Neural envelope tracking predicts speech intelligibility and hearing aid benefit in children with hearing loss

Early assessment of hearing aid benefit is crucial, as the extent to which hearing aids provide audible speech information predicts speech and language outcomes. A growing body of research has proposed neural envelope tracking as an objective measure of speech intelligibility, particularly for individuals unable to provide reliable behavioral feedback. However, its potential for evaluating speech intelligibility and hearing aid benefit in children with hearing loss remains unexplored. In this study, we investigated neural envelope tracking in children with permanent hearing loss through two separate experiments. EEG data were recorded while children listened to age-appropriate stories (Experiment 1) or an animated movie (Experiment 2) under aided and unaided conditions (using personal hearing aids) at multiple stimulus intensities. Neural envelope tracking was evaluated using a linear decoder reconstructing the speech envelope from the EEG in the delta band (0.5-4 Hz). Additionally, we calculated temporal response functions (TRFs) to investigate the spatio-temporal dynamics of the response. In both experiments, neural tracking increased with increasing stimulus intensity, but only in the unaided condition. In the aided condition, neural tracking remained stable across a wide range of intensities, as long as speech intelligibility was maintained. Similarly, TRF amplitudes increased with increasing stimulus intensity in the unaided condition, while in the aided condition significant differences were found in TRF latency rather than TRF amplitude. This suggests that decreasing stimulus intensity does not necessarily impact neural tracking. Furthermore, the use of personal hearing aids significantly enhanced neural envelope tracking, particularly in challenging speech conditions that would be inaudible when unaided. Finally, we found a strong correlation between neural envelope tracking and behaviorally measured speech intelligibility for both narrated stories (Experiment 1) and movie stimuli (Experiment 2). Altogether, these findings indicate that neural envelope tracking could be a valuable tool for predicting speech intelligibility benefits derived from personal hearing aids in hearing-impaired children. Incorporating narrated stories or engaging movies expands the accessibility of these methods even in clinical settings, offering new avenues for using objective speech measures to guide pediatric audiology decision-making.

Delta-band neural envelope tracking predicts speech intelligibility in noise in preschoolers

Behavioral tests are currently the gold standard in measuring speech intelligibility. However, these tests can be difficult to administer in young children due to factors such as motivation, linguistic knowledge and cognitive skills. It has been shown that measures of neural envelope tracking can be used to predict speech intelligibility and overcome these issues. However, its potential as an objective measure for speech intelligibility in noise remains to be investigated in preschool children. Here, we evaluated neural envelope tracking as a function of signal-to-noise ratio (SNR) in 14 5-year-old children. We examined EEG responses to natural, continuous speech presented at different SNRs ranging from -8 (very difficult) to 8 dB SNR (very easy). As expected delta band (0.5-4 Hz) tracking increased with increasing stimulus SNR. However, this increase was not strictly monotonic as neural tracking reached a plateau between 0 and 4 dB SNR, similarly to the behavioral speech intelligibility outcomes. These findings indicate that neural tracking in the delta band remains stable, as long as the acoustical degradation of the speech signal does not reflect significant changes in speech intelligibility. Theta band tracking (4-8 Hz), on the other hand, was found to be drastically reduced and more easily affected by noise in children, making it less reliable as a measure of speech intelligibility. By contrast, neural envelope tracking in the delta band was directly associated with behavioral measures of speech intelligibility. This suggests that neural envelope tracking in the delta band is a valuable tool for evaluating speech-in-noise intelligibility in preschoolers, highlighting its potential as an objective measure of speech in difficult-to-test populations.

Ahead of maturation: Enhanced speech envelope training boosts rise time discrimination in pre-readers at cognitive risk for dyslexia

Dyslexia has frequently been related to atypical auditory temporal processing and speech perception. Results of studies emphasizing speech onset cues and reinforcing the temporal structure of the speech envelope, that is, envelope enhancement (EE), demonstrated reduced speech perception deficits in individuals with dyslexia. The use of this strategy as auditory intervention might thus reduce some of the deficits related to dyslexia. Importantly, reading-skill interventions are most effective when they are provided during kindergarten and first grade. Hence, we provided a tablet-based 12-week auditory and phonics-based intervention to pre-readers at cognitive risk for dyslexia and investigated the effect on auditory temporal processing with a rise time discrimination (RTD) task. Ninety-one pre-readers at cognitive risk for dyslexia (aged 5-6) were assigned to two groups receiving a phonics-based intervention and playing a story listening game either with (n = 31) or without (n = 31) EE or a third group playing control games and listening to non-enhanced stories (n = 29). RTD was measured directly before, directly after and 1 year after the intervention. While the groups listening to non-enhanced stories mainly improved after the intervention during first grade, the group listening to enhanced stories improved during the intervention in kindergarten and subsequently remained stable during first grade. Hence, an EE intervention improves auditory processing skills important for the development of phonological skills. This occurred before the onset of reading instruction, preceding the maturational improvement of these skills, hence potentially giving at risk children a head start when learning to read.

Temporal quantization deteriorates the discrimination of interaural time differences

Cochlear implants (CIs) often replace acoustic temporal fine structure by a fixed-rate pulse train. If the pulse timing is arbitrary (that is, not based on the phase information of the acoustic signal), temporal information is quantized by the pulse period. This temporal quantization is probably imperceptible with current clinical devices. However, it could result in large temporal jitter for strategies that aim to improve bilateral and bimodal CI users' perception of interaural time differences (ITDs), such as envelope enhancement. In an experiment with 16 normal-hearing listeners, it is shown that such jitter could deteriorate ITD perception for temporal quantization that corresponds to the often-used stimulation rate of 900 pulses per second (pps): the just-noticeable difference in ITD with quantization was 177 μs as compared to 129 μs without quantization. For smaller quantization step sizes, no significant deterioration of ITD perception was found. In conclusion, the binaural system can only average out the effect of temporal quantization to some extent, such that pulse timing should be well-considered. As this psychophysical procedure was somewhat unconventional, different procedural parameters were compared by simulating a number of commonly used two-down one-up adaptive procedures in Appendix B.

Utility of 123I-FP-CIT SPECT for dementia diagnoses and therapeutic strategies in elderly patients

OBJECTIVES

Evaluation of the influence of single photon emission computed tomography (SPECT) of the dopamine transporter (123I-FP-CIT) on diagnosis and treatment strategies in elderly patients with mild dementia.

DESIGN

Retrospective study.

SETTING

Geriatrics memory clinic.

PARTICIPANTS

Consecutive ambulatory patients who had 123I-FP-CIT SPECT for a suspicion of DLB.

MEASUREMENTS

Clinical diagnoses before SPECT were compared with imaging results.

RESULTS

46 patients were included. Pre imaging clinical hypotheses were probable DLB in 14, possible DLB in 21 and alternate diagnoses in 11. Rates of abnormal imaging in these groups were respectively 71%, 43% and 18%. Overall, diagnoses were revised in 37% of the cases. Four patients with probable DLB had normal imaging. Their number of core criteria did not differ from the remainder (2.75 ± 0.5 vs. 2.1 ± 0.6), but hallucinations in 2 patients were not well formed and detailed as usual in DLB. Among 38 patients free of antipsychotics, rates of abnormal scans were 36% in patients with questionable parkinsonism, 57% in definite parkinsonism, 67% in patients with no parkinsonism. Among 9 patients on Levodopa, 6 had normal scans and Levodopa was stopped.

CONCLUSION

We show a significant impact of 123I-FP-CIT SPECT on diagnoses, even in cases of definite parkinsonism or probable DLB. In the latter, scarcity of hallucinations, especially if there are not well formed and detailed, should prompt 123I-FP-CIT SPECT.

Comorbidités et maladie d'Alzheimer : données à l'inclusion de la cohorte gériatrique REAL.FR

PURPOSE

Alzheimer's disease (AD) evolves over about ten years with cognitive decline that can be considered as linear. Comorbidities are frequent in geriatric population. The major objective of this study is to determine whether comorbidity influences natural history of AD.

MATERIALS AND METHODS

This is a prospective, multicentric French study (REAL.FR) of a cohort of ambulatory patients suffering from AD from a mild to a moderately severe stage, with a Mini-Mental State between 10 and 26, and followed with a caregiver. We evaluated the comorbidities and they were quantified using the Charlson index.

RESULTS

We analysed 579 AD patients enrolled between April 2000 and June 2002. Majority of patients were women (72%). Average age and MMS average score were respectively 77.4 +/- 7.1 and 20.1 +/- 4.5. Cardiovascular diseases were the most frequent comorbid conditions (34%), before sensorial handicap (23%), and neurological diseases (18%) apart from dementia. Four AD patients groups differed according to the comorbidities figures, from none to more than three (maximum 8). Average Charlson index was 1.5 +/- 0.9.

CONCLUSION

The follow-up of the four AD patients groups, differentiated by the comorbidities figures, should allow to precise the influence of comorbidities on the AD evolution. Charlson index could be used to quantify the comorbidities in the cohort's follow-up. However, this index, validated in a cohort of cancer patients, show limits for its use in geriatric population.

[Clinical features of ambulatory patients over 80 years of age followed for Alzheimer's disease. French prospective multicenter study REAL.FR]

PURPOSE

Twice out off three, patients with Alzheimer's disease (AD) are aged 80 and older. Very old patients are more frail, have social precariousness and have often polypathology. Few data are available about these elderly patients. The aim of our study was to analyse characteristics of AD patients aged 80 and older.

MATERIAL AND METHODS

This is a prospective, multicentric French study (REAL.FR) of a cohort of ambulatory AD patients, with Mini-Mental State values between 10 and 26. Clinical and social data at inclusion of patients aged 80 and older and patients younger were compared.

RESULTS

Six hundred eighty nine patients (488 women, 201 men) were included between April 2000 and June 2002. The mean age was 77.8 +/- 6.9 years. Two hundred sixty four patients (38%) were aged 80 and older. Those patients were more dependant for Activities of Daily Living (ADL) than younger patients (ADL score of Katz: 5.2 +/- 1.07 et 5.6 +/- 0.74 respectively; p < 0.001 and IADL (Instrumental Activities of Daily Living) score of Lawton: 7.3 +/- 3.57 et 9.3 +/- 1.57 respectively; p < 0.001). Duration of evolution of the disease were comparable between older and younger patients.

CONCLUSION

In our cohort, AD patients aged 80 and older had a weakest autonomy for the ADL than younger patients with the same stage of the disease. Results has implications on care. Following the cohort will permit to specify evolution of data.

Role of behavioural disturbance in the loss of autonomy for activities of daily living in Alzheimer patients

BACKGROUND

Cognitive impairment is associated with functional impairment in patients with Alzheimer's disease (AD). Behavioural disturbance is very common in these patients. Nevertheless, there has been very little research into the relations between behavioural disturbance and functional status in AD. The purpose of this study is to investigate the relationship between behavioural disturbance and functional status after taking account of cognitive impairment.

MATERIAL AND METHODS

579 patients were prospectively evaluated at 16 French hospitals, all referents for AD, and were diagnosed with possible or probable AD. These patients were assessed with NeuroPsychiatric Inventory (NPI), cognitive subscales of the Alzheimer's Disease Assessment Scale (ADAS-cog), Clinical Dementia Rating scale (CDR) and Instrumental Activities of Daily Living scale (IADL).

RESULTS

The number of men with available data for IADL total score was too small to make any analysis. 'Group A' gathered 256 women for whom the relation between autonomy for Activities of Daily Living (ADL) and the other variables were determined. 'Group B', pooled 85 women for whom relations found were verified. Linear regression was used for the analysis. With age, cognitive impairment allows us to explain best (38%) the loss of autonomy for ADL.

CONCLUSION

The role of behavioural disturbances in the loss of autonomy for ADL was not determinant in our study, whereas cognitive impairment and age were better able to determine the loss of autonomy for ADL. Further study is needed to explain the decline of functional status in AD patients.

The application of the theoretical model WHO/FDI planning system to an industrialised country: France

The results of the application of the WHO/FDI planning system to a specific situation in an industrialised country provide valid arguments in favour of its use. It is shown to be an aid to planners when estimating oral health personnel requirements and emphasises the necessity of obtaining basic information on the oral health status and demand for treatment in industrialised countries. The strength of the system lies in the fact that it enables the user to forecast requirements, by age cohort and by type of care, while at the same time including socio-economic variables which have a major influence in industrialised countries with moderate caries levels. This flexibility of use enables the system to be adapted, if necessary, or even improved, according to the constraints which may result from a specific situation analysis.