Speech-Identification During Standing as a Multitasking Challenge for Young, Middle-Aged and Older Adults.

While listening, we commonly participate in simultaneous activities. For instance, at receptions people often stand while engaging in conversation. It is known that listening and postural control are associated with each other. Previous studies focused on the interplay of listening and postural control when the speech identification task had rather high cognitive control demands. This study aimed to determine whether listening and postural control interact when the speech identification task requires minimal cognitive control, i.e., when words are presented without background noise, or a large memory load. This study included 22 young adults, 27 middle-aged adults, and 21 older adults. Participants performed a speech identification task (auditory single task), a postural control task (posture single task) and combined postural control and speech identification tasks (dual task) to assess the effects of multitasking. The difficulty levels of the listening and postural control tasks were manipulated by altering the level of the words (25 or 30 dB SPL) and the mobility of the platform (stable or moving). The sound level was increased for adults with a hearing impairment. In the dual-task, listening performance decreased, especially for middle-aged and older adults, while postural control improved. These results suggest that even when cognitive control demands for listening are minimal, interaction with postural control occurs. Correlational analysis revealed that hearing loss was a better predictor than age of speech identification and postural control.

Multitasking across the lifespan in different task contexts.

We assessed lifespan development of multitasking in a sample of 187 individuals aged 8-82 years. Participants performed a visuo-spatial working memory (VSWM) task together with either postural control or reaction time (RT) tasks. Using criterion-referenced testing we individually adjusted difficulty levels for the VSWM task to control for single-task differences. Age-differences in single-task performances followed U-shaped patterns with young adults outperforming children and older adults. Multitasking manipulations yielded robust performance decrements in VSWM, postural control and RT tasks. Presumably due to our adjustment of VSWM challenges, costs in this task were small and similar across age groups suggesting that age-differential costs found in earlier studies largely reflected differences already present during single-task performance. Age-differences in multitasking costs for concurrent tasks depended on specific combinations. For VSWM and RT task combinations increases in RT were the smallest for children but pronounced in adults highlighting the role of cognitive control processes. Stabilogram diffusion analysis of postural control demonstrated that long-term control mechanisms were affected by concurrent VSWM demands. This interference was pronounced in older adults supporting concepts of compensation or increased cognitive involvement in sensorimotor processes at older age. Our study demonstrates how a lifespan approach can delineate the explanatory scope of models of human multitasking.

Effectiveness of Auditory Training in Experienced Hearing-Aid Users, and an Exploration of Their Health-Related Quality of Life and Coping Strategies.

Hearing aids (HA) are a fundamental component in restoring auditory function; however, they cannot completely alleviate all problems encountered by adults with hearing impairment. The aim of this study is twofold. Firstly, we assess the health-related quality of life and coping strategies of experienced HA users. Secondly, we assess whether HA users can benefit from auditory training. To this end, 40 participants who had worn HAs for more than 6 months participated in this study. Half of the participants received auditory training, while the other half served as a passive control. The training consisted of a personalized training scheme, with outcome measures including speech in noise perception in free-field and via direct streaming to the HA, phoneme identification, cognitive control, and health-related quality of life. Results showed that experienced HA users reported a relatively good quality of life. Health-related quality of life was correlated with aided speech perception in noise, but not with aided pure tone audiometry. Coping strategies were adaptive, leading to improved communication. Participants showed improvements in trained tasks, consonant identification, and speech in noise perception. While both groups yielded improved speech in noise perception at the end, post hoc analysis following a three-way interaction showed a significantly larger pre-post difference for the trained group in the streaming condition. Although training showed some improvements, the study suggests that the training paradigm was not sufficiently challenging for HA users. To optimize daily life listening, we recommend that future training should incorporate more exercises in noise and focus on cognitive control.

Toward a Listening Training Paradigm: Evaluation in Normal-Hearing Young and Middle-Aged Adults.

OBJECTIVES: Adults' most common complaint relates to understanding speech in noisy environments. Hearing aids can compensate for sensory loss but do not restore hearing to normal. Listening training has the potential to partially remediate these problems. In this study, we propose and evaluate a Flemish version of a listening training paradigm, which involves the use of cognitive control as well as auditory perception. The paradigm entails a discrimination task where participants are cued to attend to one of two concurrent talkers with target speakers randomly varying between a female and a male voice. We evaluate learning effects, different scenarios, and masking types. DESIGN: In total, 70 young and 54 middle-aged adults participated in this study. Each adult performed one or more conditions. Participants' hearing was screened before participation, all middle-aged adults passed a cognitive screening task. RESULTS: Analyses indicated learning effects across scenarios that were similar in terms of speech intelligibility. Our results indicated better speech intelligibility when the female speaker was the target, but speech intelligibility did not differ when the target was the male speaker. An unintelligible masker noise results in worse speech intelligibility than a competing talker masker. Our results suggest that listeners could use an intensity cue to identify and/or select the target speaker when presented at a lower signal to noise ratio (SNR). Error analysis suggested higher cognitive control demands when the target and masker were presented at similar levels (i.e., around 0 dB SNR). The addition of independent trials with the intensity of target and masker reversed improved speech intelligibility. Inhibitory control, but not task switching, was reliably correlated with listening performance. CONCLUSIONS: The proposed paradigm turned out to be feasible and practicable, demonstrating its potential for training speech intelligibility in noise. We believe that this training paradigm can generate real-life benefits including for persons with hearing loss. This latter application awaits future evaluation.

Coupling of sensorimotor and cognitive functions in middle- and late adulthood.

Introduction: The present study explored age effects and the coupling of sensorimotor and cognitive functions in a stratified sample of 96 middle-aged and older adults (age 45-86 years) with no indication of mild cognitive decline. In our sensorimotor tasks, we had an emphasis on listening in noise and postural control, but we also assessed functional mobility and tactile sensitivity. Methods: Our cognitive measures comprised processing speed and assessments of core cognitive control processes (executive functions), notably inhibition, task switching, and working memory updating. We explored whether our measures of sensorimotor functioning mediated age differences in cognitive variables and compared their effect to processing speed. Subsequently, we examined whether individuals who had poorer (or better) than median cognitive performance for their age group also performed relatively poorer (or better) on sensorimotor tasks. Moreover, we examined whether the link between cognitive and sensorimotor functions becomes more pronounced in older age groups. Results: Except for tactile sensitivity, we observed substantial age-related differences in all sensorimotor and cognitive variables from middle age onward. Processing speed and functional mobility were reliable mediators of age in task switching and inhibitory control. Regarding coupling between sensorimotor and cognition, we observed that individuals with poor cognitive control do not necessarily have poor listening in noise skills or poor postural control. Discussion: As most conditions do not show an interdependency between sensorimotor and cognitive performance, other domain-specific factors that were not accounted for must also play a role. These need to be researched in order to gain a better understanding of how rehabilitation may impact cognitive functioning in aging persons.

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.