Acceptable noise level test: bases and theories

Acceptable noise level (ANL) is the loudest level of background noise that human can tolerate while listening a running speech. ANL test is used for the prediction that whether a hearing aid (HA) candidate can use HA successfully by determining how well the individual tolerates background noise while listening to speech. In the current review, we reviewed the basis and theories of the ANL test and the factors that identified from the studies that have conducted on ANL and the influence of this test in increasing the quality of life of hearing aid users along with a discussion of its application in clinical audiology.
Research showed that subjects with a higher tolerance for background noise are most probable to be the successful hearing aid users. Clinical trials demonstrated that ANL test provides reliable results and can predict HA successful use with 85% accuracy.
Acceptable noise level is a reliable and valid test that can be used as a predictive index for the successful application of HA, and it is applicable in before/after HA fitting assessments. Thus, it is suggested that ANL can be implemented in the fitting and counseling process of HAs prescription. Further studies are required to resolve biases over the employment of this test in bilinguals.