If speech is the source of noise, how can the source be eliminated or reduced?

The exposure to noise can be reduced by eliminating the source of noise (if possible), substituting the source with a quieter one, applying engineering modifications, using administrative controls, and by using protective equipment. It is generally agreed that the solutions controlling the source are more cost effective than those controlling noise along the propagation path. Administrative controls and the use of personal protective equipment are measures that control the noise at the receiver and are supposed to be applied only if measures at the source are not possible. However, in this line of argumentation human beings are usually only treated as receivers of noise but not as noise sources. Results are reported in which an inverse Lombard effect or rather the Fletcher effect is used to reduce the speech effort and thus the speech level of persons. A feasibility study shows that the speech level can be lowered by up to 3 dB without the necessary manipulation being perceived to be distracting.