PC-Based Rehabilitation of Auditory Function
Condition: Hearing Loss, Sensorineural
MeSH terms: Hearing Loss; Deafness; Hearing Loss, Sensorineural
Study type: Interventional

Summary: 
      Many older subjects experience difficulty in understanding speech in noisy environments. Part
      of this problem is related to changes that occur in the ear with age and compromise the
      hearing of high-pitched sounds. Another part of the problem with speech understanding relates
      to changes with age in the neural circuits of the brain that process different speech sounds.
      Evidence suggests that these changes in neural circuits are particularly large if hearing
      loss is present. Thus, while hearing aids may help compensate for hearing deficits by
      amplifying speech sounds, additional treatment is necessary to restore optimal neural
      connections in the brain so that speech sounds can be accurately distinguished from each
      other. We are developing PC-based training programs in an attempt to restore optimal neural
      connections. The current randomized trial will evaluate whether two months of training to
      improve the ability to discriminate different consonant sounds in noise will also improve the
      understanding of continuous speech and enhance auditory memory and other high-level auditory
      functions.
    

Detailed description: 
      More than 300,000 veterans with sensorineural hearing loss (SNHL) are fitted with VA-issued
      hearing aids (HAs) each year with the primary goal of improving their understanding of
      speech. Even older veterans without hearing loss experience a gradual decline in speech
      discrimination due to age-related changes in auditory function that compromise speech
      understanding in everyday environments. Neuroplastic reorganization within the central
      auditory system due to SNHL and aging contribute to these effects and compromise subjects'
      ability to process phonetic cues that are essential for understanding speech in noise. As a
      consequence, even when a HA restores high frequency signals to the cochlea in a patient with
      SNHL, speech understanding will remain suboptimal in the absence of rehabilitative perceptual
      learning.

      We have developed perceptual learning paradigms that drive this rehabilitative reorganization
      and significantly improve speech discrimination in new HA users. We now propose to test
      improved training paradigms in new and experienced HA users and older subjects with normal
      hearing. In Exp. 1 we will evaluate baseline speech discrimination in these populations using
      speech-reception thresholds (SRTs) in sentences, consonant-vowel-consonant nonsense syllable
      tests (CVC-NST), tests of tone-pattern discrimination, and tests of auditory short-term
      verbal memory (ASTVM). An analysis of the correlations of these measures will provide
      information about basic processes underlying impaired word and sentence identification. In
      Exp. 2 we will investigate the effects of CVC-identification training using
      performance-adapted masking noise. Based on our previous results, we anticipate that training
      will significantly improve CVC-NST scores. We will examine the extent to which training
      improves SRTs, tone-pattern processing, and ASTVM. In Exp. 3 we will train subjects in a
      tone-pattern identification task to evaluate the extent to which non-phonetic factors (e.g.,
      familiarity with the computerized hearing tests, placebo effects of training, improvements in
      auditory attention, etc.) may contribute to training benefit. In Exp. 4 we will compare the
      benefits of training with single-consonant syllables with the benefits of two-consonant
      syllable training studied in Exp. 2. Finally, in Exp. 5 we will study the benefits of CVC
      training using consonant-specific noise levels adjusted to compensate for intrinsic
      differences in the discriminability of different consonants and compare them to the benefits
      of global adaptive training from Exp. 2. The experiments will clarify fundamental mechanisms
      underlying deficits in speech discrimination and ASTVM, provide insight into the nature of
      training-related improvements, and elucidate the parameters needed to optimize hearing
      rehabilitation.

      Relevance to the VA patient care mission: HAs are relatively ineffective in improving the
      ability of hearing-impaired subjects to understand speech in many everyday listening
      situations. These experiments will clarify the extent to which perceptual training can
      improve speech discrimination and enhance ASTVM in these conditions in new and experienced HA
      users and older subjects with normal hearing. Perceptual training could potentially benefit
      millions of veterans who wear HAs as well as older veterans with normal hearing who
      experience difficulties in understanding and remembering speech.
    

Intervention name(s): Consonant Identification Training
Intervention type(s): Behavioral
Intervention description(s): Subjects received psychophysically adaptive, consonant identification training in consonant discrimination on PCs in their homes.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Auditory Perception; Hearing Loss; Presbycusis; Perceptual Learning; Hearing Prosthesis; Speech Discrimination; Delayed Treatment