A matching technique, similar in principle to that employed by Ashley (1970) has been adopted, to evaluate equal sensation levels between sinusoidal and wide-band random vibrations. The technique employed improved methodology, better facilities, and all the three translational modes. A series of two experiments were conducted. In experiment 1, subjects were exposed to four levels of sinusoidal vibrations, corresponding to ISO's (1974) fdp 16 min, 25 min, 1 h and 2.5 h boundaries at 6 hz in the vertical mode, and at 2 hz in the back-to-chest and right-to-left side modes. Subjects were asked to rate their vibration sensations on a ten point scale and to categorise their sensations on a four point category scale, while taking into account the fdp durations. They were then asked to match the random vibration to sinusoidal vibration for an equal sensation effect if exposed over such durations. In experiment 2, the four matched random vibration levels were employed as reference levels. Subjects were then asked to match various sinusoidal vibrations (1-20 hz) to random vibrations to achieve equal sensations, again taking into consideration the stipulated fdp durations. The data gathered from both experiments were analysed and the results (mean) of experiment 1, in general, showed that at higher fdp levels, random vibrations when weighted with appropriate iso weighting networks gave significantly lower rms acceleration values than sinusoidal vibration levels. Results (mean) of experiment 2 yielded equal sensation contours whose shapes revealed some difference both at low and high frequency ends, compared with iso boundary profiles. Changes in contour profiles with acceleration levels were also observed. Significant differences between sinusoidal and random vibrations in all the three vibration modes were observed. The paper also discusses some problems encountered by some subjects during the course of the investigation. /Author/TRRL/

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  • Corporate Authors:

    Taylor & Francis

    4 Park Square, Milton Park
    Abingdon,   United Kingdom  OX14 4RN
  • Authors:
    • Rao, BKN
    • Jones, B
  • Publication Date: 1978-2

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  • Accession Number: 00182764
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Oct 31 1978 12:00AM