Search

Purpose: Speech recognition in noise is a ubiquitous problem in older listeners. Speech, the most commonly encountered noise in the real world, causes greater masking than noise maskers, a phenomenon called informational masking (IM). This is due to the lexical-semantic and/or acoustic-phonetic information present in speech maskers. In this study, we aimed to observe the age-related differences in speech recognition and the magnitudes of IM when the maskers varied in the type of linguistic information. Method: In 30 young and 30 older individuals, we measured the signal-to-noise ratio required to obtain 50% correct identification under four-talker babble (lexicalsemantic and acoustic-phonetic information), four-talker reverse babble (predominantly acoustic-phonetic information), and speech-shaped noise (SSN; energetic). Results: In both groups, the four-talker babble caused the greatest masking effect (worst performances), whereas the SSN resulted in the least masking effect (best performances). The effectiveness of IM due to the lexical-semantic information was comparable between the two groups. However, the effectiveness of IM due to the acoustic-phonetic information was significantly higher in the older listeners, causing worse performances. Conclusions: The greater effectiveness of IM due to the acoustic-phonetic information (worse performance) could be due to the minimal-to-mild highfrequency hearing loss and the consequent temporal processing deficits observed in the older listeners. However, it is possible that the older listeners can employ compensatory mechanisms (such as life experiences, contextual cues, employing higher listening efforts, among many possible other mechanisms) to overcome some of these deficits. [ABSTRACT FROM AUTHOR]

Purpose: This study investigates the acoustic environment of children with cochlear implants (CIs) and the relationship between exposure to speech, in noise and in quiet, and the children's lexical production up to 1 year after CI activation, while controlling for the effect of early individual differences in receptive vocabulary growth. Method: Eighteen children with CIs were observed at 3, 6, and 12 months after CI activation. Children's spontaneous word production during interaction with their mothers (types and tokens) and their expressive and receptive vocabulary size were considered. The characteristics of the acoustic environments in terms of acoustic scenes (speech in noise or in quiet, quiet, noise, music, and other) and of loudness ranges were assessed using data logging of the children's devices. Results: Data analysis showed that both the number of tokens and the number of types produced 1 year after CI activation were affected by the children'sexposure to speech in quiet with a loudness range between 40 and 69 dB. Expressive vocabulary size and types were affected by the receptive vocabulary knowledge that the children achieved over the first 3 months after CI activation. Conclusions: Our data support the role of speech environment and individual differences in early comprehension on lexical production. The importance of exposure to speech with particular characteristics for the lexical development of children with CIs and the implications for clinical practice are discussed. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to investigate whether bilateral cochlear implant (CI) listeners who are fitted with clinical processors are able to benefit from binaural advantages under reverberant conditions. Another aim of this contribution was to determine whether the magnitude of each binaural advantage observed inside a highly reverberant environment differs significantly from the magnitude measured in a near-anechoic environment. Method: Ten adults with postlingual deafness who are bilateral CI users fitted with either Nucleus 5 or Nucleus 6 clinical sound processors (Cochlear Corporation) participated in this study. Speech reception thresholds were measured in sound field and 2 different reverberation conditions (0.06 and 0.6 s) as a function of the listening condition (left, right, both) and the noise spatial location (left, front, right). Results: The presence of the binaural effects of head-shadow, squelch, summation, and spatial release from masking in the 2 different reverberation conditions tested was determined using nonparametric statistical analysis. In the bilateral population tested, when the ambient reverberation time was equal to 0.6 s, results indicated strong positive effects of head-shadow and a weaker spatial release from masking advantage, whereas binaural squelch and summation contributed no statistically significant benefit to bilateral performance under this acoustic condition. These findings are consistent with those of previous studies, which have demonstrated that head-shadow yields the most pronounced advantage in noise. The finding that spatial release from masking produced little to almost no benefit in bilateral listeners is consistent with the hypothesis that additive reverberation degrades spatial cues and negatively affects binaural performance. Conclusions: The magnitude of 4 different binaural advantages was measured on the same group of bilateral CI subjects fitted with clinical processors in 2 different reverberation conditions. The results of this work demonstrate the impeding properties of reverberation on binaural speech understanding. In addition, results indicate that CI recipients who struggle in everyday listening environments are also more likely to benefit less in highly reverberant environments from their bilateral processors. [ABSTRACT FROM AUTHOR]