The use of functional magnetic resonance imaging (fMRI) to explore central auditory function may be compromised by the intense bursts of stray acoustic noise produced by the scanner whenever the magnetic resonance signal is read out. We present results evaluating the use of one method to reduce the effect of the scanner noise: "sparse" temporal sampling. Using this technique, single volumes of brain images are acquired at the end of stimulus and baseline conditions. To optimize detection of the activation, images are taken near to the maxima and minima of the hemodynamic response during the experimental cycle. Thus, the effective auditory stimulus for the activation is not masked by the scanner noise. In experiment 1, the course of the hemodynamic response to auditory stimulation was mapped during continuous task performance. The mean peak of the response was at 10.5 sec after stimulus onset, with little further change until stimulus offset. In experiment 2, sparse imaging was used to acquire activation images. Despite the fewer samples with sparse imaging, this method successfully delimited broadly the same regions of activation as conventional continuous imaging. However, the mean percentage MR signal change within the region of interest was greater using sparse imaging. Auditory experiments that use continuous imaging methods may measure activation that is a result of an interaction between the stimulus and task factors (e.g., attentive effort) induced by the intense background noise. We suggest that sparse imaging is advantageous in auditory experiments as it ensures that the obtained activation depends on the stimulus alone.

Objective To estimate the prevalence of confirmed permanent childhood hearing impairment and its profile across age and degree of impairment in the United Kingdom. Design Retrospective total ascertainment through sources in the health and education sectors by postal questionnaire. Setting Hospital based otology and audiology departments, community health clinics, education services for hearing impaired children.

More quality of life is likely to be gained per unit of expenditure on unilateral implantation than bilateral implantation.

Compared with unilateral cochlear implantation, bilateral implantation is associated with better listening skills in severely-profoundly deaf children.

Objectives: The objectives of this study were to identify variables which are associated with differences in outcome among hearing-impaired children, and to control those variables while assessing the impact of cochlear implantation. Study design:In a cross-sectional study, the parents and teachers of a representative sample of hearing-impaired children were invited to complete questionnaires about children's auditory performance, spoken communication skills, educational achievements, and quality of life. Multiple regression was used to measure the strength of association between these outcomes and variables related to the child (average hearing level, age at onset of hearing impairment, age, gender, number of additional disabilities), the family (parental occupational skill level, ethnicity, and parental hearing status), and cochlear implantation.Results: Questionnaires were returned by the parents of 2858 children, 468 of whom had received a cochlear implant, and by the teachers of 2241 children, 383 of whom had received an implant. Across all domains, reported outcomes were better for children with fewer disabilities in addition to impaired hearing. Across most domains, reported outcomes were better for children who were older, female, with a more favourable average hearing level, with a higher parental occupational skill level, and with an onset of hearing-impairment after 3 years. When these variables were controlled, cochlear implantation was consistently associated with advantages in auditory performance and spoken communication skills, but less consistently associated with advantages in educational achievements and quality of life.Significant associations were found most commonly for children who were younger than 5 years when implanted, and had used implants for more than 4 years. TheseHearing-impaired children in the UK, I. 2 children, whose mean (pre-operative, un-aided) average hearing level was 118 dB, performed at the same level as non-implanted children with average hearing levels in the range from 80 dB to 104 dB, depending on the outcome measure. Conclusion:When rigorous statistical control is exercised in comparing implanted and non-implanted children, paediatric cochlear implantation is associated with reported improvements both in spoken communication skills and in some aspects of educational achievements and quality of life, provided that children receive implants before 5 years of age.(342 words)

Adult users of unilateral Nucleus CI24 cochlear implants with the SPEAK processing strategy were randomised either to receive a second identical implant in the contralateral ear immediately, or to wait 12 months while they acted as controls for late-emerging benefits of the first implant. Twenty four subjects, twelve from each group, completed the study. Receipt of a second implant led to improvements in self-reported abilities in spatial hearing, quality of hearing, and hearing for speech, but to generally non-significant changes in measures of quality of life. Multivariate analyses showed that positive changes in quality of life were associated with improvements in hearing, but were offset by negative changes associated with worsening tinnitus. Even in a best-case scenario, in which no worsening of tinnitus was assumed to occur, the gain in quality of life was too small to achieve an acceptable cost-effectiveness ratio. The most promising strategies for improving the cost-effectiveness of bilateral implantation are to increase effectiveness through enhanced signal processing in binaural processors, and to reduce the cost of implant hardware.

Listeners are able to extract important linguistic information by viewing the talker's face -a process known as 'speechreading'. Previous studies of speechreading present small closed sets of simple words and their results indicate that visual speech processing engages a wide network of brain regions in the temporal, frontal, and parietal lobes that are likely to underlie multiple stages of the receptive language system. The present study further explored this network in a large group of subjects by presenting naturally-spoken sentences which tap the richer complexities of visual speech processing. Four different baselines (blank screen, static face, non-linguistic facial gurning, and auditory speech) enabled us to determine the hierarchy of neural processing involved in speechreading and to test the claim that visual input reliably accesses sound-based representations in the auditory cortex.In contrast to passively viewing a blank screen, the static-face condition evoked activation bilaterally across the border of the fusiform gyrus and cerebellum, and in the medial superior frontal gyrus and left precentral gyrus (P < 0.05, whole brain corrected). With the static face as baseline, the gurning face evoked bilateral activation in the motion-sensitive region of the occipital cortex, whereas visual speech additionally engaged middle temporal 1 gyrus, inferior and middle frontal gyri, and the inferior parietal lobe, particularly in the left hemisphere. These latter regions are implicated in lexical stages of spoken language processing. While auditory speech generated extensive bilateral activation across both superior and middle temporal gyri, the group-averaged pattern of speechreading activation failed to include any auditory regions along the superior temporal gyrus, suggesting that fluent visual speech does not always involve sound-based coding of the visual input.An important finding from the individual subject analyses was that activation in the superior temporal gyrus did reach significance (P < 0.001, small-volume corrected) for a subset of the group. Moreover, the extent of the left-sided superior temporal gyrus activity was strongly correlated with speechreading performance. Skilled speechreading was also associated with activations and deactivations in other brain regions suggesting that individual differences reflect the efficiency of a circuit linking sensory, perceptual, memory, cognitive, and linguistic processes rather than the operation of a single component process.

Hierarchical processing suggests that spectrally and temporally complex stimuli will evoke more activation than do simple stimuli, particularly in non-primary auditory fields. This hypothesis was tested using two tones, a single frequency tone and a harmonic tone, that were either static or frequency modulated to create four stimuli. We interpret the location of differences in activation by drawing comparisons between fMRI and human cytoarchitectonic data, reported in the same brain space. Harmonic tones produced more activation than single tones in right Heschl's gyrus (HG) and bilaterally in the lateral supratemporal plane (STP). Activation was also greater to frequency-modulated tones than to static tones in these areas, plus in left HG and bilaterally in an anterolateral part of the STP and the superior temporal sulcus. An elevated response magnitude to both frequency-modulated tones was found in the lateral portion of the primary area, and putatively in three surrounding non-primary regions on the lateral STP (one anterior and two posterior to HG). A focal site on the posterolateral STP showed an especially high response to the frequency-modulated harmonic tone. Our data highlight the involvement of both primary and lateral non-primary auditory regions.