Int. Adv. Otol. 2009; 6(1); 74-82

Enhancement of speech intelligibility in digital hearing aids using directional microphone/ noise reduction algorithm
Somia Tawfik, Iman M. Sadek El Danasoury,  Hoda AbuMoussa,  Mai Fathy Naguib,  Fouad Naguib
Audiology Unit E.N.T. Department Faculty of Medicine, Ain shams university. maifnaguib@hotmail.com

Objective: We aims to detect the efficacy of directional microphone when combined with noise reduction algorithm in improving
speech intelligibility in noisy environments for hearing impaired subjects.

Materials and Methods: Twenty adult subjects with bilateral symmetrical sensory neural hearing loss of moderate to
moderately severe degree were examined. Aided assessment was done in two settings using BTE digital hearing aid. First
setting included: evaluation using noise reduction algorithm alone. Evaluation in the second setting was done using both noise
reduction algorithm and directional microphone. Aided evaluation consisted of speech discrimination scores in quiet and speech
in noise test in different noise scenarios. Just follow conversation test was done to detect the least signal to noise ratio a subject
can tolerate in each of the two settings. The subjective impression of the patient was assessed by a modified questionnaire for
hearing aid assessment.

Results: Investigation showed statistically significant improvement of aided speech discrimination scores in noise in the second
aided setting when speech was at zero degree azimuths and noise was at zero and 180 degrees azimuth.

Conclusion: Directional microphone when combined with noise reduction algorithm in a digital hearing aid, adds benefit in
improving speech intelligibility for patients with moderately-severe sensory neural hearing loss whatever the duration of the
hearing loss.