Short and long compression release times: speech understanding, real-world preferences, and association with cognitive ability.

BACKGROUND

Several previous investigations have explored the relationship between cognitive abilities and speech understanding with short and long hearing aid compression release times in adult hearing aid wearers. Although there was consensus that such a relationship exists, the details have not been consistent across studies. This investigation was designed to further explore, extend, and generalize this topic.

PURPOSE

Questions addressed: (1) the association between cognitive abilities and speech understanding with short and long release times for more ecologically valid speech than in previous studies, (2) the presence or absence of release time preferences in daily life, and (3) the association between the laboratory measures and real-world release time preferences.

RESEARCH DESIGN

The study was a blinded randomized crossover trial.

STUDY SAMPLE

Twenty-four subjects with mean age of 72yr completed the study. They were experienced users of bilateral amplification with mild to moderately-severe symmetrical hearing losses. They were healthy, English-speaking active seniors recruited using advertisements and letters.

DATA COLLECTION AND ANALYSIS

There were five test sessions. They included audiometric and cognitive testing, fitting bilateral Oticon Adapto hearing aids, a four-week trial with either short or long release time, outcome measures, a four-week trial with the other release time, further outcome measures, and a final interview.

RESULTS

Taken together with the previous studies, the results suggest that compression processing release time is more critical for patients with lower cognitive abilities than for those with higher cognitive abilities. Further, we postulate that the best release time for listeners with lower cognitive abilities depends on the redundancy of the tested speech. Those with lower cognitive abilities might benefit from short release time when contextual speech is used, or when speech is rich in context, release time might not be important; however, when speech is low in semantic context, listeners with lower cognitive abilities might require long release time for best performance. Listeners do appear to be able to distinguish between long and short release time processing in daily life listening. However, release time preference was not predictable from cognitive abilities or aided measures of speech understanding. About two-thirds preferred long release time, and one-third preferred short release time.

CONCLUSION

The relationship between cognitive abilities and performance with short and long release time processing was supported and further elucidated in this research. In addition, release time was seen to be a salient variable in subjective performance with amplification in daily life. Accurate prospective prescription of release time has the potential to make a material contribution to successful amplification provision.