On the basis of a number of surveys in commercial offices, criteria for tolerable office background noise levels are proposed. Questions were asked of people working in these offices regarding their ability to telephone, to confer and to perform their work under the existing noise conditions. The speech interference levels of the background noises were determined in each case. The results are presented in a chart, which rates the noise conditions as a function of speech interference levels in each of three general types of offices, (a) executive offices, (b) general clerical offices, and (c) business machines offices.