and maintenance. Finally, various acoustical performance prediction models were discussed.

AASHTO specifications for noise evaluations of pavement surfaces

Three specifications for the noise evaluation of pavement surfaces have been developed for the American Association of State Highway Transportation Officials (AASHTO). These include (1) the On-Board Sound Intensity (OBSI) method (AASHTO T-360-16) of directly measuring noise generated at the tire-pavement interface in isolation of other noise sources, (2) the Statistical Isolated Pass-By (SIP) method (AASHTO TP 98-13) of measuring noise from isolated vehicles in existing traffic, and (3) the Continuous-Flow Traffic Time Integrate (CTIM) method (AASHTO TP 99-18) of capturing the sound from existing traffic for all vehicles on all roadway lanes. This presentation will describe and compare the procedures of the three AASHTO measurement methods used for the noise evaluation of pavements.

The difference between several methods of sound power level for determining the sound energy emitted by a sound source

It is needed noise control by limiting the sound energy emitted by the source. The total sound energy emitted by a sound source in all directions per unit time is called sound power. There are several methods for measuring the sound power level emitted by a sound source. This study is comparing the sound power levels of a reference source Brüel&Kjær Type 4204 using sound pressure done in anechoic rooms and hemi-anechoic rooms method (ISO 3745), using reverberation test rooms method (ISO 3741), and using the sound intensity method (ISO 9614-3). This study result that there is a small difference between those methods.

In-door laboratory high-speed testing of tire-pavement noise

ABSTRACT The ability to measure traffic-speed tire-pavement noise in the laboratory is useful for predicting the tire-pavement noise performance of a design mix without conducting expensive and time-consuming field trials. This research developed an in-door high-speed test facility HTP2 for tire-pavement noise measurements. Housed in a semi-anechoic room, HTP2 has a circular test track of vertical wall, and a horizontal rotating arm system mounted with full-scale test tires. The test track can accommodate 12 specimens in each test run. The highest test speed achievable is currently 70 km/h, eventually 100 km/h when fully developed. The On-Board Sound Intensity Method was adopted for tire-pavement noise measurement. Tests were conducted to assess the reliability and repeatability of the test facility. Additional tests involving eight different pavement surface types were performed to illustrate that HTP2 was able to (i) measure sound intensity-frequency characteristics of tire-pavement noise matching those of actual vehicles and pavements, (ii) differentiate sound intensity of tire-pavement noise generated by different pavement types, (iii) identify increase in tire-pavement noise caused by texturing of concrete pavement, (iv) detect differences between tire-pavement noise generated by longitudinally and transversely tined concrete pavements, and (v) measure effects of surface macrotexture on tire-pavement noise.

Experimental modal analysis and vibro-acoustic testing at leonardo laboratories

This work deals with Experimental Modal Analysis and vibro-acoustic testing performed on several composite panels tested at Leonardo Laboratories, Pomigliano site. The main objective of this paper is to investigate the dynamical behaviour of the structure under test and to evaluate its acoustic properties. Several tests have been performed at the Trasmission Loss Facility of Leonardo.In a modal test, both the applied forces and vibration responses of the excited structure are measured in one or more locations. Exploiting this data, a Modal Model, that essentially contains the same information as the original vibration data, is derived by means of frequency-domain system identification techniques. A home-built Matlab algorithm, named “uMan”, is developed to perform a full Experimental Modal Analysis. Its performances, in terms of capability to build a useful stabilization chart and to curve-fit measured FRFs, are shown. Moreover, a comparison with respect to the state-of-art “Polymax” algorithm in LMS Test.Lab is provided. Finally, the numerical-experimental correlation is performed to verify consistency.The proposed algorithm identifies first mathematical polynomial models, rather than estimating the modal parameters directly from the measurements. Subsequently, these mathematical models are related to the modal parameters. Finally, the obtained Modal Model is compared to the analytical dataset.An acoustic test has been performed to experimentally investigate sound transmission. Two experimental methods have been adopted to evaluate the transmission loss. First, the method that includes measurements of the sound pressure levels using microphones is exploited. Then, the sound intensity method, in which the transmitted sound intensity is measured with a sound intensity probe, is used. By comparing both experimental techniques, the first showed better performance with respect to the other method at low frequencies, while the sound intensity method is more applicable in the medium and high frequency regions in order to predict the noise transmission characteristics.

Prediction models for distress noise generated due to tire-pavement surface interaction

The major objective of this research is to assess the distress noise generated due to tire-pavement surface interaction for different modes and to evolve a noise prediction model for any manner taking into consideration the different factors impacting the distress noise generation. Seven flexible and four rigid pavement roads were chosen for the calculation of the noise in Baghdad city. Tire-pavement interaction noise was calculated using Onboard Sound Intensity (OBSI) Method by restricting the noise generated from the vehicle exhaust and the engine systems. Prediction models were developed for assessing tire pavement noise from vehicle speed, pavement age, wheel load, mean texture depth (MTD) and pavement distresses. Four statistical models were obtained from this research to assess the distress noise generated due to tire-pavement surface interaction using linear regression stepwise method. These models showed the effect of different types of distresses in addition to the factors that have been taken into consideration on tire pavement noise. Vehicle speed was the greatest considerable variable influencing the noise generated due to tire-pavement surface interaction. Some distresses and factors have been excluded from the models due to their poor relationship with tire-pavement noise. These models have been categorized based on the type of pavement surface (flexible or rigid) and the presence or absence of pavement distresses. The predicted statistical models were verified with calculation, by comparing the data estimated by the models and data form field tests. Therefore, it can be used as a method of detecting distresses rather than visual inspection.

Analysis of Skid Resistance and Noise Characteristics for Varieties of Concrete Pavement

To establish evaluation criteria for the pavement skid resistance and noise level in tunnels pavements, the zoning and control standards for skid resistance and concrete pavement noise were examined. Transverse friction coefficient (TFC) test equipment and the on‐board sound intensity (OBSI) method were used to evaluate the antisliding characteristics and noise levels of several tunnel pavements. The results indicated poor antisliding characteristics and noise levels in ordinary grooved cement concrete pavement, whereas new types of cement concrete pavements, such as exposed concrete pavements and polymer‐modified cement concrete pavements, had good antisliding characteristics and achieved low noise levels. Combined with the cluster analysis method, a zoning method for the antisliding and noise level in concrete pavement is proposed. The antisliding characteristics and noise levels of the pavement are divided into three zones. To ensure safety and comfort during driving, the antisliding value (SFC) of the tunnel pavement should be more than 50, and the noise level should not exceed 105 dB. Finally, the correlation between the antisliding and noise levels for pavement was analyzed. The results indicated that the antiskiding value of pavement has a strong correlation to the noise level.

Sound power estimation with an acoustic camera in comparison with sound power determination using sound pressure and sound intensity method

Sound Power Level (SWL) is a measure to be used to describe a sound source regardless its surrounding and environment. In general, there are two different standardized methods to determine the Sound Power Level of a sound source, which are by using sound pressure and sound intensity. Other than that, there is a possibility to estimate Sound Power Level using an acoustic beamforming array or more popularly known as acoustic camera. This estimation is considered more time-efficient compared to the two methods and can be done when there are other sound sources during the measurement. However, this measurement is not yet standard compliant and therefore cannot be used for standardized reporting or legislative purposes.The paper highlights the possibility to estimate Sound Power Level of a Reference Sound Source using an acoustic beamforming array, when another sound source is present at the time of measurement. Besides comparing to the Reference Sound Source’s calibration chart, the measurement is compared with two ISO-compliant measurements which are ISO 3746 (Survey grade, sound pressure method) and ISO 9614-2 (survey grade, sound intensity method).