Effect of age on inter and intra-subject variability in acceptable noise level (ANL) in listeners with normal hearing

Several industrial engineering and psychological studies have shown that noise affects the important aspects of communication for both adults and children. For speech understanding by hearing aids users and language development in children, an accurate hearing is very important. A metric has been developed for measuring an individualʹs acceptance of noise while listening to speech in quiet. This metric is known as Acceptable Noise Levels (ANLs). Studies have shown large inter-subject variability in acceptance of background noise. An argument has been made that an acceptance of background noise is a “means” that will help to solve the puzzle and monumental problem of hearing aid rejection. Meanwhile, within subject age dependency has not been investigated. This study is conducted to determine if ANL inter and intra-subject variability under music signal depends on age. Twenty subjects participated in the study (average age = 29; SD = 3.7; range 23-35 years). All participants had hearing level not worse than 25dB HL at octave frequencies from 250Hz to 4000Hz. Listeners’ task was to adjust the level of music played in quiet to their most comfortable listening level and then to adjust the level of background noise to the maximum level that they still consider acceptable while listening to music. Further, music is not a speech signal that many researchers have used to determine the significance of age on ANL inter-subject variability. Results of this study supported the findings of others on age dependency, which shows that ANL inter and intra-subject variability is independent of age.