Displaying publications 1 - 20 of 72 in total

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  1. Fulltext An analytical model for computing the sound power of an unbraced irregular-shaped plate of variable thickness
    Lee MK, Hosseini Fouladi M, Narayana Namasivayam S
    Sci Rep, 2018 Oct 18;8(1):15355.
    PMID: 30337652 DOI: 10.1038/s41598-018-33645-y
    An irregular-shaped plate with dimensions identical to a guitar soundboard is chosen for this study. It is well known that the classical guitar soundboard is a major contributor to acoustic radiation at high frequencies when compared to the bridge and sound hole. This paper focuses on using an analytical model to compute the sound power of an unbraced irregular-shaped plate of variable thickness up to frequencies of 5 kHz. The analytical model is an equivalent thin rectangular plate of variable thickness. Sound power of an irregular-shaped plate of variable thickness and with dimensions of an unbraced Torres' soundboard is determined from computer analysis using ANSYS. The number of acoustic elements used in ANSYS for accurate simulation is six elements per wavelength. Here we show that the analytical model can be used to compute sound power of an unbraced irregular-shaped plate of variable thickness.
    Matched MeSH terms: Sound
  2. In situ generation of plasma-activated aerosols via surface acoustic wave nebulization for portable spray-based surface bacterial inactivation
    Wong KS, Lim WTH, Ooi CW, Yeo LY, Tan MK
    Lab Chip, 2020 05 19;20(10):1856-1868.
    PMID: 32342089 DOI: 10.1039/d0lc00001a
    The presence of reactive species in plasma-activated water is known to induce oxidative stresses in bacterial species, which can result in their inactivation. By integrating a microfludic chipscale nebulizer driven by surface acoustic waves (SAWs) with a low-temperature atmospheric plasma source, we demonstrate an efficient technique for in situ production and application of plasma-activated aerosols for surface disinfection. Unlike bulk conventional systems wherein the water is separately batch-treated within a container, we show in this work the first demonstration of continuous plasma-treatment of water as it is transported through a paper strip from a reservoir onto the chipscale SAW device. The significantly larger surface area to volume ratio of the water within the paper strip leads to a significant reduction in the duration of the plasma-treatment, while maintaining the concentration of the reactive species. The subsequent nebulization of the plasma-activated water by the SAW then allows the generation of plasma-activated aerosols, which can be directly sprayed onto the contaminated surface, therefore eliminating the storage of the plasma-activated water and hence circumventing the typical limitation in conventional systems wherein the concentration of the reactive species diminishes over time during storage, resulting in a reduction in the efficacy of bacterial inactivation. In particular, we show up to 96% reduction in Escherichia coli colonies through direct spraying with the plasma-activated aerosols. This novel, low-cost, portable and energy-efficient hybrid system necessitates only minimal maintenance as it only requires the supply of tap water and battery power for operation, and is thus suitable for decontamination in home environments.
    Matched MeSH terms: Sound*
  3. Beamforming technique for investigation of lateral variability at geotechnical sites
    Norfarah Nadia Ismail, Joh SH, Raja Hassanul Musa Raja Ahmad
    Sains Malaysiana, 2012;41:1621-1627.
    A beamformer in seismology is a signal receptor with a series of geophones, in which a beam of elastic waves is formed like a light beam by adjusting signal delays at individual geophones. Recently, beamforming has extended its applications to surface-wave measurement. In surface-wave measurement, beamforming provides unique advantages over other surface-wave methods, such as full automation in data analysis as well as directional signal reception to minimize scattered noise and multiple reflections in signals. However, certain defects depreciate the value of beamforming in terms of its practicality and feasibility. These include the requirement of having many receivers and the loss of small wavelength data due to spatial aliasing. It leads to insensitivity in identification of lateral variability, which creates the problem of having to smooth out geologic features and complexities like folding, faults and fractures. In this paper, advances in the refinement of beamforming were described on two counts: improvement of sensitivity in identification of lateral variability and recovery of aliased wave numbers, which enables evaluation of shallow material. On the passage to refinement, synthetic waveforms for typical layering systems were generated to figure out characteristics of beamformer velocities in comparison with SASW velocities and theoretical normal-mode velocities.
    Matched MeSH terms: Sound
  4. Fulltext A Facile and Flexible Method for On-Demand Directional Speed Tunability in the Miniaturised Lab-on-a-Disc
    Tan MK, Siddiqi A, Yeo LY
    Sci Rep, 2017 07 27;7(1):6652.
    PMID: 28751783 DOI: 10.1038/s41598-017-07025-x
    The Miniaturised Lab-on-a-Disc (miniLOAD) platform, which utilises surface acoustic waves (SAWs) to drive the rotation of thin millimeter-scale discs on which microchannels can be fabricated and hence microfluidic operations can be performed, offers the possibility of miniaturising its larger counterpart, the Lab-on-a-CD, for true portability in point-of-care applications. A significant limitation of the original miniLOAD concept, however, is that it does not allow for flexible control over the disc rotation direction and speed without manual adjustment of the disc's position, or the use of multiple devices to alter the SAW frequency. In this work, we demonstrate the possibility of achieving such control with the use of tapered interdigitated transducers to confine a SAW beam such that the localised acoustic streaming it generates imparts a force, through hydrodynamic shear, at a specific location on the disc. Varying the torque that arises as a consequence by altering the input frequency to the transducers then allows the rotational velocity and direction of the disc to be controlled with ease. We derive a simple predictive model to illustrate the principle by which this occurs, which we find agrees well with the experimental measurements.
    Matched MeSH terms: Sound; Sound Localization
  5. Fulltext Investigation into mass loading sensitivity of sezawa wave mode-based surface acoustic wave sensors
    Mohanan AA, Islam MS, Ali SH, Parthiban R, Ramakrishnan N
    Sensors (Basel), 2013;13(2):2164-75.
    PMID: 23389346 DOI: 10.3390/s130202164
    In this work mass loading sensitivity of a Sezawa wave mode based surface acoustic wave (SAW) device is investigated through finite element method (FEM) simulation and the prospects of these devices to function as highly sensitive SAW sensors is reported. A ZnO/Si layered SAW resonator is considered for the simulation study. Initially the occurrence of Sezawa wave mode and displacement amplitude of the Rayleigh and Sezawa wave mode is studied for lower ZnO film thickness. Further, a thin film made of an arbitrary material is coated over the ZnO surface and the resonance frequency shift caused by mass loading of the film is estimated. It was observed that Sezawa wave mode shows significant sensitivity to change in mass loading and has higher sensitivity (eight times higher) than Rayleigh wave mode for the same device configuration. Further, the mass loading sensitivity was observed to be greater for a low ZnO film thickness to wavelength ratio. Accordingly, highly sensitive SAW sensors can be developed by coating a sensing medium over a layered SAW device and operating at Sezawa mode resonance frequency. The sensitivity can be increased by tuning the ZnO film thickness to wavelength ratio.
    Matched MeSH terms: Sound
  6. Fulltext Pathophysiology of Subjective Tinnitus: Triggers and Maintenance
    Haider HF, Bojić T, Ribeiro SF, Paço J, Hall DA, Szczepek AJ
    Front Neurosci, 2018;12:866.
    PMID: 30538616 DOI: 10.3389/fnins.2018.00866
    Tinnitus is the conscious perception of a sound without a corresponding external acoustic stimulus, usually described as a phantom perception. One of the major challenges for tinnitus research is to understand the pathophysiological mechanisms triggering and maintaining the symptoms, especially for subjective chronic tinnitus. Our objective was to synthesize the published literature in order to provide a comprehensive update on theoretical and experimental advances and to identify further research and clinical directions. We performed literature searches in three electronic databases, complemented by scanning reference lists from relevant reviews in our included records, citation searching of the included articles using Web of Science, and manual searching of the last 6 months of principal otology journals. One-hundred and thirty-two records were included in the review and the information related to peripheral and central mechanisms of tinnitus pathophysiology was collected in order to update on theories and models. A narrative synthesis examined the main themes arising from this information. Tinnitus pathophysiology is complex and multifactorial, involving the auditory and non-auditory systems. Recent theories assume the necessary involvement of extra-auditory brain regions for tinnitus to reach consciousness. Tinnitus engages multiple active dynamic and overlapping networks. We conclude that advancing knowledge concerning the origin and maintenance of specific tinnitus subtypes origin and maintenance mechanisms is of paramount importance for identifying adequate treatment.
    Matched MeSH terms: Sound
  7. Fulltext Time frequency analysis of peking gamelan
    Sinin Hamdan, Iran Amri Musoddiq, Ahmad Fauzi Musib, Marini Sawawi
    Pertanika Journal of Science & Technology, 2020;28(2):441-457.
    MyJurnal
    The tone of peking 1, 2, 3, 5, 6, 1’ was investigated using time-frequency analysis (TFA). The frequencies were measured using PicoScope oscilloscope, Melda analyzer in Cubase version 9 and Adobe version 3. Three different approaches for time-frequency analysis were used: Fourier spectra (using PicoScope), spectromorphology (using Melda analyzer) and spectrograms (using Adobe). Fourier spectra only identify intensity-frequency within entire signals, while spectromorphology identify the changes of intensity-frequency spectrum at fixed time and Adobe spectrograms identify the frequency with time. PicoScope reading produces the spectra of the fundamental and overtone frequencies in the entire sound. These overtones are non-harmonic since they are non-integral multiples of the fundamental. The fundamental frequencies of peking 1, 2, 3, 5, 6 were 1066Hz (C6), 1178Hz (D6), 1342Hz (E6), 1599Hz (G6) and 1793Hz (A6) respectively while peking 1’was 2123Hz (C7) i.e. one octave higher than peking 1. Melda analyzer reading proved that all peking sustained the initial fundamental frequency and overtone at t=0 until 2s. TFA from Adobe reading provides a description of the sound in the time-frequency plane. From TFA, peking 1, 2 and 6 exhibited a much gentler attack and more rapid decay than peking 3, 5 and 1’.
    Matched MeSH terms: Sound
  8. Fulltext Timbre spectrum of gamelan instruments from four Malay gamelan ensembles
    Hamdan, Sinin, Ahmad Faudzi Musib, Musoddiq, Iran Amri, Marini Sawawi
    Pertanika Journal of Science & Technology, 2020;28(2):459-476.
    MyJurnal
    Gamelan in general is categorized as a group of gongs. This traditional Malay gamelan ensemble is in a slendro scale i.e. five notes per octave. The rhythms, pitch, duration and loudness classify the various groups of gongs such as bonang, kenong, gender, peking and gambang. The cast bronze peking, kenong and bonang were chosen from a range of Malay gamelan ensemble from Universiti Malaysia Sarawak (UNIMAS), Universiti Putra Malaysia (UPM), Universiti Kebangsaan Malaysia (UKM) and Universiti Teknologi Mara (UiTM). The sounds were recorded by PicoScope Oscilloscope. The PicoScope software displays waveform and spectrum in time and frequency domain respectively. The peking lowest and highest frequencies from UiTM were 293 Hz and 1867 Hz, from UPM were 644 Hz and 1369 Hz, from UKM were 1064 Hz and 2131 Hz and from UNIMAS were 1072 Hz and 2105 Hz respectively. The kenong lowest and highest frequencies from UiTM were 259 Hz and 463 Hz, from UPM were 294 Hz and 543 Hz, from UKM were 300 Hz and 540 Hz and from UNIMAS were 293 Hz and 519 Hz respectively. The fundamental frequencies of bonang from UPM were higher than that of UKM, UiTM and UNIMAS. The harmonics were not successive but interrupted by another frequency. The harmonics of each bonang was similar except for gamelan from UKM.
    Matched MeSH terms: Sound
  9. Enhancing greywater treatment via MHz-Order surface acoustic waves
    Chan JS, Poh PE, Ismadi MP, Yeo LY, Tan MK
    Water Res, 2020 Feb 01;169:115187.
    PMID: 31671294 DOI: 10.1016/j.watres.2019.115187
    There is a pressing need for efficient biological treatment systems for the removal of organic compounds in greywater given the rapid increase in household wastewater produced as a consequence of rapid urbanisation. Moreover, proper treatment of greywater allows its reuse that can significantly reduce the demand for freshwater supplies. Herein, we demonstrate the possibility of enhancing the removal efficiency of solid contaminants from greywater using MHz-order surface acoustic waves (SAWs). A key distinction of the use of these high frequency surface acoustic waves, compared to previous work on its lower frequency (kHz order) bulk ultrasound counterpart for wastewater treatment, is the absence of cavitation, which can inflict considerable damage on bacteria, thus limiting the intensity and duration, and hence the efficiency enhancement, associated with the acoustic exposure. In particular, we show that up to fivefold improvement in the removal efficiency can be obtained, primarily due to the ability of the acoustic pressure field in homogenizing and reducing the size of bacterial clusters in the sample, therefore providing a larger surface area that promotes greater bacteria digestion. Alternatively, the SAW exposure allows the reduction in the treatment duration to achieve a given level of removal efficiency, thus facilitating higher treatment rates and hence processing throughput. Given the low-cost of the miniature chipscale platform, these promising results highlight its possibility for portable greywater treatment for domestic use or for large-scale industrial wastewater processing through massive parallelization.
    Matched MeSH terms: Sound
  10. Acoustially-mediated microfluidic nanofiltration through graphene films
    Ang KM, Yeo LY, Hung YM, Tan MK
    Nanoscale, 2017 May 18;9(19):6497-6508.
    PMID: 28466906 DOI: 10.1039/c7nr01690e
    We exploit the possibility of enhancing the molecular transport of liquids through graphene films using amplitude modulated surface acoustic waves (SAWs) to demonstrate effective and efficient nanoparticle filtration. The use of the SAW, which is an extremely efficient means for driving microfluidic transport, overcomes the need for the large mechanical pumps required to circumvent the large pressure drops encountered in conventional membranes for nanoparticle filtration. 100% filtration efficiency was obtained for micron-dimension particulates, decreasing to only 95% for the filtration of particles of tens of nanometers in dimension, which is comparable to that achieved with other methods. To circumvent clogging of the film, which is typical with all membrane filters, a backwash operation to flush the nanoparticles is incorporated simply by reversing the SAW-induced flow such that 98% recovery of the initial filtration rate is recovered. Given these efficiencies, together with the low cost and compact size of the chipscale SAW devices, we envisage the possibility of scaling out the process by operating a large number of devices in parallel to achieve typical industrial-scale throughputs with potential benefits in terms of substantially lower capital, operating and maintenance costs.
    Matched MeSH terms: Sound
  11. Fulltext Relevance of integrated geophysical methods for site characterization in construction industry - a case of Apa in Badagry, Lagos State, Nigeria
    Ishola, K. S., Adeoti, L., Sawyerr, F., Adiat, K. A. N
    Pertanika Journal of Science & Technology, 2014;22(2):507-527.
    MyJurnal
    Detailed geophysical investigations have been carried out using integrated geophysical methods with a view to characterising the subsurface lithologic features that might indicate suitable places for structural developments. An overview of the subsurface resistivity distribution has been achieved employing 8Vertical Electrical Soundings with the Schlumberger array and 4 2D resistivity imaging using Wenner array. In order to constrain the results of the electrical resistivity methods, we carried out a ground magnetic survey along E-W direction using the Proton precession magnetometer at 1m sampling interval. Analysis of well logs data available and VES results showed 4 to 5 geoelectric layers corresponding to sand, clayey sand, clay, silty sand and sandy clay. The 2D resistivity imaging sections showed relative decrease of apparent resistivity with depth implying a geological transition from sand with high resistivity value of about 508Ωm to clay with low resistivity value 16Ωm at depths of 0-20m and 25-50m respectively. The magnetic profiles showed that the study area was characterised by short wavelengths and amplitudes ranging from –3800 to 700 nT. The highs and lows of the magnetic responses occasioned by lithological variations and structural features were magnetically resolved. In view of the identified subsurface structures, the suggested depth to the competent layer is about 20m for low to medium structures while above 50m would be suitable for heavy or massive engineering structures. The use of integrated geophysical methods for the delineation, identification and imaging of the subsurface geological structures which could provide clues to the nature and type of foundation suitable for the development of the study area has been successfully achieved.
    Matched MeSH terms: Sound
  12. Laboratory study of acoustic velocity in different types of rocks at seismic frequency band
    Suping Peng, Wenfeng Du, Xiaoming Tang, Zeng Hu, Yunlan He
    Sains Malaysiana, 2017;46:2187-2193.
    In order to understand the characteristics of acoustic wave propagation in rocks within seismic frequency band (<100
    Hz), the velocities of longitudinal and transverse waves of four different types of rocks were tested using low-frequency
    stress-strain method by means of the physical testing system of rock at low frequency and the experimental data of acoustic
    velocities of four different types of rocks at this frequency band were obtained. The experimental results showed that the
    acoustic velocities of four different types of rocks increased with the increase of temperature and pressure within the
    temperature and pressure ranges set by the experiment. The acoustic velocity of fine sandstone at 50% water saturation
    was smaller than that of dry sample. The acoustic velocities of four different types of rocks were different and the velocities
    of longitudinal waves of gritstone, fine sandstone, argillaceous siltstone and mudstone increased in turn under similar
    conditions and were smaller than those at ultrasonic frequency. Few of existing studies focus on the acoustic velocity at
    seismic frequency band, thus, further understanding of the acoustic characteristics at this seismic frequency band still
    requires more experimental data.
    Matched MeSH terms: Sound
  13. Fulltext Development of a Tomography Technique for Assessment of the Material Condition of Concrete Using Optimized Elastic Wave Parameters
    Chai HK, Liu KF, Behnia A, Yoshikazu K, Shiotani T
    Materials (Basel), 2016 Apr 16;9(4).
    PMID: 28773416 DOI: 10.3390/ma9040291
    Concrete is the most ubiquitous construction material. Apart from the fresh and early age properties of concrete material, its condition during the structure life span affects the overall structural performance. Therefore, development of techniques such as non-destructive testing which enable the investigation of the material condition, are in great demand. Tomography technique has become an increasingly popular non-destructive evaluation technique for civil engineers to assess the condition of concrete structures. In the present study, this technique is investigated by developing reconstruction procedures utilizing different parameters of elastic waves, namely the travel time, wave amplitude, wave frequency, and Q-value. In the development of algorithms, a ray tracing feature was adopted to take into account the actual non-linear propagation of elastic waves in concrete containing defects. Numerical simulation accompanied by experimental verifications of wave motion were conducted to obtain wave propagation profiles in concrete containing honeycomb as a defect and in assessing the tendon duct filling of pre-stressed concrete (PC) elements. The detection of defects by the developed tomography reconstruction procedures was evaluated and discussed.
    Matched MeSH terms: Sound
  14. Effect of constraint-induced music therapy in idiopathic sudden sensorineural hearing loss: A systematic review and meta-analysis
    Vasiwala RA, Elhariri SY, Teng CL, Mohamad I
    Noise Health, 2022;24(113):75-81.
    PMID: 35900392 DOI: 10.4103/nah.nah_33_21
    BACKGROUND: Idiopathic sudden sensorineural hearing loss (ISSNHL) is commonly encountered in audiologic and otolaryngologic practice. Constraint-induced music/sound therapy (CIMT) is characterized by the plugging of the normal ear (constraint) and the simultaneous, stimulation of the affected ear with music, which is based on a well-established neurorehabilitation approach. Corticosteroid therapy (CST) is the current mainstay of treatment. The prognosis for hearing recovery depends on many factors including the severity of hearing loss, age, and presence of vertigo.

    OBJECTIVE: To analyze the effectiveness of CIMT with CST in ISSNHL.

    METHODS: We performed a systematic search, using specific keywords relevant to our study, in PubMed, Cochrane Central Register of Controlled Trials, and additional sources of published trials till December 2020. We then screened all search results obtained according to our inclusion/exclusion criteria and performed a quality assessment on all studies using the Newcastle-Ottawa scale and using MedCalc, a meta-analysis was performed on suitable studies.

    RESULTS: The recovery rates of three included nonrandomized studies were assessed at 1 to 3 months. A total of 229 (CST: 131, CST + CIMT: 98) patients were pooled for meta-analysis. The meta-analysis using the random-effect model found the relative risk of recovery rate within 3 months to be 1.213 (95% confidence interval 0.709-2.074), a result that is not statistically significant.

    CONCLUSION: Although our analysis results do not demonstrate the noticeable effect of CIMT in ISSNHL, it can support be a gainful adjunct to CST for better hearing results than CST alone. Therefore, it needs further prospective randomized controlled multicenter trials with a large sample.

    Matched MeSH terms: Sound
  15. Fulltext Influence of MHz-order acoustic waves on bacterial suspensions
    Chew NSL, Ooi CW, Yeo LY, Tan MK
    Ultrasonics, 2024 Mar;138:107234.
    PMID: 38171227 DOI: 10.1016/j.ultras.2023.107234
    The development of alternative techniques to efficiently inactivate bacterial suspensions is crucial to prevent transmission of waterborne illness, particularly when commonly used techniques such as heating, filtration, chlorination, or ultraviolet treatment are not practical or feasible. We examine the effect of MHz-order acoustic wave irradiation in the form of surface acoustic waves (SAWs) on Gram-positive (Escherichia coli) and Gram-negative (Brevibacillus borstelensis and Staphylococcus aureus) bacteria suspended in water droplets. A significant increase in the relative bacterial load reduction of colony-forming units (up to 74%) can be achieved by either increasing (1) the excitation power, or, (2) the acoustic treatment duration, which we attributed to the effect of the acoustic radiation force exerted on the bacteria. Consequently, by increasing the maximum pressure amplitude via a hybrid modulation scheme involving a combination of amplitude and pulse-width modulation, we observe that the bacterial inactivation efficiency can be further increased by approximately 14%. By combining this scalable acoustic-based bacterial inactivation platform with plasma-activated water, a 100% reduction in E. coli is observed in less than 10 mins, therefore demonstrating the potential of the synergistic effects of MHz-order acoustic irradiation and plasma-activated water as an efficient strategy for water decontamination.
    Matched MeSH terms: Sound
  16. Fulltext Acoustic emission monitoring of multicell reinforced concrete box girders subjected to torsion
    Bagherifaez M, Behnia A, Majeed AA, Hwa Kian C
    ScientificWorldJournal, 2014;2014:567619.
    PMID: 25180203 DOI: 10.1155/2014/567619
    Reinforced concrete (RC) box girders are a common structural member for road bridges in modern construction. The hollow cross-section of a box girder is ideal in carrying eccentric loads or torques introduced by skew supports. This study employed acoustic emission (AE) monitoring on multicell RC box girder specimens subjected to laboratory-based torsion loading. Three multicell box girder specimens with different cross-sections were tested. The aim is to acquire AE analysis data indicative for characterizing torsion fracture in the box girders. It was demonstrated through appropriate parametric analysis that the AE technique could be utilized to effectively classify fracture developed in the specimens for describing their mechanical behavior under torsion. AE events localization was presented to illustrate the trend of crack and damage propagation in different stages of fracture. It could be observed that spiral-like patterns of crack were captured through AE damage localization system and damage was quantified successfully in different stages of fracture by using smoothed b-value analysis.
    Matched MeSH terms: Sound*
  17. Fulltext Characterisation of structure-borne sound source using reception plate method
    Putra A, Saari NF, Bakri H, Ramlan R, Dan RM
    ScientificWorldJournal, 2013;2013:742853.
    PMID: 24324380 DOI: 10.1155/2013/742853
    A laboratory-based experiment procedure of reception plate method for structure-borne sound source characterisation is reported in this paper. The method uses the assumption that the input power from the source installed on the plate is equal to the power dissipated by the plate. In this experiment, rectangular plates having high and low mobility relative to that of the source were used as the reception plates and a small electric fan motor was acting as the structure-borne source. The data representing the source characteristics, namely, the free velocity and the source mobility, were obtained and compared with those from direct measurement. Assumptions and constraints employing this method are discussed.
    Matched MeSH terms: Sound Spectrography/methods*
  18. Whistle description of Irrawaddy dolphins (Orcaella brevirostris) in Bay of Brunei, Sarawak, Malaysia
    Muhamad HM, Xu X, Zhang X, Jaaman SA, Muda AM
    J Acoust Soc Am, 2018 05;143(5):2708.
    PMID: 29857727 DOI: 10.1121/1.5036926
    Studies of Irrawaddy dolphins' acoustics assist in understanding the behaviour of the species and thereby conservation of this species. Whistle signals emitted by Irrawaddy dolphin within the Bay of Brunei in Malaysian waters were characterized. A total of 199 whistles were analysed from seven sightings between January and April 2016. Six types of whistles contours named constant, upsweep, downsweep, concave, convex, and sine were detected when the dolphins engaged in traveling, foraging, and socializing activities. The whistle durations ranged between 0.06 and 3.86 s. The minimum frequency recorded was 443 Hz [Mean = 6000 Hz, standard deviation (SD) = 2320 Hz] and the maximum frequency recorded was 16 071 Hz (Mean = 7139 Hz, SD = 2522 Hz). The mean frequency range (F.R.) for the whistles was 1148 Hz (Minimum F.R. = 0 Hz, Maximum F.R. = 4446 Hz; SD = 876 Hz). Whistles in the Bay of Brunei were compared with population recorded from the waters of Matang and Kalimantan. The comparisons showed differences in whistle duration, minimum frequency, start frequency, and number of inflection point. Variation in whistle occurrence and frequency may be associated with surface behaviour, ambient noise, and recording limitation. This will be an important element when planning a monitoring program.
    Matched MeSH terms: Sound Spectrography/methods
  19. Whistles emitted by Indo-Pacific humpback dolphins (Sousa chinensis) in Zhanjiang waters, China
    Dong L, Caruso F, Lin M, Liu M, Gong Z, Dong J, et al.
    J Acoust Soc Am, 2019 06;145(6):3289.
    PMID: 31255103 DOI: 10.1121/1.5110304
    Whistles emitted by Indo-Pacific humpback dolphins in Zhanjiang waters, China, were collected by using autonomous acoustic recorders. A total of 529 whistles with clear contours and signal-to-noise ratio higher than 10 dB were extracted for analysis. The fundamental frequencies and durations of analyzed whistles were in ranges of 1785-21 675 Hz and 30-1973 ms, respectively. Six tonal types were identified: constant, downsweep, upsweep, concave, convex, and sine whistles. Constant type was the most dominant tonal type, accounting for 32.51% of all whistles, followed by sine type, accounting for 19.66% of all whistles. This paper examined 17 whistle parameters, which showed significant differences among the six tonal types. Whistles without inflections, gaps, and stairs accounted for 62.6%, 80.6%, and 68.6% of all whistles, respectively. Significant intraspecific differences in all duration and frequency parameters of dolphin whistles were found between this study and the study in Malaysia. Except for start frequency, maximum frequency and the number of harmonics, all whistle parameters showed significant differences between this study and the study conducted in Sanniang Bay, China. The intraspecific differences in vocalizations for this species may be related to macro-geographic and/or environmental variations among waters, suggesting a potential geographic isolation among populations of Indo-Pacific humpback dolphins.
    Matched MeSH terms: Sound Spectrography/methods
  20. Fulltext Validity and Reliability Aspects of a Newly Developed Questionnaire for Auditory Localization
    Zakaria MN
    J Int Adv Otol, 2019 Apr;15(1):182-183.
    PMID: 30924773 DOI: 10.5152/iao.2019.5959
    Matched MeSH terms: Sound Localization/physiology*
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