Displaying publications 1 - 20 of 191 in total

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  1. Mohd Rizal Hamid, Ahmad Faruq Mohamad Rosli, Manokaran, Kesavan, Siti Shafiqa Shamira Hashin, Nik Mohd Dzarrin Ghifari Azmy, Baba Md Deros, et al.
    MyJurnal
    Awareness of occupational noise and its effects is growing. At No. 11 squadron base, Sukhoi jet was identified as the main culprit of occupational noise that affects not just the employees of the base but also civilian people in the surrounding area. The objective of the study is to identify the noise level produced by Sukhoi two-engines jet during maintenance operations. Investigations were carried out using Bruel & Kjaer 2250 sound level meter hand-analyser. Measurements were performed directly under the Sukhoi jet body and then 10 metres, 50 metres, 100 metres, 1000 metres and 1500 metres away. The jet engines could operate at two levels, at 72% RPM and at 85% RPM. The civilians are only exposed to its noise from more than 1000 metres away. The results from this study are analysed and noise mapping and noise contouring are produced which give the level of noise exposure. The maximum noise is recorded t 122dB(A) and the minimum is at 60dB(A). The farther the noise from the jet is measured, the lower the values recorded. From the noise mapping, the effects of noise exposures on both the employees at the base and the civilian at the neighbouring surrounding could be identified. Even though the exposures are only for 5-10 minutes, it is still considered as a threat
    Matched MeSH terms: Noise, Occupational
  2. Katiri R, Hall DA, Buggy N, Hogan N, Horobin A, van de Heyning P, et al.
    Trials, 2020 Mar 04;21(1):238.
    PMID: 32131880 DOI: 10.1186/s13063-020-4094-9
    BACKGROUND: Single-sided deafness (SSD) describes the presence of a unilateral severe to profound sensorineural hearing loss. SSD disrupts spatial hearing and understanding speech in background noise. It has functional, psychological and social consequences. Potential options for rehabilitation include hearing aids and auditory implants. Benefits and harms of these interventions are documented inconsistently in the literature, using a variety of outcomes ranging from tests of speech perception to quality of life questionnaires. It is therefore difficult to compare interventions when rehabilitating SSD. The Core Rehabilitation Outcome Set for Single Sided Deafness (CROSSSD) study is an international initiative that aims to develop a minimum set of core outcomes for use in future trials of SSD interventions.

    METHODS/DESIGN: The CROSSSD study adopts an international two-round online modified Delphi survey followed by a stakeholder consensus meeting to identify a patient-centred core outcome domain set for SSD based on what is considered critical and important for assessing whether an intervention for SSD has worked.

    DISCUSSION: The resulting core outcome domain set will act as a minimum standard for reporting in future clinical trials and could have further applications in guiding the use of outcome measures in clinical practice. Standardisation will facilitate comparison of research findings.

    Matched MeSH terms: Noise
  3. Hu S, Anschuetz L, Hall DA, Caversaccio M, Wimmer W
    Trends Hear, 2021 3 6;25:2331216520986303.
    PMID: 33663298 DOI: 10.1177/2331216520986303
    Residual inhibition, that is, the temporary suppression of tinnitus loudness after acoustic stimulation, is a frequently observed phenomenon that may have prognostic value for clinical applications. However, it is unclear in which subjects residual inhibition is more likely and how stable the effect of inhibition is over multiple repetitions. The primary aim of this work was to evaluate the effect of hearing loss and tinnitus chronicity on residual inhibition susceptibility. The secondary aim was to investigate the short-term repeatability of residual inhibition. Residual inhibition was assessed in 74 tinnitus subjects with 60-second narrow-band noise stimuli in 10 consecutive trials. The subjects were assigned to groups according to their depth of suppression (substantial residual inhibition vs. comparator group). In addition, a categorization in normal hearing and hearing loss groups, related to the degree of hearing loss at the frequency corresponding to the tinnitus pitch, was made. Logistic regression was used to identify factors associated with susceptibility to residual inhibition. Repeatability of residual inhibition was assessed using mixed-effects ordinal regression including poststimulus time and repetitions as factors. Tinnitus chronicity was not associated with residual inhibition for subjects with hearing loss, while a statistically significant negative association between tinnitus chronicity and residual inhibition susceptibility was observed in normal hearing subjects (odds ratio: 0.63; p = .0076). Moreover, repeated states of suppression can be stably induced, reinforcing the use of residual inhibition for within-subject comparison studies.
    Matched MeSH terms: Noise
  4. Guest H, Dewey RS, Plack CJ, Couth S, Prendergast G, Bakay W, et al.
    Trends Hear, 2018;22:2331216518803213.
    PMID: 30295145 DOI: 10.1177/2331216518803213
    Lifetime noise exposure is generally quantified by self-report. The accuracy of retrospective self-report is limited by respondent recall but is also bound to be influenced by reporting procedures. Such procedures are of variable quality in current measures of lifetime noise exposure, and off-the-shelf instruments are not readily available. The Noise Exposure Structured Interview (NESI) represents an attempt to draw together some of the stronger elements of existing procedures and to provide solutions to their outstanding limitations. Reporting is not restricted to prespecified exposure activities and instead encompasses all activities that the respondent has experienced as noisy (defined based on sound level estimated from vocal effort). Changing exposure habits over time are reported by dividing the lifespan into discrete periods in which exposure habits were approximately stable, with life milestones used to aid recall. Exposure duration, sound level, and use of hearing protection are reported for each life period separately. Simple-to-follow methods are provided for the estimation of free-field sound level, the sound level emitted by personal listening devices, and the attenuation provided by hearing protective equipment. An energy-based means of combining the resulting data is supplied, along with a primarily energy-based method for incorporating firearm-noise exposure. Finally, the NESI acknowledges the need of some users to tailor the procedures; this flexibility is afforded, and reasonable modifications are described. Competency needs of new users are addressed through detailed interview instructions (including troubleshooting tips) and a demonstration video. Limited evaluation data are available, and future efforts at evaluation are proposed.
    Matched MeSH terms: Hearing Loss, Noise-Induced/diagnosis*; Hearing Loss, Noise-Induced/epidemiology*; Noise, Occupational/adverse effects*
  5. Akbari M, Manesh MR, El-Saleh AA, Reza AW
    ScientificWorldJournal, 2014;2014:128195.
    PMID: 25045725 DOI: 10.1155/2014/128195
    In diversity combining at the receiver, the output signal-to-noise ratio (SNR) is often maximized by using the maximal ratio combining (MRC) provided that the channel is perfectly estimated at the receiver. However, channel estimation is rarely perfect in practice, which results in deteriorating the system performance. In this paper, an imperialistic competitive algorithm (ICA) is proposed and compared with two other evolutionary based algorithms, namely, particle swarm optimization (PSO) and genetic algorithm (GA), for diversity combining of signals travelling across the imperfect channels. The proposed algorithm adjusts the combiner weights of the received signal components in such a way that maximizes the SNR and minimizes the bit error rate (BER). The results indicate that the proposed method eliminates the need of channel estimation and can outperform the conventional diversity combining methods.
    Matched MeSH terms: Signal-To-Noise Ratio
  6. Yahaya Rashid AS, Ramli R, Mohamed Haris S, Alias A
    ScientificWorldJournal, 2014;2014:190214.
    PMID: 25101312 DOI: 10.1155/2014/190214
    The dynamic behavior of a body-in-white (BIW) structure has significant influence on the noise, vibration, and harshness (NVH) and crashworthiness of a car. Therefore, by improving the dynamic characteristics of BIW, problems and failures associated with resonance and fatigue can be prevented. The design objectives attempt to improve the existing torsion and bending modes by using structural optimization subjected to dynamic load without compromising other factors such as mass and stiffness of the structure. The natural frequency of the design was modified by identifying and reinforcing the structure at critical locations. These crucial points are first identified by topology optimization using mass and natural frequencies as the design variables. The individual components obtained from the analysis go through a size optimization step to find their target thickness of the structure. The thickness of affected regions of the components will be modified according to the analysis. The results of both optimization steps suggest several design modifications to achieve the target vibration specifications without compromising the stiffness of the structure. A method of combining both optimization approaches is proposed to improve the design modification process.
    Matched MeSH terms: Noise*
  7. Mohamed Moubark A, Ali SH
    ScientificWorldJournal, 2014;2014:107831.
    PMID: 25197687 DOI: 10.1155/2014/107831
    This paper presents a new practical QPSK receiver that uses digitized samples of incoming QPSK analog signal to determine the phase of the QPSK symbol. The proposed technique is more robust to phase noise and consumes up to 89.6% less power for signal detection in demodulation operation. On the contrary, the conventional QPSK demodulation process where it uses coherent detection technique requires the exact incoming signal frequency; thus, any variation in the frequency of the local oscillator or incoming signal will cause phase noise. A software simulation of the proposed design was successfully carried out using MATLAB Simulink software platform. In the conventional system, at least 10 dB signal to noise ratio (SNR) is required to achieve the bit error rate (BER) of 10(-6), whereas, in the proposed technique, the same BER value can be achieved with only 5 dB SNR. Since some of the power consuming elements such as voltage control oscillator (VCO), mixer, and low pass filter (LPF) are no longer needed, the proposed QPSK demodulator will consume almost 68.8% to 99.6% less operational power compared to conventional QPSK demodulator.
    Matched MeSH terms: Signal-To-Noise Ratio
  8. Ibrahim IA, Ting HN, Moghavvemi M
    J Int Adv Otol, 2019 Apr;15(1):87-93.
    PMID: 30924771 DOI: 10.5152/iao.2019.4553
    OBJECTIVES: This study uses a new approach for classifying the human ethnicity according to the auditory brain responses (electroencephalography [EEG] signals) with a high level of accuracy. Moreover, the study presents three different algorithms used to classify the human ethnicity using auditory brain responses. The algorithms were tested on Malays and Chinese as a case study.

    MATERIALS AND METHODS: The EEG signal was used as a brain response signal, which was evoked by two auditory stimuli (Tones and Consonant Vowels stimulus). The study was carried out on Malaysians (Malay and Chinese) with normal hearing and with hearing loss. A ranking process for the subjects' EEG data and the nonlinear features was used to obtain the maximum classification accuracy.

    RESULTS: The study formulated the classification of Normal Hearing Ethnicity Index and Sensorineural Hearing Loss Ethnicity Index. These indices classified the human ethnicity according to brain auditory responses by using numerical values of response signal features. Three classification algorithms were used to verify the human ethnicity. Support Vector Machine (SVM) classified the human ethnicity with an accuracy of 90% in the cases of normal hearing and sensorineural hearing loss (SNHL); the SVM classified with an accuracy of 84%.

    CONCLUSION: The classification indices categorized or separated the human ethnicity in both hearing cases of normal hearing and SNHL with high accuracy. The SVM classifier provided a good accuracy in the classification of the auditory brain responses. The proposed indices might constitute valuable tools for the classification of the brain responses according to the human ethnicity.

    Matched MeSH terms: Noise/adverse effects
  9. Ishak WS, Zhao F, Rajenderkumar D, Arif M
    Int Tinnitus J, 2013;18(1):35-44.
    PMID: 24995898 DOI: 10.5935/0946-5448.20130006
    The general consensus on the roles of hearing loss in triggering tinnitus seems not applicable in patients with normal hearing thresholds. The absence of hearing loss on the audiogram in this group of patients poses a serious challenge to the cochlear theories in explaining tinnitus generation in this group of patients.
    Matched MeSH terms: Noise*
  10. Nasir MH, Rampal KG
    Med J Malaysia, 2012 Feb;67(1):81-6.
    PMID: 22582554 MyJurnal
    Sensorineural hearing loss is a common and important source of disability among the workers and often caused by occupational noise exposure. Aims of the study were to determine the prevalence and contributing factors of hearing loss among airport workers. A cross-sectional study was carried out at an airport in Malaysia. This study used stratified sampling method that involved 358 workers who were working in 3 different units between November 2008 and March 2009. Data for this study were collected by using questionnaires eliciting sociodemographic, occupational exposure history (previous and present), life-style including smoking habits and health-related data. Otoscopic and pure-tone audiometric tests were conducted for hearing assessment. Noise exposure status was categorize by using a noise logging dosimeter to obtain 8-hour Time-Weighted Average (TWA). Data was analyzed by using SPSS version 12.0.1 and EpiInfo 6.04. The prevalence of hearing loss was 33.5%. Age >40 years old (aOR 4.3, 95%CI 2.2-8.3) is the main risk factors for hearing loss followed by duration of noise exposure >5 years (aOR 2.5, 95%CI 1.4-4.7), smoking (aOR 2.1, 95%CI 1.2-3.4), duration of service >5 years (aOR 2.1, 95%CI 1.1-3.9), exposure to explosion (aOR 6.1, 95%CI 1.3-29.8), exposure to vibration (aOR 2.2, 95%CI 1.1-4.3) and working in engineering unit (aOR 5.9, 95%CI 1.1-30.9). The prevalence rate ratio of hearing loss for nonsmokers aged 40 years old and younger, smokers aged 40 years old and younger, non-smokers older than 40 years old and smokers older than 40 years old was 1.0, 1.7, 2.8 and 4.6 respectively. This result contributes towards better understanding of risk factors for hearing loss, which is relatively common among Malaysian workers.
    Matched MeSH terms: Hearing Loss, Noise-Induced/etiology*; Hearing Loss, Noise-Induced/epidemiology
  11. Thomas N, Mariah AN, Fuad A, Kuljit S, Philip R
    Med J Malaysia, 2007 Jun;62(2):152-5.
    PMID: 18705450 MyJurnal
    Thirty-two points in Kuala Lumpur were selected where traffic personnel were on duty. Sound level readings were taken three times a day. Generally, the traffic noise levels were between 75 dBA to 85 dBA. The maximum sound level recorded was 108.2 dBA. Noise emitted by traffic equipment and vehicles were up to 133 dBA. Results of audiometric tests revealed that out of 30 who were tested, 24 or 80% were positive for noise-induced hearing loss. A questionnaire survey revealed a lack of knowledge on occupational safety and personal protective equipment.
    Matched MeSH terms: Hearing Loss, Noise-Induced/etiology*; Hearing Loss, Noise-Induced/prevention & control; Noise, Occupational/adverse effects*; Noise, Transportation/adverse effects*
  12. Maisarah SZ, Said H
    Med J Malaysia, 1993 Sep;48(3):280-5.
    PMID: 8183139
    A total of 524 industrial workers were studied. They consisted of 442 noise exposed and 82 non-noise exposed workers. The purpose was to compare the prevalence of sensori-neural hearing loss among the noise exposed and the non-noise exposed workers, to study their knowledge on the hazard of noise to hearing and the workers' attitude towards the hearing protection devices. The prevalence of sensori-neural hearing loss was significantly higher among the noise exposed workers, i.e., 83% versus 31.7% (p < 0.01). However, the prevalence of hearing impairment was much lower for both groups, being 30.1% for the noise exposed and 3.7% for the non-noise exposed group. Although hearing protection devices were provided to 80.5% of the workers, only 5.1% were wearing them regularly. The possibility of developing hearing loss due to exposure to excessive noise was only known by 35.5% of the noise exposed workers. This awareness was found to have a positive correlation with the workers' compliance to the hearing protection devices. Our findings highlight the need for workers to be educated on the hazards of excessive noise exposure to hearing.
    Matched MeSH terms: Hearing Loss, Noise-Induced/epidemiology*
  13. Chong FY, Jenstad LM
    Med J Malaysia, 2018 12;73(6):365-370.
    PMID: 30647205
    INTRODUCTION: Modulation-based noise reduction (MBNR) is one of the common noise reduction methods used in hearing aids. Gain reduction in high frequency bands may occur for some implementations of MBNR and fricatives might be susceptible to alteration, given the high frequency components in fricative noise. The main objective of this study is to quantify the acoustic effect of MBNR on /s, z/.

    METHODS: Speech-and-noise signals were presented to, and recorded from, six hearing aids mounted on a head and torso simulator. Test stimuli were nonsense words mixed with pink, cafeteria, or speech-modulated noise at 0 dB SNR. Fricatives /s, z/ were extracted from the recordings for analysis.

    RESULTS: Analysis of the noise confirmed that MBNR in all hearing aids was activated for the recordings. More than 1.0 dB of acoustic change occurred to /s, z/ when MBNR was turned on in four out of the six hearing aids in the pink and cafeteria noise conditions. The acoustics of /s, z/ by female talkers were affected more than male talkers. Significant relationships between amount of noise reduction and acoustic change of /s, z/ were found. Amount of noise reduction accounts for 42.8% and 16.8% of the variability in acoustic change for /s/ and /z/ respectively.

    CONCLUSION: Some clinically-available implementations of MBNR have measurable effects on the acoustics of fricatives. Possible implications for speech perception are discussed.

    Matched MeSH terms: Noise
  14. Manakandan SK, Rosnah I, Mohd Ridhuan J, Priya R
    Med J Malaysia, 2017 08;72(4):228-235.
    PMID: 28889134 MyJurnal
    BACKGROUND: The most crucial step in forming a set of survey questionnaire is deciding the appropriate items in a construct. Retaining irrelevant items and removing important items will certainly mislead the direction of a particular study. This article demonstrates Fuzzy Delphi method as one of the scientific analysis technique to consolidate consensus agreement within a panel of experts pertaining to each item's appropriateness. This method reduces the ambiguity, diversity, and discrepancy of the opinions among the experts hence enhances the quality of the selected items. The main purpose of this study was to obtain experts' consensus on the suitability of the preselected items on the questionnaire.

    METHODS: The panel consists of sixteen experts from the Occupational and Environmental Health Unit of Ministry of Health, Vector-borne Disease Control Unit of Ministry of Health and Occupational and Safety Health Unit of both public and private universities. A set of questionnaires related to noise and chemical exposure were compiled based on the literature search. There was a total of six constructs with 60 items in which three constructs for knowledge, attitude, and practice of noise exposure and three constructs for knowledge, attitude, and practice of chemical exposure. The validation process replicated recent Fuzzy Delphi method that using a concept of Triangular Fuzzy Numbers and Defuzzification process.

    RESULTS: A 100% response rate was obtained from all the sixteen experts with an average Likert scoring of four to five. Post FDM analysis, the first prerequisite was fulfilled with a threshold value (d) ≤ 0.2, hence all the six constructs were accepted. For the second prerequisite, three items (21%) from noise-attitude construct and four items (40%) from chemical-practice construct had expert consensus lesser than 75%, which giving rise to about 12% from the total items in the questionnaire. The third prerequisite was used to rank the items within the constructs by calculating the average fuzzy numbers. The seven items which did not fulfill the second prerequisite similarly had lower ranks during the analysis, therefore those items were discarded from the final draft.

    CONCLUSION: Post FDM analysis, the experts' consensus on the suitability of the pre-selected items on the questionnaire set were obtained, hence it is now ready for further construct validation process.

    Matched MeSH terms: Noise, Occupational/adverse effects
  15. Chandralekha G, Jeganathan R, Viswanathan, Charan JC
    Malays J Med Sci, 2005 Jan;12(1):51-6.
    PMID: 22605947
    Even though extensive studies have been conducted on the effect of noise exposure on hearing apparatus / auditory system, information on the effect of noise on the other body functions is sparse. The present study examined the effect of exposure of albino rats to acute and chronic noise stress on two important interlaced endocrine levels. In acute experiments the animals were exposed to 120 dB noise for a duration of 1, 2, 3 hrs. In chronic experiments the animals were exposed to noise for one hour daily for 30, 60 and 90 days. Plasma corticosterone and leptin levels were measured in these animals. There was significant elevation in the levels of corticosterone and leptin after exposure to noise stress. The elevation in corticosterone level after noise stress is in agreement with earlier reports. So noise acts like a stressor and elevates the secretion of the corticosterone, the stress hormone and leptin, the product of the ob gene there is an elevation in leptin levels after noise stress.
    Matched MeSH terms: Noise
  16. Habybabady RH, Mortazavi SB, Khavanin A, Mirzaei R, Arab MR, Mesbahzadeh B, et al.
    Malays J Med Sci, 2018 Sep;25(5):48-58.
    PMID: 30914862 DOI: 10.21315/mjms2018.25.5.5
    Background: Noise exposure causes loss of cochlea hair cells, leading to permanent sensorineural hearing loss, and initiates pathological changes to the bipolar primary auditory neurons (ANs). This study focuses on the effects of N-acetyl-l-cysteine (NAC) in protecting the density of spiral ganglion cells and in histological changes induced by continuous noise exposure in rats.

    Methods: Twenty-four male Wistar rats were randomly allocated into four experimental groups to receive NAC, saline, noise, or both noise and NAC. Noise exposure continued for ten days. Saline and NAC were injected daily during the noise exposure, and 2 days before and after the noise exposure. Evaluation of cochlear histopathology and the density of spiral ganglion cells was performed 21 days after exposure.

    Results: In the animals exposed to noise, a reduction in the density of spiral ganglion cells was evident in both the basal and middle turns of the cochlea. This improved on receiving NAC treatment (P = 0.046). In the histopathology evaluation, some histological changes, such as disorganised architecture of the outer hair and supporting cells and a slightly thickened basilar membrane, were found in the basal turns in the noise group.

    Conclusion: NAC offered partial protection against noise exposure by improving the density of spiral ganglion cells and reducing morphological changes.

    Matched MeSH terms: Noise
  17. Abd Hamid AI, Yusoff AN, Mukari SZ, Mohamad M
    Malays J Med Sci, 2011 Apr;18(2):3-15.
    PMID: 22135581 MyJurnal
    In spite of extensive research conducted to study how human brain works, little is known about a special function of the brain that stores and manipulates information-the working memory-and how noise influences this special ability. In this study, Functional magnetic resonance imaging (fMRI) was used to investigate brain responses to arithmetic problems solved in noisy and quiet backgrounds.
    Matched MeSH terms: Noise
  18. Swami CG, Ramanathan J, Charan Jeganath C
    Malays J Med Sci, 2007 Jul;14(2):28-35.
    PMID: 23515367 MyJurnal
    The noise stress, after it passes through the hearing apparatus, not only affects the auditory apparatus but also other body functions. The alterations in the levels of cortical hormone, adrenocorticosterone, nor-epinephrine hormone (which are primarily considered as stress hormones) on follicular stimulating hormone, testosterone, and lutinizing hormone were reported in relation with stress. Male albino rats weighing 200 to 250 grams were exposed to 100 dB of noise for one hour and three hours in acute group and daily one hour exposure for 60 day, and 90 day in chronic group. The serum testosterone levels were measured in these animals. There was significant reduction in serum testosterone levels and this was similar with earlier reports. The tissues were collected for light and confocal microscopic study. 100dB of traffic noise exposure of varying duration had definite permanent effect on testicular histology and morphology and on the male sex hormone. The adaptation mechanism was noticed at the hormonal level only but the structural changes noticed were definite and permanent. The agglutinated dead sperms revealed the possibility of infertily when chronically exposed to noise stress.
    Matched MeSH terms: Noise
  19. Rus RM, Daud A, Musa KI, Naing L
    Malays J Med Sci, 2008 Oct;15(4):28-34.
    PMID: 22589635
    The purpose of this study was to determine the sawmill workers' knowledge, attitude and practice (KAP) in relation to noise-induced hearing loss (NIHL). A cross-sectional study was conducted involving 83 workers from 3 factories in Kota Bharu, Kelantan. Questionnaires were distributed to obtain the socio-demography, knowledge, attitude and practice level in relation to noise-induced hearing loss (NIHL). The weak areas identified in the knowledge section were treatment aspects (15.5%), signs and symptoms of NIHL (20.2%) and risk factors (31%). As for attitude; the prevention aspects were the lowest (25.3%), followed by risk taking attitude (26.2%), and causes of hearing loss (42.1%). Overall, the practice was not encouraging at all. It is important to have an education program to raise workers' awareness and to improve their attitude and practices towards noise-induced hearing loss.
    Matched MeSH terms: Hearing Loss, Noise-Induced
  20. 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: Signal-To-Noise Ratio
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