Park, Mun Hum

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Park, Mun Hum
Alternative Name
Park, Munhum
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Email
munhum.pa@kmitl.ac.th

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    Item type:Publication,
    Analysis of warning sounds used in public transportation systems
    (2017-01-01)
    Chuprasert, Pavarit
    ;
    Phupantachsee, Nawasch
    ;
    Park, Munhum
    For the safety of passengers, warning sounds are used in public transportation services, for example, when the train doors are closed. Although the audibility of these sounds is normally required and must be regulated by transportation authorities, the associated noise levels are often unnecessarily high, which frequently lead to the passengers’ discomfort and complaints. In this study, we investigated the door-closing sounds used in the Bangkok Mass Transit System (BTS) Skytrain by evaluating the noise levels and spectral characteristics. The maximum A-weighted sound pressure level (L<inf>AFmax</inf>) was repeatedly measured at 7 representative positions within each car for two types of train, which differed in terms of the location of loudspeakers. The range of L<inf>AFmax</inf> was found to be 67.4 dBA to 97.2 dBA with the median at 77.1 dBA, and the train type was found to significantly influence the noise level (p=0.006), and so was the location in train car (p<0.001). The spectral analysis revealed that the door-closing warning sounds consisted of strong ~3-kHz tone bursts (with a few harmonics), which were found to be 15~20 dBA above the ambient level. The outcome of the study suggests that the warning sounds used in the BTS Skytrain are likely to distress the passengers due to the excessive playback level and the tonality. Further discussions are made on methods to reduce the psychological impact of the warning sounds on passengers while maintaining a good audibility.
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    Item type:Publication,
    The effect of "Twinkle Twinkle Little Star" on short-term memory
    (2018-01-01)
    Park, Munhum
    ;
    Chuprasert, Pavarit
    ;
    Kloemwilai, Achcharaphan
    ;
    Fahkrajang, Napat
    ;
    Sawetratanastien, Pruch
    Irrelevant speech effect (ISE) refers to the decrease in cognitive performance under the influence of a sound which is not related to the task. Typically, ISE has been quantified for speech noise by the rate of errors in recalling visually presented items (serial-recall task). Despite the limited effect size, non-speech sounds have also been shown to disrupt the short-term memory in serial-recall task, of which the spectro-temporal characteristics may easily be adjusted to investigate some aspects of ISE. In the current study, a well-known tune ‘Twinkle Twinkle Little Star’ was used to create a set of stimuli that differed in three factors: 1) Instrument type (played either on a MIDI piano or in pure tones); 2) number of notes per second (two or four); 3) playing order (original, reverse or random). The results showed some trends that the piano sound disrupts the task slightly more than the pure tone, and so does the four-note version than the two-note. When played in a random order, the error rate was higher than the original-/reverse-order versions, whereas the latter two conditions were almost equal. These trends may be explained in relation to the temporal and spectral variations between sound tokens.