ISO INTERNATIONAL STANDARD 9996 Firstedition 1996-12-15 Mechanical vibration and shock- Disturbance to human activity and performance Classification Vibrations et chocs mecaniques-Perturbation de I'activite et du travail desindividusClassification ISO Reference number ISO9996:1996(E) Copyright Intemational Organization for Standardization Not for Resale ISO9996:1996(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO committees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitteehasbeenestablishedhas liaison with IsO, also take part in the work. IsO collaborates closely with the International Electrotechnical Commission(lEC)onallmattersofelectrotechnicalstandardization. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. SubcommitteeSC 4, Human exposuretomechanicalvibrationand shock. Annex A of this International Standard is for information only ISO1996 or utilized in any form or by any means,electronic or mechanical, including photocopying and microfilm,withoutpermission inwritingfromthepublisher. International Organization for Standardization Case postale 56.CH-1211Geneve20.Switzerland Internet [email protected] X.400 C=ch; a=400net; p=iso; o=isocs; S=centra Printed in Switzerland ii Copyrightlntematinal Organization for Standardization Not for Resale ISO 9996:1996(E) @ ISO Introduction An important criterion for writing standard guidelines for the measurement and evaluation of human exposure to low-frequency oscillatory motion, mechanical vibration or shock is to prevent mechanical disruption and Vibrational forces and oscillatory motion can reduce the ease and efficiency of human sensorimotor and cognitive activity and task performance in two main ways. First, there can be direct (and usually instantaneous) mechanical induced by the motion or vibration stress. Unlike direct, mechanically induced disruption of activity, physiologically mediated effects may exhibit any or all of the following features: a) latency (i.e. the effect may take some time to become manifest following the onset of the stimulus); (g a threshold (minimum average mechanical stimulus level required to provoke the effect); C) environment);and d) persistenceforawhileaftertheprovocativestimulushas abated orceased. Relative motion or vibration of the perceived surroundings as well as of the person can also affect the physiological and cognitive state adversely (as indeed can illusory low-frequency motion), and hence jeopardize performance and safety. In many circumstances, more than one of these mechanisms of interference with human action may operate at the same time. When the criterion of evaluation of human exposure to low-frequency motion, mechanical vibration, or shock is the preservation of unimpaired activity, task performance, or safety, the relative weighting applied to standard guidelines for the evaluation of human exposure to vibration or shock expressed as functions of frequency, performed in the mechanical environment. ii Copyright International Organization for Standardizatior