Substitution Patterns of Phoneme Errors in Hearing Aid and Cochlear Implant Users

BACKGROUND AND OBJECTIVES: It is acknowledged that speech perceptual errors are increased in listeners who have sensorineural hearing loss as noise increases. However, there is a lack of detailed information for their error pattern. The purpose of the present study was to analyze substitution patterns of phoneme errors in Korean hearing aid (HA) and cochlear implant (CI) users who are postlingually deafened adults. SUBJECTS AND METHODS: In quiet and under two noise conditions, the phoneme errors of twenty HA and fourteen CI users were measured by using monosyllabic words, and a substitution pattern was analyzed in terms of manner of articulation. RESULTS: The results showed that both groups had a high percentage of nasal and plosive substitutions regardless of background conditions. CONCLUSIONS: This finding will provide vital information for understanding the speech perception of hearing-impaired listeners and for improving their ability to communicate when applied to auditory training.

Error Patterns Analysis of Hearing Aid and Cochlear Implant Users as a Function of Noise

BACKGROUND AND OBJECTIVES: Not all impaired listeners may have the same speech perception ability although they will have similar pure-tone threshold and configuration. For this reason, the present study analyzes error patterns in the hearing-impaired compared to normal hearing (NH) listeners as a function of signal-to-noise ratio (SNR). SUBJECTS AND METHODS: Forty-four adults participated: 10 listeners with NH, 20 hearing aids (HA) users and 14 cochlear implants (CI) users. The Korean standardized monosyllables were presented as the stimuli in quiet and three different SNRs. Total error patterns were classified into types of substitution, omission, addition, fail, and no response, using stacked bar plots. RESULTS: Total error percent for the three groups significantly increased as the SNRs decreased. For error pattern analysis, the NH group showed substitution errors dominantly regardless of the SNRs compared to the other groups. Both the HA and CI groups had substitution errors that declined, while no response errors appeared as the SNRs increased. The CI group was characterized by lower substitution and higher fail errors than did the HA group. Substitutions of initial and final phonemes in the HA and CI groups were limited by place of articulation errors. However, the HA group had missed consonant place cues, such as formant transitions and stop consonant bursts, whereas the CI group usually had limited confusions of nasal consonants with low frequency characteristics. Interestingly, all three groups showed /k/ addition in the final phoneme, a trend that magnified as noise increased. CONCLUSIONS: The HA and CI groups had their unique error patterns even though the aided thresholds of the two groups were similar. We expect that the results of this study will focus on high error patterns in auditory training of hearing-impaired listeners, resulting in reducing those errors and improving their speech perception ability.

Speech Perception in Older Listeners with Normal Hearing:Conditions of Time Alteration, Selective Word Stress, and Length of Sentences

BACKGROUND AND OBJECTIVES: Deficits of the aging auditory system negatively affect older listeners in terms of speech communication, resulting in limitations to their social lives. To improve their perceptual skills, the goal of this study was to investigate the effects of time alteration, selective word stress, and varying sentence lengths on the speech perception of older listeners. SUBJECTS AND METHODS: Seventeen older people with normal hearing were tested for seven conditions of different time-altered sentences (i.e., +/-60%, +/-40%, +/-20%, 0%), two conditions of selective word stress (i.e., no-stress and stress), and three different lengths of sentences (i.e., short, medium, and long) at the most comfortable level for individuals in quiet circumstances. RESULTS: As time compression increased, sentence perception scores decreased statistically. Compared to a natural (or no stress) condition, the selectively stressed words significantly improved the perceptual scores of these older listeners. Long sentences yielded the worst scores under all time-altered conditions. Interestingly, there was a noticeable positive effect for the selective word stress at the 20% time compression. CONCLUSIONS: This pattern of results suggests that a combination of time compression and selective word stress is more effective for understanding speech in older listeners than using the time-expanded condition only.