The lumping mass effect on frequencies of beam-columns

The results of two experiments are reported in which 55 university staff and students carried out a variety of mental tasks and were required to adjust their ambient noise to a “comfortable working level”. Preferred listening levels whilst carrying out mental tasks in noise show very large between-subject differences. Some subjects prefer to work in the quiet and others in “deafening” noise levels (over 90 dB(A)) and yet the latter suffer no deterioration in task performance compared with the former. Preferred listening levels are determined in part by (1) the type of noise, (2) the degree of task difficulty and (3) the personality traits of extroversion and psychoticism, and possibly by noise sensitivity. Such personal differences as sex, age and “status” of the subject do not apparently affect preferred listening levels. These levels are shown to be those at which subjects judge a noise over which they have no control to be between “quiet” and “noticeable”.