Displaying publications 41 - 60 of 73 in total

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  1. Fulltext Rewinding the waves: tracking underwater signals to their source
    Kadri U, Crivelli D, Parsons W, Colbourne B, Ryan A
    Sci Rep, 2017 10 24;7(1):13949.
    PMID: 29066744 DOI: 10.1038/s41598-017-14177-3
    Analysis of data, recorded on March 8th 2014 at the Comprehensive Nuclear-Test-Ban Treaty Organisation's hydroacoustic stations off Cape Leeuwin Western Australia, and at Diego Garcia, reveal unique pressure signatures that could be associated with objects impacting at the sea surface, such as falling meteorites, or the missing Malaysian Aeroplane MH370. To examine the recorded signatures, we carried out experiments with spheres impacting at the surface of a water tank, where we observed almost identical pressure signature structures. While the pressure structure is unique to impacting objects, the evolution of the radiated acoustic waves carries information on the source. Employing acoustic-gravity wave theory we present an analytical inverse method to retrieve the impact time and location. The solution was validated using field observations of recent earthquakes, where we were able to calculate the eruption time and location to a satisfactory degree of accuracy. Moreover, numerical validations confirm an error below 0.02% for events at relatively large distances of over 1000 km. The method can be developed to calculate other essential properties such as impact duration and geometry. Besides impacting objects and earthquakes, the method could help in identifying the location of underwater explosions and landslides.
    Matched MeSH terms: Sound
  2. Fulltext Aquifer Potential Assessment in Termites Manifested Locales Using Geo-Electrical and Surface Hydraulic Measurement Parameters
    Ahmed Ii JB, Pradhan B, Mansor S, Yusoff ZM, Ekpo SA
    Sensors (Basel), 2019 May 07;19(9).
    PMID: 31067734 DOI: 10.3390/s19092107
    In some parts of tropical Africa, termite mound locations are traditionally used to site groundwater structures mainly in the form of hand-dug wells with high success rates. However, the scientific rationale behind the use of mounds as prospective sites for locating groundwater structures has not been thoroughly investigated. In this paper, locations and structural features of termite mounds were mapped with the aim of determining the aquifer potential beneath termite mounds and comparing the same with adjacent areas, 10 m away. Soil and species sampling, field surveys and laboratory analyses to obtain data on physical, hydraulic and geo-electrical parameters from termite mounds and adjacent control areas followed. The physical and hydraulic measurements demonstrated relatively higher infiltration rates and lower soil water content on mound soils compared with the surrounding areas. To assess the aquifer potential, vertical electrical soundings were conducted on 28 termite mounds sites and adjacent control areas. Three (3) important parameters were assessed to compute potential weights for each Vertical Electrical Sounding (VES) point: Depth to bedrock, aquifer layer resistivity and fresh/fractured bedrock resistivity. These weights were then compared between those of termite mound sites and those from control areas. The result revealed that about 43% of mound sites have greater aquifer potential compared to the surrounding areas, whereas 28.5% of mounds have equal and lower potentials compared with the surrounding areas. The study concludes that termite mounds locations are suitable spots for groundwater prospecting owing to the deeper regolith layer beneath them which suggests that termites either have the ability to locate places with a deeper weathering horizon or are themselves agents of biological weathering. Further studies to check how representative our study area is of other areas with similar termite activities are recommended.
    Matched MeSH terms: Sound
  3. Rigid/flexible polyurethane foam composite boards with addition of functional fillers: acoustics evaluations
    Huang C, Lou C, Chuang Y, Lin J, Liu C, Yu Z
    Sains Malaysiana, 2015;44:1757-1763.
    Following rapid technological and industrial development, factories have been equipped with a great deal of machines.
    The blend of industrial and residential areas in turn resulted in many environmental problems. In particular, machine
    operation causes noise pollution that easily causes physiological and psychological discomfort for the human body thus
    makes noise abatement a crucial and urgent issue. In this study, vermiculite functional fillers were added to polyurethane
    (PU) foam mixtures in order to form sound absorbent PU foams. The correlations between the contents of functional fillers
    and the sound absorption of flexible and rigid PU foams were then examined. The optimal PU foams were combined with
    PET/carbon fiber matrices in order to yield the electromagnetic shielding effectiveness. The sound absorption, noise
    reduction coefficient (NRC), electromagnetic shielding effectiveness and resilience rate of the composite boards were
    finally evaluated. The test results indicated that rigid PU foam composites can reach a sound absorption coefficient of
    0.8 while the flexible PU foam composites have higher mechanical properties.
    Matched MeSH terms: Sound
  4. Fulltext Development of Mandarin fricative-affricate nonsense word test: part 1. selection of best exemplars
    Chong Foong Yen, Lee Onn Wah, Norfazilah Abdol, Rafidah Mazlan
    Jurnal Sains Kesihatan Malaysia, 2018;16(101):179-185.
    MyJurnal
    A speech test that emphasizes on fricatives and affricates with high-frequency components is recommended for testing individuals with high-frequency hearing loss. Validation of the frequency-lowering feature in modern hearing aids are also important. There has been no recorded speech material in Malaysia that focuses on Mandarin fricatives and affricates. Therefore, the objective of this study was to develop a nonsense word test that contains Mandarin sibilant fricatives and affricates. A total of 180 vowel-consonant-vowel (vcv) nonsense syllables were recorded from a female and a male talker. These vcv syllables included six targeted Mandarin fricatives and affricates in three vowel contexts. Perceptual and acoustic analysis were conducted and selected vcv syllables were validated by 24 native Mandarin talkers with normal hearing through identification testing. Hundred and three syllables were rated as having a good or excellent sound quality and free from at least one of the idiosyncrasy elements. The average percentage of correct identification of vcv tokens for the female and male talkers were 85.38% and 82. 73%, respectively. Syllables that received the highest correct identification scores above the group mean were taken as the best exemplars. In total, 29 best exemplars were selected from 180 vcv syllables for the development of the Mandarin fricative-affricate nonsense word test. Future studies should include the development of performance-intensity function for individuals with normal hearing and a test manual so that the test can be used by non-native Mandarin clinicians.
    Matched MeSH terms: Sound
  5. The electronic song "Scary Monsters and Nice Sprites" reduces host attack and mating success in the dengue vector Aedes aegypti
    Dieng H, The CC, Satho T, Miake F, Wydiamala E, Kassim NFA, et al.
    Acta Trop, 2019 Jun;194:93-99.
    PMID: 30922800 DOI: 10.1016/j.actatropica.2019.03.027
    Sound and its reception are crucial for reproduction, survival, and population maintenance of many animals. In insects, low-frequency vibrations facilitate sexual interactions, whereas noise disrupts the perception of signals from conspecifics and hosts. Despite evidence that mosquitoes respond to sound frequencies beyond fundamental ranges, including songs, and that males and females need to struggle to harmonize their flight tones, the behavioral impacts of music as control targets remain unexplored. In this study, we examined the effects of electronic music (Scary Monsters and Nice Sprites by Skrillex) on foraging, host attack, and sexual activities of the dengue vector Aedes aegypti. Adults were presented with two sound environments (music-off or music-on). Discrepancies in visitation, blood feeding, and copulation patterns were compared between environments with and without music. Ae. aegypti females maintained in the music-off environment initiated host visits earlier than those in the music-on environment. They visited the host significantly less often in the music-on than the music-off condition. Females exposed to music attacked hosts much later than their non-exposed peers. The occurrence of blood feeding activity was lower when music was being played. Adults exposed to music copulated far less often than their counterparts kept in an environment where there was no music. In addition to providing insight into the auditory sensitivity of Ae. aegypti to sound, our results indicated the vulnerability of its key vectorial capacity traits to electronic music. The observation that such music can delay host attack, reduce blood feeding, and disrupt mating provides new avenues for the development of music-based personal protective and control measures against Aedes-borne diseases.
    Matched MeSH terms: Sound
  6. Mating calls of selected Sarawak toads (Amphibia: Anura: Bufonidae)
    Muhammad Fadzil Amram, Ramlah Zainudin, Hasnizam Abdul Wahid
    Sains Malaysiana, 2018;47:1-7.
    The sound produced by the anurans including toads can be a survival strategy for the selection of fittest males by their conspecific females and a form of effective prezygotic mechanism. Most of the published works on anuran sound production were on true frogs or ranids, yet little is known about sound characteristics of toads. Here we describe the properties of mating calls from six selected toad species from six study sites in Sarawak. Males' mating calls were recorded and analyzed using Sound Ruler Acoustic Analysis ver 0.9.6.0. Call characteristic were subsequently compared for toad species differentiation. The results showed that each species differ in call characteristics, with pulsating note, rate of note repetition and pitch being the most apparent characters. The highest number of pulse notes belongs to Duttaphrynus melanostictus while Ansonia spinulifer exhibited highest pitch and rate of note repetition. These species' differences in mating call characteristics provide an additional method for anuran species classification besides morphological and molecular DNA data. It is also a very useful guide during field survey as the sound is audible and identification can be made without the need of capturing the toads.
    Matched MeSH terms: Sound
  7. Fulltext Vocalisations of the bigeye Pempheris adspersa: characteristics, source level and active space
    Radford CA, Ghazali S, Jeffs AG, Montgomery JC
    J Exp Biol, 2015 Mar;218(Pt 6):940-8.
    PMID: 25617461 DOI: 10.1242/jeb.115295
    Fish sounds are an important biological component of the underwater soundscape. Understanding species-specific sounds and their associated behaviour is critical for determining how animals use the biological component of the soundscape. Using both field and laboratory experiments, we describe the sound production of a nocturnal planktivore, Pempheris adspersa (New Zealand bigeye), and provide calculations for the potential effective distance of the sound for intraspecific communication. Bigeye vocalisations recorded in the field were confirmed as such by tank recordings. They can be described as popping sounds, with individual pops of short duration (7.9±0.3 ms) and a peak frequency of 405±12 Hz. Sound production varied during a 24 h period, with peak vocalisation activity occurring during the night, when the fish are most active. The source level of the bigeye vocalisation was 115.8±0.2 dB re. 1 µPa at 1 m, which is relatively quiet compared with other soniferous fish. Effective calling range, or active space, depended on both season and lunar phase, with a maximum calling distance of 31.6 m and a minimum of 0.6 m. The bigeyes' nocturnal behaviour, characteristics of their vocalisation, source level and the spatial scale of its active space reported in the current study demonstrate the potential for fish vocalisations to function effectively as contact calls for maintaining school cohesion in darkness.
    Matched MeSH terms: Sound Spectrography
  8. Fulltext Surface Acoustic Wave (SAW) Sensors for Hip Implant: A Numerical and Computational Feasibility Investigation Using Finite Element Methods
    Hafizh M, Soliman MM, Qiblawey Y, Chowdhury MEH, Islam MT, Musharavati F, et al.
    Biosensors (Basel), 2023 Jan 02;13(1).
    PMID: 36671914 DOI: 10.3390/bios13010079
    In this paper, a surface acoustic wave (SAW) sensor for hip implant geometry was proposed for the application of total hip replacement. A two-port SAW device was numerically investigated for implementation with an operating frequency of 872 MHz that can be used in more common radio frequency interrogator units. A finite element analysis of the device was developed for a lithium niobate (LiNBO3) substrate with a Rayleigh velocity of 3488 m/s on COMSOL Multiphysics. The Multiphysics loading and frequency results highlighted a good uniformity with numerical results. Afterwards, a hip implant geometry was developed. The SAW sensor was mounted at two locations on the implant corresponding to two regions along the shaft of the femur bone. Three discrete conditions were studied for the feasibility of the implant with upper- and lower-body loading. The loading simulations highlighted that the stresses experienced do not exceed the yield strengths. The voltage output results indicated that the SAW sensor can be implanted in the hip implant for hip implant-loosening detection applications.
    Matched MeSH terms: Sound
  9. Fulltext I feel you: the design and evaluation of a domotic affect-sensitive spoken conversational agent
    Lutfi SL, Fernández-Martínez F, Lorenzo-Trueba J, Barra-Chicote R, Montero JM
    Sensors (Basel), 2013;13(8):10519-38.
    PMID: 23945740 DOI: 10.3390/s130810519
    We describe the work on infusion of emotion into a limited-task autonomous spoken conversational agent situated in the domestic environment, using a need-inspired task-independent emotion model (NEMO). In order to demonstrate the generation of affect through the use of the model, we describe the work of integrating it with a natural-language mixed-initiative HiFi-control spoken conversational agent (SCA). NEMO and the host system communicate externally, removing the need for the Dialog Manager to be modified, as is done in most existing dialog systems, in order to be adaptive. The first part of the paper concerns the integration between NEMO and the host agent. The second part summarizes the work on automatic affect prediction, namely, frustration and contentment, from dialog features, a non-conventional source, in the attempt of moving towards a more user-centric approach. The final part reports the evaluation results obtained from a user study, in which both versions of the agent (non-adaptive and emotionally-adaptive) were compared. The results provide substantial evidences with respect to the benefits of adding emotion in a spoken conversational agent, especially in mitigating users' frustrations and, ultimately, improving their satisfaction.
    Matched MeSH terms: Sound Spectrography/methods*
  10. Optimization of MFCC parameters using Particle Swarm Optimization for diagnosis of infant hypothyroidism using Multi- Layer Perceptron
    Zabidi A, Lee YK, Mansor W, Yassin IM, Sahak R
    Annu Int Conf IEEE Eng Med Biol Soc, 2010;2010:1417-20.
    PMID: 21096346 DOI: 10.1109/IEMBS.2010.5626712
    This paper presents a new application of the Particle Swarm Optimization (PSO) algorithm to optimize Mel Frequency Cepstrum Coefficients (MFCC) parameters, in order to extract an optimal feature set for diagnosis of hypothyroidism in infants using Multi-Layer Perceptrons (MLP) neural network. MFCC features is influenced by the number of filter banks (f(b)) and the number of coefficients (n(c)) used. These parameters are critical in representation of the features as they affect the resolution and dimensionality of the features. In this paper, the PSO algorithm was used to optimize the values of f(b) and n(c). The MFCC features based on the PSO optimization were extracted from healthy and unhealthy infant cry signals and used to train MLP in the classification of hypothyroid infant cries. The results indicate that the PSO algorithm could determine the optimum combination of f(b) and n(c) that produce the best classification accuracy of the MLP.
    Matched MeSH terms: Sound Spectrography/methods*
  11. Knowledge based system with embedded intelligent heart sound analyser for diagnosing cardiovascular disorders
    Javed F, Venkatachalam PA, Hani AF
    J Med Eng Technol, 2007 Sep-Oct;31(5):341-50.
    PMID: 17701779 DOI: 10.1080/03091900600887876
    Cardiovascular disease (CVD) is the leading cause of death worldwide, and due to the lack of early detection techniques, the incidence of CVD is increasing day by day. In order to address this limitation, a knowledge based system with embedded intelligent heart sound analyser (KBHSA) has been developed to diagnose cardiovascular disorders at early stages. The system analyses digitized heart sounds that are recorded from an electronic stethoscope using advanced digital signal processing and artificial intelligence techniques. KBHSA takes into account data including the patient's personal and past medical history, clinical examination, auscultation findings, chest x-ray and echocardiogram, and provides a list of diseases that it has diagnosed. The system can assist the general physician in making more accurate and reliable diagnosis under emergency conditions where expert cardiologists and advanced equipment are not readily available. To test the validity of the system, abnormal heart sound samples and medical data from 40 patients were recorded and analysed. The diagnoses made by the system were counter checked by four senior cardiologists in Malaysia. The results show that the findings of KBHSA coincide with those of cardiologists.
    Matched MeSH terms: Sound Spectrography/methods*
  12. Fulltext Sound signatures and production mechanisms of three species of pipefishes (Family: Syngnathidae)
    Lim AC, Chong VC, Wong CS, Muniandy SV
    PeerJ, 2015;3:e1471.
    PMID: 26734507 DOI: 10.7717/peerj.1471
    Background. Syngnathid fishes produce three kinds of sounds, named click, growl and purr. These sounds are generated by different mechanisms to give a consistent signal pattern or signature which is believed to play a role in intraspecific and interspecific communication. Commonly known sounds are produced when the fish feeds (click, purr) or is under duress (growl). While there are more acoustic studies on seahorses, pipefishes have not received much attention. Here we document the differences in feeding click signals between three species of pipefishes and relate them to cranial morphology and kinesis, or the sound-producing mechanism. Methods. The feeding clicks of two species of freshwater pipefishes, Doryichthys martensii and Doryichthys deokhathoides and one species of estuarine pipefish, Syngnathoides biaculeatus, were recorded by a hydrophone in acoustic dampened tanks. The acoustic signals were analysed using time-scale distribution (or scalogram) based on wavelet transform. A detailed time-varying analysis of the spectral contents of the localized acoustic signal was obtained by jointly interpreting the oscillogram, scalogram and power spectrum. The heads of both Doryichthys species were prepared for microtomographical scans which were analysed using a 3D imaging software. Additionally, the cranial bones of all three species were examined using a clearing and double-staining method for histological studies. Results. The sound characteristics of the feeding click of the pipefish is species-specific, appearing to be dependent on three bones: the supraoccipital, 1st postcranial plate and 2nd postcranial plate. The sounds are generated when the head of the Dorichthyes pipefishes flexes backward during the feeding strike, as the supraoccipital slides backwards, striking and pushing the 1st postcranial plate against (and striking) the 2nd postcranial plate. In the Syngnathoides pipefish, in the absence of the 1st postcranial plate, the supraoccipital rubs against the 2nd postcranial plate twice as it is pulled backward and released on the return. Cranial morphology and kinesis produce acoustic signals consistent with the bone strikes that produce sharp energy spikes (discrete or merged), or stridulations between bones that produce repeated or multimodal sinusoidal waveforms. Discussion. The variable structure of the sound-producing mechanism explains the unique acoustic signatures of the three species of pipefish. The differences in cranial bone morphology, cranial kinesis and acoustic signatures among pipefishes (and seahorses) could be attributed to independent evolution within the Syngnathidae, which warrants further investigation.
    Matched MeSH terms: Sound
  13. Fulltext Condition assessment of PC tendon duct filling by elastic wave velocity mapping
    Liu KF, Chai HK, Mehrabi N, Yoshikazu K, Shiotani T
    ScientificWorldJournal, 2014;2014:194295.
    PMID: 24737961 DOI: 10.1155/2014/194295
    Imaging techniques are high in demand for modern nondestructive evaluation of large-scale concrete structures. The travel-time tomography (TTT) technique, which is based on the principle of mapping the change of propagation velocity of transient elastic waves in a measured object, has found increasing application for assessing in situ concrete structures. The primary aim of this technique is to detect defects that exist in a structure. The TTT technique can offer an effective means for assessing tendon duct filling of prestressed concrete (PC) elements. This study is aimed at clarifying some of the issues pertaining to the reliability of the technique for this purpose, such as sensor arrangement, model, meshing, type of tendon sheath, thickness of sheath, and material type as well as the scale of inhomogeneity. The work involved 2D simulations of wave motions, signal processing to extract travel time of waves, and tomography reconstruction computation for velocity mapping of defect in tendon duct.
    Matched MeSH terms: Sound
  14. Fulltext Hawkmoths produce anti-bat ultrasound
    Barber JR, Kawahara AY
    Biol Lett, 2013 Aug 23;9(4):20130161.
    PMID: 23825084 DOI: 10.1098/rsbl.2013.0161
    Bats and moths have been engaged in aerial warfare for nearly 65 Myr. This arms race has produced a suite of counter-adaptations in moths, including bat-detecting ears. One set of defensive strategies involves the active production of sound; tiger moths' ultrasonic replies to bat attack have been shown to startle bats, warn the predators of bad taste and jam their biosonar. Here, we report that hawkmoths in the Choerocampina produce entirely ultrasonic sounds in response to tactile stimulation and the playback of biosonar attack sequences. Males do so by grating modified scraper scales on the outer surface of the genital valves against the inner margin of the last abdominal tergum. Preliminary data indicate that females also produce ultrasound to touch and playback of echolocation attack, but they do so with an entirely different mechanism. The anti-bat function of these sounds is unknown but might include startling, cross-family acoustic mimicry, warning of unprofitability or physical defence and/or jamming of echolocation. Hawkmoths present a novel and tractable system to study both the function and evolution of anti-bat defences.
    Matched MeSH terms: Sound
  15. Fulltext Smart Walk Stick for Visually Impaired People: Design and Implementation
    Saud, Safaa Najah, Manivannan, Dasarataan, Adzliza Binti Salmi, Lilysuriazna Raya
    Journal of Management & Science, 2018;16(2):19-28.
    MyJurnal
    Nowadays, the scientific knowledge is developing frequently in numerous characteristics to be able to offer versatile and also safe and sound tendency for the users. At this time many of prevalent together with employed indicate by the visually impaired people are using the ivory stick, nonetheless it possesses constraints. With the recent technological innovation, it is easy to prolong the assistance acquire for people who have visual disability throughout their movability; this design endorses a cost-effective ultrasonic stick for visually encountered people today, to be able to achieve an exclusive self-reliance and even exempt from the additional assist. A portable convenient to use technology is designed which could recognize the obstructions in the way working with ultrasonic sensors in addition to vibrator. Ultrasonic sensors will be able to inspect three types of distinct heights. Vibrator is frequently used as a substitute gadget in the areas that surrounds with the minimal signal coverage also nosy environment. The buzzer and vibration motor are initialized while any kind of hindrance is identified. Global positioning system device presents the details about to the proceeding approach both work or even home, that has been supplied considering that control keys together with a contingency switch. Text message unit is utilized by the blind to send out SMS info to the saved phone numbers in the Arduino in the event of unexpected emergency.

    Matched MeSH terms: Sound
  16. Fulltext Development of a Novel Design and Subsequent Fabrication of an Automated Touchless Hand Sanitizer Dispenser to Reduce the Spread of Contagious Diseases
    Das A, Barua A, Mohimin MA, Abedin J, Khandaker MU, Al-Mugren KS
    Healthcare (Basel), 2021 Apr 10;9(4).
    PMID: 33920290 DOI: 10.3390/healthcare9040445
    BACKGROUND: The use of a touchless automated hand sanitizer dispenser may play a key role to reduce contagious diseases. The key problem of the conventional ultrasonic and infra-red-based dispensers is their malfunctioning due to the interference of sunlight, vehicle sound, etc. when deployed in busy public places. To overcome such limitations, this study introduced a laser-based sensing device to dispense sanitizer in an automated touchless process.

    METHOD: The dispensing system is based on an Arduino circuit breadboard where an ATmega328p microcontroller was pre-installed. To sense the proximity, a light-dependent resistor (LDR) is used where the laser light is to be blocked after the placement of human hands, hence produced a sharp decrease in the LDR sensor value. Once the LDR sensor value exceeds the lower threshold, the pump is actuated by the microcontroller, and the sanitizer dispenses through the nozzle.

    RESULTS AND DISCUSSION: A novel design and subsequent fabrication of a low-cost, touchless, automated sanitizer dispenser to be used in public places, was demonstrated. The overall performance of the manufactured device was analyzed based on the cost and power consumption, and environmental factors by deploying it in busy public places as well as in indoor environment in major cities in Bangladesh, and found to be more efficient and cost-effective compared to other dispensers available in the market. A comprehensive discussion on this unique design compared to the conventional ultrasonic and infra-red based dispensers, is presented to show its suitability over the commercial ones. The guidelines of the World Health Organization are followed for the preparation of sanitizer liquid. A clear demonstration of the circuitry connections is presented herein, which facilitates the interested individual to manufacture a cost-effective dispenser device in a relatively short time and use it accordingly. Conclusion: This study reveals that the LDR-based automated hand sanitizer dispenser system is a novel concept, and it is cost-effective compared to the conventional ones. The presented device is expected to play a key role in contactless hand disinfection in public places, and reduce the spread of infectious diseases in society.

    Matched MeSH terms: Sound
  17. Fulltext Noise characteristics of grass-trimming machine engines and their effect on operators
    Mallick Z, Badruddin IA, Khaleed Hussain MT, Salman Ahmed NJ, Kanesan J
    Noise Health, 2009 Apr-Jun;11(43):98-102.
    PMID: 19414929 DOI: 10.4103/1463-1741.50694
    Over the last few years, interaction of humans with noisy power-driven agricultural tools and its possible adverse after effects have been realized. Grass-trimmer engine is the primary source of noise and the use of motorized cutter, spinning at high speed, is the secondary source of noise to which operators are exposed. In the present study, investigation was carried out to determine the effect of two types of grass-trimming machine engines (SUM 328 SE and BG 328) noise on the operators in real working environment. It was found that BG-328 and SUM-328 SE produced high levels of noise, of the order of 100 and 105 dB(A), respectively, to which operators are exposed while working. It was also observed that situation aggravates when a number of operators simultaneously operate resulting in still higher levels of noise. Operators should be separated 15 meters from each other in order to avoid the combined level of noise exposure while working with these machines. It was found that SPL, of the grass-trimmer machine engines (BG-328 and SUM-328 SE), were higher than the limit of noise recommended by ISO, NIOSH, and OSHA for an 8-hour workday. Such a high level of noise exposure may cause physiological and psychological problems to the operators in long run.
    Matched MeSH terms: Sound Spectrography
  18. Fulltext Small scale imaging using ultrasonic tomography
    Zakaria, Z., Fazalul Rahiman, M.H., Abdul Rahim, R., Megat Ali, M.S.A., Baharuddin, M.Y., Jahidin, A.H.
    Journal of Nuclear and Related Technologies, 2009;2009(1):266-281.
    MyJurnal
    Ultrasound technology progressed through the 1960’s from simple A-mode and B-mode scans to today’s M-mode and Doppler two dimensional (2-D) and even three dimensional (3-D) systems. Modern ultrasound imaging has its roots in sonar technology after it was first described by Lord John Rayleigh over 100 years ago on the interaction of acoustic waves with media. Tomography technique was developed as a diagnostic tool in the medical area since the early of 1970’s. This research initially focused on how to retrieve a cross sectional images from living or non-living things. After a decade, the application of tomography systems span into the industrial area. However, the long exposure time of medical radiation-based method cannot tolerate the dynamic changes in industrial process two phase liquid/gas flow system.. An alternative system such as a process tomography system, can give information on the nature of the flow regime characteristic. The overall aim of this paper is to investigate the use of a small scale ultrasonic tomography method based on ultrasonic transmission mode tomography for online monitoring of liquid/gas flow in pipe/vessel system through ultrasonic transceivers application. This non-invasive technique applied sixteen transceivers as the sensing elements to cover the pipe/vessel cross section. The paper also details the transceivers selection criteria, hardware setup, the electronic measurement circuit and also the image reconstruction algorithm applied. The system was found capable of visualizing the internal characteristics and provides the concentration profile for the corresponding liquid and gas phases.
    Matched MeSH terms: Sound
  19. Fulltext Linguistic context effects in the speech perfection of Malay-speaking normal hearing young adults
    Cila Umat, Nahazatul Islia Jamari
    Jurnal Sains Kesihatan Malaysia, 2006;4(1):9-20.
    MyJurnal
    The study examined the use of linguistic contextual cues among native, Malay-speaking normal hearing young adults. Ten undergraduate students of Universiti Kebangsaan Malaysia participated in the study. All subjects had normal hearing with the average hearing threshold levels for the overall left and the right ears of 7.8 dB (SD 4.1). The Malay Hearing in Noise Test (MyHINT) materials were employed and presented to the subjects at an approximately 65 dBA presentation level. Testing was conducted in a sound field in three different listening conditions: in quiet, in noise with +5 dB signal-to-noise ratio (SNR) and 0 dB SNR. In every test condition, three lists of MyHINT were administered to each subject. The magnitude of context effects was measured using the j factor, which was derived from measurements of recognition probabilities for whole sentences (13,) and the constituent words in the sentences (PP) in which j = log P./ log P P. Results showed that all subjects scored 100% identification of words in sentences and whole sentences in quiet listening condition, while subjects' performances in 0 dB SNR were significantly poorer than that in quiet and in +5 dB SNR (p < 0.001). The j-values were significantly correlated with the probability of recognizing words in the sentences (r = 0.515, p = 0.029) in which lower j values were associated with lower P ps. Subjects were not significantly different from each other in their use of contextual cues in adverse listening conditions [F(9, 7) = 1.34, p = 0.359]. Using the linear regression function for j on word recognition probabilities, the predicted P. were calculated. It was found that the predicted and measured probabilities of recognizing whole sentences were highly correlated: r = 0.973, p < 0.001. The results suggested that linguistic contextual information become increasingly important for recognition of sentences by normal hearing young adult listeners as SNR deteriorates.
    Matched MeSH terms: Sound
  20. Fulltext Assessment of traffic noise and the association with non auditory effect among shop lot workers in Kajang, Selangor
    Mohd Zahiruddin Zukfali, Haliza Abdul Rahman
    Malaysian Journal of Public Health Medicine, 2016;16(10):0-0.
    MyJurnal
    The objective of study is to determine traffic noise level and non-auditory effect among shop lot workers at Kajang Selangor. This cross sectional study was carried to study traffic noise exposure with annoyance and work performance level among shop lot workers in Jalan Mendaling, JalanTukang and Jalan Sulaiman at Kajang town, Selangor. This study involves 120 shop lot workers that exposed to the traffic noise during their working hours where they are randomly selected. Noise exposure was estimated using the Sound Level Meter for environmental noise. The traffic volume was recorded using video recorder and calculated using tally counter. One set questionnaire consist standard questionnaire was used to assess the annoyance level and work performance level among the respondents. Respondents were predominantly by male which are 94 and female, 26 respondents. The mean age of the respondent were ranged between 41 to 60 years old. Only 12.5% of respondent are ranged 21 until 30 years old. In total of 120 respondent, 54.2% of them are Chinese while Malay and India only 30% and 15.8% respectively. The result showed that the traffic noise level at study areas are exceeded the permissible sound limit of commercial and business area during daylight which is 70 dB(A). Regarding work performance, 94 respondents are having low work performance level and 82% of respondent high annoyance level during the exposure of traffic noise from four different sources which are noise from the traffic, speeding vehicle, high traffic volume and exhaust system. There is a significant relationship between traffic noise level with work performance level (p=0.001) and annoyance level (p=0.026). The average traffic noise (Laeq) level at Jalan Mendaling, Jalan Tukang and Jalan Sulaiman is 71.19 dB(A) which were high and exceeds permissible sound level from road traffic, commercial and business place at day time, 70 dB(A). The exposure from the traffic noise effect the annoyance level and work performance level among the shop lot worker. In order to reduce traffic noise exposure towards the shop lot workers, some recommendation are needed to control the traffic noise such as build a noise barrier, plant trees and also enforcement of legal requirement in noise level.
    Matched MeSH terms: Sound
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