However, these studies have been mostly carried out among adult users and there are relatively limited results in children 12 - 14 due to difficulties in testing young children under challenging listening conditions and obtaining robust outcomes: e.g. This has been termed as "bimodal benefit" 8.īimodal benefit in CI recipients has recently received much attention, and previous studies have shown its significant positive effect on speech recognition in noise and on functional performance in daily life as well as on the improvement of localisation and music perception skills 3 9 - 11. Hence, contralateral HA use offers an alternative to bilateral cochlear implantation in that unilateral CI recipients benefit from the LF cues provided through acoustic signals from contralateral HA in addition to electrical signals from the CI. Therefore, an increasing number of CI recipients wear a hearing aid (HA) to make use of LF residual hearing on the contralateral side. On the other hand, cochlear implantation is still performed unilaterally in several countries due to economic reasons. Over the past years, the trend in cochlear implantation has been the extension of indications to severe as opposed to uniquely profound hearing losses. Current CI technology offers good opportunities for formal and informal language acquisition in deaf children 4 5 as well as good speech understanding in quiet environments in postlingually deafened adults 6, but it still remains insufficient to provide fine acoustic information especially in the low frequency (LF) domain that may contribute to better speech perception in noise 7. One main advantage of binaural hearing is the improvement in speech perception in the presence of noise, which is a common downfall with cochlear implant (CI) recipients. Research in normal hearing subjects indicated a 3 dB improvement in BSE for the binaural speech recognition threshold and an average increase of 3 dB SNR for HSE which is more dominant for attenuation of high frequencies and can cause even 8 to 10 dB of improvement 3. On the other hand, HSE results from the physical placement of the head which acts as an acoustic barrier and leads to an increase in SNR in the ear far from the noise when signal and noise are spatially separate. BSE refers to the capacity of the central auditory system to process the stimuli received from each ear and to reproduce it with a higher signal-to-noise ratio (SNR) by comparing interaural time and intensity differences. Two basic effects that involve advantages for binaural hearing are binaural squelch effect (BSE) and head shadow effect (HSE). It is well known that binaural hearing provides important benefits over monaural hearing, especially under challenging listening conditions 1 2. In conclusione, la maggioranza dei bambini con CI hanno mostrato BSE ed HSE con un miglioramento significativo nella percezione vocale in presenza di rumore. L'analisi statistica condotta ha evidenziato una differenza significativa sia nel confronto tra le tre condizioni di ascolto che per l'analisi post-hoc (p < 0.001). I valori medi di BSE e di HSE osservati sono 11.8% e 17.1% rispettivamente. Il test è stato eseguito in tre condizioni di ascolto: (1) ascolto bimodale con sorgente di rumore sul lato HA (2) ascolto con CI con sorgente di rumore sul lato HA (3) ascolto con CI con sorgente di rumore sul lato CI. Per valutare la performance vocale in presenza di rumore è stato utilizzato un test di identificazione vocalica. Sono stati arruolati 19 bambini con CI che indossavano regolarmente una HA. Lo scopo di questo studio è stato quello di indagare il grado di effetto squelch binaurale (BSE) e di effetto ombra (HSE) nei bambini che fanno uso di impianto cocleare (CI) e protesi acustica controlaterale (HA).
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