The acceptable noise level: The effect of repeated measurements

Abstract

Objective: This study explores if increasing number of repetitions might improve the precision of the acceptable noise level (ANL) test. Design: We measured twelve ANL repetitions, i.e. four complete ANL tests (4 × 3 repetitions), at one session using diotic presentation and a non-semantic ANL version. Study sample: Thirty-two normal-hearing adults. Results: Small order and fatigue effects were seen. We used the coefficient of repeatability (CR) to assess the repeatability; CRs ranged between 3.9 and 7.6 dB for the four ANL tests. Using the twelve ANL repetitions we removed the variability of the ANL across subjects by normalizing the data to the individual mean ANL for the twelve repetitions. The mean normalized ANL across the subjects rapidly approached the ANL normalized to the individual mean for the 12 repetitions (0 dB), and after three repetitions the SD seemed to be stable at about 3 dB. Conclusions: The findings suggest that both order and fatigue affect the ANL. The findings also suggest that it may be more accurate to speak of an acceptable noise range than ANL. These findings have large implications for how we understand acceptable noise and it would explain a large part of the variability seen among normal-hearing and perhaps hearing-impaired subjects.

Key Words::

• Acceptable noise level
• repeated measures
• training
• fatigue
• order effect
• background noise level
• most comfortable level
• coefficient of repeatability

Acknowledgements

Parts of the results in this article were previously published in Swedish (2012) as a Master thesis in Audiology at Lund University by the second and third author.

Declaration of interest: No outside funding or grants in support of this work were received. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.