Loudness discomfort level and reliability as a function of instructional set.

Loudness discomfort levels (LDLs) for a 12-speaker babble were measured in 20 subjects with normal hearing sensitivity for two instructional sets, listening in the sound field. One instructional set asked the listener to indicate when they would choose 'not to listen for any period of time'. The second instructional set asked the listeners to indicate when they 'would choose not to listen for 15 minutes or longer'. A simple up-down adaptive procedure was used to measure LDLs. Data were gathered on both instructional sets for all listeners. LDLs for each instructional set were repeated on four separate occasions within a range of 1-3 weeks. The average LDLs for the instructions utilizing the criterion of choosing not to listen for any period of time were 9 dB higher than the criterion of choosing not to listen for 15 minutes or longer. The reliability of LDLs for both instructional sets was high, ranging from correlations of 0.90-0.97 for the criterion of choosing not to listen for any period of time, and ranging from correlations of 0.62-0.89 for the criterion of listening for 15 minutes or longer. The criterion of choosing not to listen for any period of time resulted in slightly more reliable measures. These results support the importance of considering the instructions given to a person to measure LDLs, and hence for where to set the saturation sound pressure level of a hearing aid. Also, with appropriate methods, LDLs can be reliably measured in the sound field.