Working Memory Changes With Aging and Hearing Loss
Condition: Aging; Hearing Loss
MeSH terms: Hearing Loss; Deafness
Study type: Observational

Summary: 
      Hearing loss is one of the most common health concerns affecting 1 in 3 Americans over 60
      years of age rising to 1 in 2 for those over 85 years old. Contributions to hearing abilities
      provided by cognitive and memory processes are universally recognized as essential to
      adequate speech communication, but these processes are not well understood. Cognitive
      limitations in the ability to rapidly process sequential sounds occur with all listeners but
      may have more impact on older Veterans with and without hearing impairment. The purpose of
      this study is to examine and more thoroughly characterize the change in auditory working
      memory with hearing loss and increasing age. Young and older listeners with and without
      hearing loss will listen and report on two target sounds embedded in a stream of rapidly
      occurring sound. The investigators expect that older listeners without hearing loss will have
      more difficulty than young listeners but that older listeners with hearing impairment will
      have the most difficulty with this task even when the sounds they are listening to are
      adjusted to compensate for their hearing loss.
    

Detailed description: 
      The purpose of this pilot study is to understand how memory changes with aging and if
      failures of working memory during rapid sound processing may account for some of the speech
      perception difficulties reported by older Veteran listeners especially those with hearing
      loss. A period of processing interference (and limitation) has been identified during rapid
      auditory or visual processing. Specifically, when subjects are asked to report on two
      targeted events embedded in a rapid stream of distractor events, the ability to report on the
      second target is diminished when it occurs at an interval of approximately 200-400ms
      following the first target. This has been identified as a failure of working memory
      consolidation and is robust during both visual and auditory processing. Much is known about
      how the failure of working memory affects young normal hearing listeners but little is known
      of its effect on older listeners or listeners with hearing loss. A lengthened period of
      processing interference is very likely to be present among older listeners. This is important
      because speech is rapid and older listeners often report difficulty in auditory environments
      in which multiple speakers are present. Further, older listeners, who are more likely to have
      hearing loss, continue to report more problems hearing in noisy environments even with their
      hearing aids optimally functional. The presence of a prolonged period of processing
      interference in the auditory system could account for some of these complaints and, if more
      completely understood, could be remediated.

      Up to 75 subjects, ages 18-30 and 60-75 years will be invited to participate. Subjects will
      undergo a complete audiological evaluation done to assign them into one of three arms/groups
      of up to15 subjects each. Arms will be composed of young subjects with normal hearing (YNH),
      older subjects with normal hearing (ONH) and older subjects with mild hearing impairment
      (OHI). Each subject will be asked to listen to between 18 and 26 non-overlapping tones each
      30ms in duration followed by a 70ms silent interval. Target tones and tone complexes (T1 and
      T2) will be embedded in this stream. Sequences could contain (in equal probability) a) no
      target, b) T1 only, c) T2 only or d) both targets. At the end of each stream, the subject
      will be required to make an untimed judgment about whether the stream contained T1 (yes/no)
      and T2 (yes/no). This project is self-paced. The hypothesized findings are that young
      listeners without hearing impairment will have more difficulty reporting on T2 when it
      follows T1 by approximately 200-400ms than at any other interval. However, older listeners
      without hearing impairment will demonstrate a more prolonged period of interference (>400ms)
      with slightly poorer performance overall while older listeners with hearing impairment will
      have an even longer lasting period of processing interference and overall larger deficit
      (poorer performance) suggesting that increasing age and hearing impairment combine to reveal
      significant processing deficits for this group. These results would provide a much needed
      explanation of the ways in which rapid processing (precisely what speech is) is degraded by
      hearing impairment, aging, and a combination of the two.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        All populations meeting the inclusion criteria
      
Keywords: hearing loss; aging; short term memory; attentional blink