Audiometry equipment shall be procured, in the form of test boxes, audiometry and headphones, as well as accompanying services, for the best possible implementation of hearing tests for adults in the Health Survey in Nord-Trøndelag (HUNT4). The procurement builds on the Norwegian Public Health Institute's defined area of responsibility. The quality of the data basis will be of decisive importance for the result and for knowledge on and understanding of the underlying reasons and thereby, the option to develop possible measures with benefits thereof, that can affect public health.