Efficacy of Digital Noise Reduction Strategies: A Hearing Aid Trial

The first goal of this project is to examine the efficacy of digital hearing aids incorporating three noise reduction strategies (i.e., directional microphones alone vs. directional microphones with DSP noise reduction algorithm 1 vs. directional microphones with DSP noise reduction algorithm 2) in terms of both speech understanding outcomes and functional outcomes. The second goal is to identify individual characteristics that are predictive of successful functional outcomes with hearing aids.

This study employs a multi-site, randomized, blinded, 2x2 factorial parallel group design. Three hundred subjects will be studied at three VA Medical Centers (Mountain Home, TN; Bay Pines, FL; and Los Angeles, CA) over a period of three years.

Objective (word recognition ability and performance with degraded speech stimuli) subjective (self-assessment questionnaires, personality and depression assessments) and cost-effectiveness assessments will be measured for 4 randomized treatment groups receiving different digital hearing aid technology. Subjects will be randomly assigned to wear hearing aids with directional microphones alone or directional microphones with noise reduction algorithm 1 or directional microphones with noise reduction algorithm 2 for a period of 8 weeks. Subjects will complete post-testing after 8 weeks of hearing aid use.

Inclusion criteria

• adult onset sensorineural hearing loss
• English as the first language
• bilateral symmetrical sensorineural hearing loss
• Patient is a candidate for directional microphone technology.
• average audiometric thresholds for 500, 1000, 2000, 3000, and 4000 Hz no better than 25-dB HL in either ear.
• no history of hearing aid use in the past 10 years
• appropriate cognitive skills to participate in the study as determined by a passing score on the Mini Mental Scale.
• Patient has a local telephone and address.

Exclusion criteria

• evidence of outer ear, middle ear, or retrocochlear pathology
• any threshold from 500 to 2000 Hz exceeds 70-dB HL
• known neurological or psychiatric disorders as determined by chart review
• known comorbid diseases that would prevent completion of the study as determined by chart review
• visual impairment that would interfere with reading the questionnaires