Speech recognition abilities in noise for children with severe-to-profound unilateral hearing impairment

The purpose of this research was to compare the signal-to-noise ratio required for equal performance for children (aged 6-14 years) with normal hearing (N=17) versus those with severe-to-profound unilateral hearing impairment (N=20) who can be at a disadvantage, particularly when sounds are presented to the impaired ear. The listening environment is designed to approximate that which is encountered in a typical classroom.

All signals (Hearing in Noise Test-Children and Nonsense Syllable Test) were presented in the sound field from various azimuths with continuous noise presented from all quadrants. The children were required to repeat twenty items, from each test, in each listening condition. The intensity of the presentations was varied based on the accuracy of previous items. Average signal-to-noise ratios are compared between and within groups.

(1) In most listening conditions, significantly greater signal-to-noise ratios were needed by those with unilateral hearing impairment than those with normal hearing, on both speech tests. (2) In every listening condition, both groups required significantly greater signal-to-noise ratios to perform equally well on the Nonsense Syllable Test as on the Hearing-In-Noise Test-Children. (3) For the Hearing-In-Noise Test-Children, children with normal hearing required significantly greater signal-to-noise ratios when facing the signal than when the signal was presented to a normally hearing ear (monaural direct). (4) On both tests, the children with unilateral hearing impairment required significantly greater signal-to-noise ratios when facing the signal than in the monaural direct condition. (5) On both tests, the children with unilateral hearing impairment required significantly greater signal-to-noise ratios when the signal was presented to the impaired ear (monaural indirect) than when facing the signal.

(1) The children with unilateral hearing impairment require a more advantageous listening condition to perform equally as well as their normally hearing counterparts. (2) All of the children benefited from signals delivered in a monaural direct condition. (3) The children with unilateral hearing impairment performed best in the monaural direct condition or when facing the signal at zero degrees. (4) Significantly greater signal-to-noise ratios were needed for both groups when restricted contextual cues were available versus when sentential cues were available.