Effectiveness of Hearing-aid Based Wind-noise Algorithm
Condition: Hearing Impairment
MeSH terms: Hearing Loss; Deafness
Study type: Observational

Summary: 
      Wind-noise is highly disturbing to hearing impaired individuals wearing hearing aids who wish
      to participate in outdoor conversations where wind is present or during activities such as
      walking or running. In these situations, wind noise significantly reduces signal-to-noise
      ratio and, consequently, the intelligibility of speech and sounds may be significantly
      impaired. This negative effect is exacerbated with the use of directional microphone schemes
      in the hearing iads. The objective of this project is to determine the efficacy of the MH
      Acoustics' multi-microphone wind-noise reduction invention for the digital hearing aids
      market. MH Acoustics' wind noise reduction technology is unique since it provides
      instantaneous convergence while maintaining directionality of the microphone array. Current
      commercial technologies do not provide this feature. We are hypothesizing that, due to the
      design of the algorithm, speech perception ability and sound quality perception will be
      better than that available with traditional directional and/or omnidirectional microphone
      schemes in windy environments.
    

Detailed description: 
      Two groups of subjects will be recruited to participate: Normal hearing adults and adults
      with mild to moderately severe hearing loss, ages 18-65. Pure tone audiometrics (re ANSI,
      1996) will be done to ascertain the hearing sensitivity through 6ooo Hz. Normal hearing will
      be defined as thresholds at or better than 20 dB HL (re ANSI, 1996). The only exclusion
      criterion for the group exhibiting hearing loss is that no thresholds up to and including
      3000 Hz will exceed 75 dB, so as to minimize the inclusion of subjects with "dead regions" in
      the cochlea.

      Subjects will be seen for four visits to the laboratory. The first visit will involve
      documentation of informed consent, and measurement of hearing thresholds. The second, third
      and fourth visits will consist of testing with the following measures (in random order for
      each subject) to determine if the various implementations of the wind noise reduction
      algorithm 1) impact speech perception ability, and/or 2) impact sound quality perception.
      Each session will take approximately 1.5 hours, with a maximum of six hours over all the
      sessions. The two speech perception tests that will be utilized include : 1) Connected Speech
      Test and Hearing in Noise Test, 2) The Hearing in Noise Test (HINT) (Nilsson, Soli, &
      Sullivan, 1994; Koch, Nilsson & Soli, 1995. Overall Impression of Sound Quality and Ratings
      of Annoyance will be used as subjective, or self-reported, measures of preference. Overall
      Impression will be influenced by the audibility and masking effect of the noise bursts,
      whereas Annoyance ratings are significantly correlated to the high frequency emphasis of the
      stimulus, a potential impact of the extreme suppression conditions (e.g., -18 dB) (Warner &
      Bentler, 2002; Miedema & Vos, 2003). Both measures will be analyzed as a function of the
      different time constants, gain reduction levels, and level of presentation.
    

Observational model: Case-Crossover
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Two groups (30 each) of subjects will be recruited to participate: Normal hearing adults
        and adults with mild to moderately severe hearing loss, ages 18-65. Pure tone audiometrics
        (re ANSI, 1996) will be done to ascertain the hearing sensitivity through 6ooo Hz. Normal
        hearing will be defined as thresholds at or better than 20 dB HL (re ANSI, 1996). The only
        exclusion criterion for the group exhibiting hearing loss is that no thresholds up to and
        including 3000 Hz will exceed 75 dB, so as to minimize the inclusion of subjects with "dead
        regions" in the cochlea.
      
Keywords: hearing aid algorithm; wind-noise suppression