Reverting to the noise principle referred to in the last article it will be discovered that the worker finds the clang of hammer or the rat-tat of the riveting machine adversely affects production. Psychologically, it has been proved that the distraction due to noise lowers his output, because of the cross-currents of attention. Recently, a case was noted at Otahuhu shops. One of the workers in the undercarriage shop, where there is considerable noise due to the nature of the work, complained of feeling sick and applied for a change of shop. Investigation followed and, as a result the employee was transferred to another shop where there was, comparatively speaking, silence. Reports indicated in a definite manner that noise was a large factor in his output, while no further complaints as to his health have since been made.

On broad lines, too, noise is a fatigue factor which affects, to a serious degree, the output scheduled for the period. The schedules for jobs do not show this to any extent because of the method of computation, but a superficial examination of the employees leaving the engineering shops, as compared with those in the painting or upholstery sheds, indicates the truth of the laboratory findings. There is the strain produced by noise as well as that which is the outcome of work, irrespective of the amount of bodily exertion which the job demands. That this has a serious effect upon the nervous system cannot be denied for it reacts upon the worker who cannot make the correct motor response in a situation demanding accurate perception of the position.