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Noise and Vibration Analysis is a complete and practical guide that combines both signal processing and modal analysis theory with their practical application in noise and vibration analysis.It provides an invaluable, integrated guide for practicing engineers as well as a suitable introduction for students new to the topic of noise and vibration.

With electric powertrains quickly advancing in the heavy vehicle sector, there is an increasing interest in the industry to find a general practice for evaluating tonal sounds. The challenge to set requirements is complex. Tonal sounds span from extremely annoying to pleasant. Established methods for prediction of tonal magnitude typically estimate individual tonal components without considering interrelations between the tones. In this study, the loudness perception of continuous complex tones with increasing number of harmonics as well as non-harmonic tone components, is assessed using pink noise as reference. Frequencies studied cover 350–11 000 Hz. These frequencies typically occur in electrified trucks, hitting the most sensitive area of the human hearing. The results show a statistically significant positive linear relationship between perceived loudness and increasing number of harmonics, even with decreasing level of amplitude (−6 dB/oct). Significant differences are seen between harmonic and non-harmonic tonal signals, when the second partial is detuned. Increasing the number of tonal components increases the perceived loudness linearly. Non-harmonic complex tonal sounds are assessed less loud than the corresponding harmonic sounds. In case of complex tonal sounds, models of loudness estimation need to take the number of tone components and their frequency ratios into account.

The sound generated by electric propulsion systems differs compared to the prevalent sound generated by combustion engines. By exposing listeners to various sound situations, the manufacturer can start understanding which direction to take to achieve compelling battery electric vehicle trucks from a sound perspective. The main objective of this study is to understand what underlying aspects decide the experience and perception of heavy vehicle–related sounds in the context of electrified propulsion. Using a thematic analysis of data collected at a listening experiment conducted in 2020, factors affecting the perception of novel sounds generated by a first-generation electric truck are investigated. A hypothesis is that the experience of driving or being a passenger in electric trucks will affect the rating and response differently compared to listeners not yet experienced with this sound. The results show that the combination of individual preference and experience, hearing function, acoustic content, time variation, signal stability, load-dependent feedback, and situation-equivalent sounds affect the outcome. The assessment and rating of quality and acceptance did not differ between battery electric truck experienced listeners and first-time listeners in general. The only driving condition clearly breaking this pattern was the auxiliary brake condition, which, besides being significantly higher rated by novel listeners, also stood out as the highest-rated and most positively commented driving operation overall. In conclusion, several combined factors affect the assessment of electric truck sounds. Three identified aspects are removing disturbing sounds, making the sound environment smooth and silent, and providing clear functional feedback. Memory of the contextual experience is a key factor when assessing sounds from driving operations. The expected difference between listeners with and without experience with electric truck sounds will be minor unless there is exceptionally high sound quality.

Ultrasound has many uses, such as in medical imaging, monitoring of crystallization, characterization of emulsions and suspensions, and disruption of cell membranes in the food industry. It can also affect microbial cells by promoting or slowing their growth and increasing the production of some metabolites. However, the exact mechanism explaining the effect of ultrasound has not been identified yet. Most equipment employed to study the effect of ultrasound on microorganisms has been designed for other applications and then only slightly modified. This results in limited control over ultrasound frequency and input power, or pressure distribution in the reactor. The present study aimed to obtain a well-defined reactor by simulating the pressure distribution of a sonobioreactor. Specifically, we optimized a sonotrode to match the bottle frequency and compared it to measured results to verify the accuracy of the simulation. The measured pressure distribution spectrum presented the same overall trend as the simulated spectrum. However, the peaks were much less intense, likely due to non-linear events such as the collapse of cavitation bubbles. To test the application of the sonobioreactor in biological systems, two biotechnologically interesting microorganisms were assessed: an electroactive bacterium, Geobacter sulfurreducens, and a lignocellulose-degrading fungus, Fusarium oxysporum. Sonication resulted in increased malate production by G. sulfurreducens, but no major effect on growth. In comparison, morphology and growth of F. oxysporum were more sensitive to ultrasound intensity. Despite considerable morphological changes at 4 W input power, the growth rate was not adversely affected; however, at 12 W, growth was nearly halted. The above findings indicate that the novel sonobioreactor provides an effective tool for studying the impact of ultrasound on microorganisms.

High-rise wooden buildings are increasing in popularity, and they typically include cross-laminated timber in the structure. Taller buildings result in higher loads on the junctions lower down in the building, which are suggested in the literature to negatively affect the sound insulation. This study involved measurement of the vibration reduction index in four different CLT buildings, varying in height and junction details. A total of 12 junctions were measured at both high and low levels in the buildings. Among these, 10 junctions had resilient interlayers with different stiffnesses dependent on the designed quasi-permanent load, while 2 junctions lacked resilient interlayers. The results indicated that the vibration reduction index decreases lower down in the building mainly for the Wall–Wall path. The findings were consistent for all measured junctions above 400 Hz for the Wall–Wall path and for the majority of the measurements of the remaining frequency range, 400 Hz and below. The observed difference in the vibration reduction index could significantly impact the final result if a high-rise building has several flanking paths that affect the sound insulation between two apartments, and this needs to be considered during the design phase. Similar effects were shown for buildings both with and without resilient interlayers in the junctions.

A new model for turbulent fibre suspension flow is proposed by introducing a model for the fibre orientation distribution function (ODF). The coupling between suspended fibres and the fluid momentum is then introduced through the second and fourth order fibre orientation tensors, respectively. From the modelled ODF, a method to construct explicit expressions for the components of the orientation tensors as functions of the flow field is derived. The implementation of the method provides a fibre model that includes the anisotropic detail of the stresses introduced due to presence of the fibres, while being significantly cheaper than solving the transport of the ODF and computing the orientation tensors from numerical integration in each iteration. The model was validated and trimmed using experimental data from flow over a backwards facing step. The model was then further validated with experimental data from a turbulent fibre suspension channel flow. Simulations were also carried out using a Bingham viscoplastic fluid model for comparison. The ODF model and the Bingham model performed reasonably well for the turbulent flow areas, and the latter model showed to be slightly better given the parameter settings tested in the present study. The ODF model may have good potential, but more rigorous study is needed to fully evaluate the model.

Many of the information systems in cars require visual attention, and a way to reduce both visual and cognitive workload could be to use sound. An experiment was designed in order to determine how driving and secondary task performance is affected by the use of information sound signals and their spatial positions. The experiment was performed in a driving simulator utilizing Lane Change Task as a driving scenario in combination with the Surrogate Reference Task as a secondary task. Two different signal sounds with different spatial positions informed the driver when a lane change should be made and when a new secondary task was presented. Driving performance was significantly improved when both signal sounds were presented in front of the driver. No significant effects on secondary task performance were found. It is recommended that signal sounds are placed in front of the driver, when possible, if the goal is to draw attention forward.

The number of advanced driver assistance systems is constantly increasing. Many of the systems require visual attention, and a way to reduce risks associated with inattention could be to use multisensory signals. A driver's main attention is in front of the car, but inattention to surrounding areas beside and behind the car can be a risk. Therefore, there is a need for driver assistance systems capable of directing attention to the sides. In a simulator study, combined visual, auditory and vibrotactile signals for directional attention capture were designed for use in driver assistance systems, such as blind spot information, parking assistance, collision warnings, navigation, lane departure warning etc. An experiment was conducted in order to measure the effects of the use of different sensory modalities on directional attention (left/right) in driver assistance systems. Attention was assessed in a driving simulator using Lane Change Task together with a secondary task, designed to measure choice response times and error rates to directional (left/right) information for multisensory signals. Different combinations of visual, auditory and vibrotactile signals were tested and compared. Visual signals alone (when captured by the driver) or in combination with other modalities provided shortest response times (570 ms on average). Auditory and vibrotactile signals captured attention equally well in terms of response time (650 ms and 740 ms on average). No significant differences in localization error rates were observed.

Comprehensively covers the basic principles and practice of Operational Modal Analysis (OMA). * Covers all important aspects that are needed to understand why OMA is a practical tool for modal testing * Covers advanced topics, including closely spaced modes, mode shape scaling, mode shape expansion and estimation of stress and strain in operational responses * Discusses practical applications of Operational Modal Analysis * Includes examples supported by MATLAB® applications * Accompanied by a website hosting a MATLAB® toolbox for Operational Modal Analysis

This article looks at surround sound in contemporary cinema, with the aim of discussing practices of sound design and, more particularly, pinpointing a ‘best practice’ of surround sound today – focusing here on the practices in the US. The empirical starting point for the analysis is a study of ten Oscar-nominated movies, analysing their soundtracks and especially comparing their stereo and surround versions. The method can be described as a ‘directional’ listening mode, analysing how the different channels and speakers are used when presenting sonic elements like voices, music, atmospheres and sound effects.