Acoustic Evaluation Research Articles

Evaluation of Aircraft Auxiliary Power Unit Near-Field Acoustics for Condition Monitoring

This paper presents a comprehensive evaluation of the near-field acoustics of an aircraft auxiliary power unit (APU), based on experimental data acquired from an in-situ APU. The aim is to establish whether near-field acoustics can be implemented for online condition monitoring. The APU of Cranfield University’s demonstrator aircraft, a Boeing 737-400, has been instrumented to acquire acoustics (near-field and far-field) and vibration data in synchronization with aircraft state parameters under a wide range of operating conditions. The acquired data is first implemented to determine the efficacy of employing near-field / far-field microphones, and vibration sensors, to monitor the combustion noise and tonal frequency levels from the APU components. Subsequently, an evaluation of the broadband characteristics of the vibroacoustic data and its variations against APU states and performance parameters is conducted based on several categories of feature extraction techniques. The findings suggest that nearfield acoustics lacks the ability to capture the combustion noise process. In addition, the tonal frequencies are also lost due to the level of background noise, fluctuations in the APU speeds, and scattering effects. For the same reasons, the phase couplings occurring between the signals generated by the APU components cannot be detected using acoustic data. Nevertheless, the overall analysis substantiates that the near-field acoustic data can be used to predict the APU operating states and has the potential to be implemented for developing APU performance parameter estimation models to enable condition monitoring.

Reduzindo o GAP entre a ciência e a clínica: lições da academia e da prática profissional – parte A: julgamento perceptivo-auditivo da qualidade vocal, análise acústica do sinal vocal e autoavaliação em voz

ABSTRACT During the XXVIII Brazilian Congress of SBFa, 24 specialists met and, from a leading position on scientific research as a tool for connecting laboratory and clinic, five fronts of knowledge of the voice specialty were discussed as following: Perceptual-auditory judgment of vocal quality; 2. Acoustic analysis of the vocal signal; 3. Voice self-assessment; 4. Traditional techniques of therapy; 5. Modern techniques of electrostimulation and photobiomodulation (PBMT) in voice. Part “a” of this publication was associated with the consolidation of the analyses of the first three aspects. The trend in the perceptual-auditory judgment of vocal quality was related to the use of standard protocols. The acoustic evaluation of the vocal signal is accessible and can be done descriptively or by extraction of parameters, thus preferring multiparametric measures. Finally, the analysis of the individual himself closes this triad of voice documentation, which will be the basis for the conclusion of the evaluation, reference for monitoring progress, and evaluation of treatment results.

Reducing the GAP between science and clinic: lessons from academia and professional practice - part A: perceptual-auditory judgment of vocal quality, acoustic vocal signal analysis and voice self-assessment.

During the XXVIII Brazilian Congress of SBFa, 24 specialists met and, from a leading position on scientific research as a tool for connecting laboratory and clinic, five fronts of knowledge of the voice specialty were discussed as following: Perceptual-auditory judgment of vocal quality; 2. Acoustic analysis of the vocal signal; 3. Voice self-assessment; 4. Traditional techniques of therapy; 5. Modern techniques of electrostimulation and photobiomodulation (PBMT) in voice. Part "a" of this publication was associated with the consolidation of the analyses of the first three aspects. The trend in the perceptual-auditory judgment of vocal quality was related to the use of standard protocols. The acoustic evaluation of the vocal signal is accessible and can be done descriptively or by extraction of parameters, thus preferring multiparametric measures. Finally, the analysis of the individual himself closes this triad of voice documentation, which will be the basis for the conclusion of the evaluation, reference for monitoring progress, and evaluation of treatment results.

Preliminary Archaeoacoustic Study of Kanheri Caves in Mumbai (Maharashtra, India)

Here we report first ever study on acoustical evaluation of Kanheri Caves located in Sanjay Gandhi National Park, Mumbai (Maharashtra, India). These caves are dated to a period between 2nd century BCE to 7th century CE. In this study we used an ambisonic recorder to capture Impulse Response, which carries acoustic signature of the place. Out of total 109 caves 41 were surveyed in available time. Out of those reverberant environment was noted in 12 caves. Measurements were made only in 3 caves (Cave Nos. 1, 3, 11) which are important. In the beginning we carried out an FFT analysis. We then studied room acoustic parameters like Reverberation Time, Early Decay Time, Clarity, Definition, etc., based on the measurement of Impulse response. Cave No. 3 have high value of reverberation time, compared to other. Therefore it also have lower clarity compared to others. It is properties needs to be compared with similar structures (chaityas) in Maharashtra (at Ajanta, Ellora, Nashik, Junnar, etc.) and elsewhere in India. It is worthwhile to carry out further research in Cave No. 3 with more sophisticated instruments as well as 3D modeling. Since the experiment was performed with receiver at only one position, we also suggest to carry out experiment with receiver at multiple positions and then comparing them.

Hard-Type Piezoelectric Materials Based Double-Parabolic-Reflectors Ultrasonic Transducer (DPLUS) for High-Power Ultrasound

To achieve wide-frequency (20 kHz-2 MHz) high-power output (10 MPa) of Double Parabolic refLectors wave-guided Ultrasonic tranSducers (DPLUS), this paper investigated the DPLUS with hard-type PZTs. Under resonant excitation of the DPLUS waveguide, around 30 harmonic longitudinal modes from the thin waveguide (1 mm in diameter and 40 mm long) can be excited between 20 kHz to 2 MHz. From 20 kHz to 0.4 MHz, the maximum peak vibration velocity was 7.5 m/s; from 1 MHz to 2 MHz, the maximum peak vibration velocity of hard-type PZT DPLUS (7 m/s) was 3.5 times of soft-type piezoelectric materials DPLUS (2 m/s). Acoustic evaluation revealed large acoustic pressure at a wide frequency range: 0.46 MPa (at 31 kHz), 10 MPa (at 590 kHz), 7.7 MPa (at 1.154 MHz), and 7.2 MPa (at 1.322 MHz). Results proved wide-frequency and high-power operation of DPLUS, which are significant for realizing various applications.

Perceptual, Aerodynamic and Acoustic Evaluation of Vocal Characteristics in Subjects With Obesity

Obesity has tripled since 1975 and affects health across many domains. Increasing body mass index increases the risk to the obese subject of many non-communicable diseases. The study evaluated the perceptive, aerodynamic, and acoustic parameters that characterize the voice of the obese population. Eighty adult subjects (40 participants in each obese and control group) aged 18-50 years were enrolled. The perceptual voice analysis was performed using the Consensus Auditory Perceptual Evaluation of Voice. The aerodynamic and acoustic voice analyses were performed using the MIR Spiro lab instrument and Doctor's Speech software. A digital stopwatch was also used to measure maximum phonation time. Statistical analysis revealed a significant difference (P-value <0.05 and t value >2) between two groups on acoustic parameters, specifically Normalized noise energy and fundamental frequency tremor (F0 tremor). Normalized noise energy and fundamental frequency tremor were greater in the obese group. Moreover, maximum phonation time and expiratory reserve volume were significantly reduced in the obese group. Results of the present study showed poor voice quality and reduced expiratory reserve volume in obese individuals. This could be credited to the adverse effects of accrued adipose on the functioning of the laryngeal and respiratory systems. Increasing body mass index escalates the risk to the obese subjects of many non-communicable diseases.

Urban Soundscape Assessment by Visually Impaired People: First Methodological Approach in Granada (Spain)

Soundscape assessments by citizens are starting to emerge as a common practice, normally carried out in context by means of soundwalks along selected paths with volunteers. However, when such assessments are carried out, either in situ or in laboratory experiments, visually impaired citizens are not usually involved. To address this question, three soundwalks were carried out in 2020 in the city of Granada, in southern Spain, with the participation of visually impaired people. In this paper, we present the lessons learnt from this research with respect to the methodology issues that have to do with soundwalking and the surveying procedures when people with limited vison are participating, the assessment results, and a comparison with a soundscape evaluation carried out in 2019 without the collaboration of visually impaired people. The results of this preliminary campaign highlight that: (1) Adapting soundscape assessment protocols from standards for visually impaired people is a methodological challenge that requires research attention; (2) Some of the different patterns in the assessment of the soundscape pleasantness between visually impaired and nonvisually impaired participants emerged; (3) The perception of quietness may differ for visually impaired people when orientation and identification are factors that play a role in the acoustic environment evaluation.

Correction to: A preliminary acoustic evaluation of three sites in the lagoon of Bora Bora, French Polynesia

Correction to: A preliminary acoustic evaluation of three sites in the lagoon of Bora Bora, French Polynesia

A Multisensory Deficit in the Perception of Pleasantness in Parkinson's Disease.

There is growing interest in non-motor symptoms in Parkinson's disease (PD), due to the impact on quality of life. Anhedonia, the inability to experience joy and lust, has a prevalence of up to 46% in PD. The perception of pleasantness of an odor is reduced in anhedonia without PD. We previously showed a reduced hedonic olfactory perception in PD, i.e., patients evaluated odors as less pleasant or unpleasant compared to controls. This deficit correlated with anhedonia. We aimed to confirm these findings. Moreover, we hypothesized that the perception of pleasantness in PD is affected on a multisensory level and correlates with anhedonia. Therefore, we assessed olfactory, visual and acoustic evaluation of pleasantness in PD and healthy individuals. Participants had to rate the pleasantness of 22 odors, pictures, and sounds on a nine-point Likert scale. Depression, anhedonia, and apathy were assessed by means of questionnaires. Results of the pleasantness-rating were compared between groups and correlated to scores of the questionnaires. In particular pleasant and unpleasant stimuli across all three modalities are perceived less intense in PD, suggesting that a reduced range of perception of pleasantness is a multisensory phenomenon. However, only a reduction of visual hedonic perception correlated with anhedonia in PD. A correlation of reduced perception of pleasantness with apathy or depression was not present. We provide evidence for a multisensory deficit in the perception of pleasantness. Further studies should delineate the underlying neural circuity and the diagnostic value to detect neuropsychiatric symptoms in PD.

Accuracy of Acoustic Evaluation of Swallowing as a Diagnostic Method of Dysphagia in Individuals Affected by Stroke: Preliminary Analysis.

After a stroke, more than half of the patients have some kind of disability, and dysphagia is frequently found. Cervical auscultation by Doppler sonar is an innovative technique with gain of credibility in the clinical evaluation of swallowing. To verify the diagnostic accuracy of Doppler sonar along with the DeglutiSom® software as an auxiliary method in the evaluation of oropharyngeal dysphagia in patients after stroke. The research is a cross-sectional, uncontrolled, blind, quantitative study with systematic random sampling. Patients from inpatient and outpatient units of a reference hospital with a stroke care unit were concomitantly submitted to both Doppler sonar and Fiberoptic Endoscopic Evaluation of Swallowing (FEES®). Seventy-three audio files collected from 26 patients through Doppler sonar were analyzed using DeglutiSom® software and confronted with the FEES® report, regarding three food consistencies offered to them during the exam. The study showed that the Doppler sonar correctly identified, among all the analyzed files, those that actually presented tracheal aspiration as well as it effectively identified patients who did not aspirate. The Youden index of 0.91 corroborates this information, showing a promising accuracy in detecting tracheal aspiration in the studied sample. The study evaluates the diagnostic accuracy of Doppler sonar, showing that it can be used as a valuable tool in the diagnosis of tracheal aspiration in patients after stroke. It is important to emphasize that the identification of residue by this method requires further studies. Also, larger sample size and more than one blind evaluator should be considered in future researches to increase the reliability of the proposed method.

Helicopter Inside Cabin Acoustic Evaluation: A Case Study-IAR PUMA 330.

This paper presents an inside-cabin acoustic evaluation of the IAR PUMA 330 helicopter, manufactured by IAR S.A. Brasov. In this study, based on the acoustic assessment inside the helicopter, areas with high noise levels are identified. In this regard, several tests were carried out in accordance with the ISO 5129 standard. In the first stage of the assessment, a measurement campaign was performed to identify the acoustic leaks from the outside noise sources propagating inside the cabin (in the door area) and the acoustic attenuation of the helicopter structure. These tests were performed on the factory runway, with the helicopter in parked position (ground tests). During the ground tests, the helicopter engines were turned off. The tests consisted of placing two loudspeakers directed towards the helicopter door and generating pink noise. Inside the helicopter, the entire door frame opening was scanned with an intensity probe to identify acoustic leaks areas. The second assessment stage was to determine the areas of the cabin with the highest levels of noise. Within the measurement campaign, 16 microphones were placed inside the cabin, at the level of the passengers’ heads, arranged in seven zones. The tests were carried out with the helicopter engines started, staying at fixed point above the ground (hovering), and then a flight test, in which all the maneuvers necessary for the use of the helicopter were performed (in-flight tests). Based on the measurement results, it was possible to highlight the noise spectral components in each of the seven areas. The noise assessment revealed high noise levels inside the cabin, having as main noise sources the transmission gear and the door area, leading to the need for reducing the noise exposure for passengers and crew, thus the need to reduce noise levels inside the helicopter.

Utilization of psychoacoustic parameters for occupancy-based acoustic evaluation in eating establishments

Utilization of psychoacoustic parameters for occupancy-based acoustic evaluation in eating establishments

Aerodynamic design and acoustic effect study of key geometric parameters of a sirocco fan

A sirocco fan (forward-curved centrifugal fan), including impeller blades and volute, is designed, and the empirical value ranges of several significant design parameters are discussed and summarized fromthe perspective of both aerodynamics and practical structure. Unsteady-flow numerical simulation and radiated sound-field calculation by indirect boundary element method are combined to evaluate its aerodynamic and acoustic performances. Both the discrete noise source from the rotating impeller and broadband noise source from the volute are considered. Obvious flow separation occurs in the flow passage of impeller blades due to large angle of attack, and the tongue region is the major noise source area due to the small impeller-tongue gap. Therefore, parametric studies for blade installation angle and impeller-tongue gap are performed. Analyses of flow- and sound-field indicate that appropriate reduction of blade geometry incidence angle weakens the flow separation, thereby improving both the aerodynamic and acoustic performances, and reasonable increase of the impeller-tongue gap has a remarkable noise reduction effect for the major noise source area near the volute tongue. The optimized sirocco fan meets the requirement of the industrial project, i.e., the far-field A-weighted sound power level lower than 64.0 dB(A), and achieves larger volume flow rate and total pressure rise. The results also imply that fast steady-flow numerical simulation result is indicative of the acoustic performance to some extent if the acoustic evaluation is urgent. Furthermore, optimization of the key structural parameters in the stage of design is preferable in practical engineering, instead of taking follow-up noise reduction measures.

Study on acoustic environment of canteens in South China University of Technology

In order to understand the characteristics of the acoustic environment of University canteens, the canteens of South China University of Technology were selected as the research objects, and the acoustic parameters were measured on the spot and the questionnaire survey was conducted. The results show that the average sound pressure level of restaurants with smaller area is lower than that of restaurants with larger area, and the sound pressure level of dining space first increases rapidly, then increases slowly, and finally remains unchanged with the increase of the number of diners. In the aspect of restaurant acoustic environment satisfaction evaluation, the space with the smallest dining area has the highest acoustic environment satisfaction evaluation level, and the collision sound of tableware collection and table and chair moving has the highest correlation with the acoustic environment satisfaction evaluation. In terms of different types of noise sources, diners think that the most disturbing noise for conversation is the voice of the surrounding people, followed by the collision of tables and chairs and the collection of tableware, and the least disturbing noise is the noise of air conditioning and kitchen equipment.

Measurement survey using acoustic measurement network and sound environment evaluation system by experience sampling

The use of open-plan offices is increasing as they are effective in improving intellectual productivity by fostering a communication among workers. Previous research on the relationship between the indoor sound environment and intellectual productivity has mostly reported the impact of the sound environment on the tasks that individuals work on. However, there has been no research on the impact of sound environment on office spaces where multiple workers are actually working. In this study, we developed a system that can analyze the individual characteristics of workers in relation to the sound environment by simultaneously measuring their evaluation to the sound environment and the sound environment of the office. The system collected workers' evaluation of their impressions to the sound environment through a regular questionnaire using the experience sampling method. At the same time, it measured the sound environment of the office with multiple small measurement devices. The obtained sound environment evaluation data and the acoustic data of the office were stored in a single database. Finally, this system was run in a working environment to evaluate the sound environment on a trial basis.

Evaluation of the performance of machine learning algorithms applied to voice parameters in prioritizing candidate for office laryngoscopy: Automated triaging in focus

Background: We examined the performance of different Machine Learning Algorithms while also comparing two methods of voice assessment to look at the workability of automating triage of patient that will need prompt office laryngoscopy. Methods: We recruited consecutive adult subjects excluding those with a history of being regular singers or choristers in the past one year and those with the previous history of laryngeal trauma. We then carried out the perceptual voice assessments on the GRBAS Scale and also obtained the basic acoustic parameters of the voice samples. Laryngeal examinations with 70-degree Hopkins’ Rod were then carried out by another examiner for all the participants to identify gross laryngeal changes or lesions. We then evaluated each machine learning algorithm comparing the perceptual and acoustic parameters in determining how well each algorithm predicts the presence of those categorized with having lesion or not by the laryngeal examination. Results: One hundred and twenty respondents were analyzed out of which 89(74.2%) were females. The mean age was 46.5 ± 9.2 years. The perceptual evaluation generally outperformed the acoustic evaluation. Also, the Naïve Bayes Classifier (NBC) outperformed other algorithms with a F1 score of 0.55 followed by Artificial Neural Network (ANN) with the score of 0.53. However, the ANN outperformed the other with regards to the Area-under-the-curve (AUC). Conclusion: When these metrics are taken together, the ANN still remains the best algorithm for this dataset. We are however cognisance of the needed improvement to the various aspects of this work including a larger dataset more scientific sampling.

BIM-based energy and acoustic analysis through CVE tools

Building information modelling (BIM) is trying to overcome the issue of interoperability by promoting the collaboration between different professions, which enables Building Performance Assessments (BPA) to take place earlier in the design process. Nevertheless, the interoperability is rarely perfect and information is lost during translation from BIM authoring tool to simulation software or the interoperability is limited to the translation of the geometry. The discrepancies in data translations from BIM authoring tool to specific Calculation Virtual Environments (CVE) for energy and acoustic evaluation are considered. For the energy performance evaluation two software tools are tested in the present research paper, namely the Design Builder and IES VE , using IFC and gbXML as data exchange formats. Furthermore, a solution is proposed for overcoming the interoperability issue about acoustic evaluation by adapting programming language in Dynamo Graphical Interface for calculation of acoustic parameters, namely the Reverberation time and Schroeder’s frequency, which allow room quality evaluation to take place earlier in the design process as they are crucial for educational and other facility usage buildings.

Multi Parametric Method for the Objective Acoustic Evaluation of the Voice Produced by Laryngectomy Patients

A reliable perceptive analysis implying several sessions of listening turns out to be consuming in time and in human resources, and therefore not allowing a regular use in clinical practice. At the level of the Ear, Nose and Throat (ENT) services the rehabilitative speech therapist is in charge of estimating by listening to the quality of the voice, which entraines a non reliable perceptive evaluation compared with the one that will be proposed in this work. In this study, objective instrumental approaches based on physical measures has been proposed. These approaches allowing the analysis and estimation of the acoustic characteristics of the voice of the patients having a total laryngectomy. The results are compared with those obtained in a healthy vocal speaker. The outcomes indicate that objective evaluations can provide a homogeneous database for a better interpretation of articulators and vocal dysfunctions.

The effects of alendronate on the suppression of bone resorption and the promotion of cartilage formation in the human mosaicplasty donor site: A randomized, double-blind, placebo-controlled prospective study

BackgroundWe previously reported that early alendronate administration accelerated bone formation and improved the quality of repaired cartilage in the donor site in rabbits. To investigate whether alendronate administration has effects in humans similar to those observed in rabbits. MethodsThe study cohort included 35 patients over the age of 12-years old who underwent mosaicplasty without osteoporotic therapy from March 2011 to October 2012. The donor sites were medial or lateral in the patellofemoral joint. Placebo (P) or Bonalon containing 35 mg of alendronate (A) was administered orally every week for 8 weeks. The cohort comprised 15 male and 20 female, including 14 right and 21 left knees. The mean age at the time of surgery was 57.1 years. Bone formation was examined using computer tomography and lateral knee radiography, and cartilage formation was examined using magnetic resonance imaging (MRI), second-look assessment, and intraoperative acoustic evaluation. The clinical outcomes were assessed using the Japanese Orthopaedic Association knee score and visual analog scale (VAS). Bone and cartilage formation in the donor site and clinical outcomes were assessed at 3, 6, and 12 months after mosaicplasty. ResultsThe ratio of TRAP-5b in group A was significantly smaller than that in group P at 2 and 8 weeks after mosaicplasty. The extent of bone formation in the donor sites in group A was significantly greater than that in group P at 3 and 6 months after mosaicplasty. Cartilage formation did not differ significantly between the two groups as determined by MRI, macroscopic assessment, and intraoperative acoustic evaluation. Clinical outcomes did not differ significantly between the two groups, and no negative clinical outcomes were observed. ConclusionEarly alendronate administration accelerated bone formation but not cartilage formation in the mosaicplasty donor site in humans.

자폐스펙트럼장애 아동의 후두 높이 및 음성 특성*

The purpose of this study was to investigate laryngeal characteristics in children with autism spectrum disorders (ASD). A total of 50 children participated, including eight children aged 2 to 4 years old diagnosed with ASD and 42 normal controls at the same age. All children recorded X-ray images of the midsagittal plane of the cervical spine and larynx, and compared the laryngeal positions of ASD and control. In addition, samples of children with vowel prolongation were collected and analyzed for acoustic parameters. X-rays showed that the height of the hyoid bone in the normal group was the lowest at 3 years of age, and ascended at 4 years of age. Nevertheless, the distance from the external acoustic meatus to the hyoid bone was longest at age 4. 4-year-olds with explosive language development showed laryngeal height elevation and anteriorization. In contrast, the hyoid height of the ASD group of all ages was lower than that of the control group, and there was no difference in the hyoid position between the ages. As a result of acoustic evaluation, PFR, vFo, and vAm were significantly higher ASD than control. Low laryngeal height of ASD children may be associated with delayed language development. PFR, vFo, and vAm seem to be voice markers showing the difference between normal and ASD children.