Antje Heinrich

Investigating the influence of continuous babble on auditory short-term memory performance

A number of factors could explain the adverse effect that babble noise has on memory for spoken words (Murphy, Craik, Li, & Schneider, 2000). Babble could degrade the perceptual representation of words to such an extent that it compromises their subsequent processing, or the presence of speech noise in the period between word presentations could interfere with rehearsal. Thirdly, the top-down processes needed to extract the words from the babble could draw on resources that otherwise would be used for encoding. We tested all these hypotheses by presenting babble either only during word presentation or rehearsal, or by gating the babble on and off 500 ms before and after each word pair. Only the last condition led to a decline in memory. We propose that this decline in memory occurred because participants were focusing their attention on the auditory stream (to enable them to better segregate the words from the noise background) rather than on remembering the words they had heard. To further support our claim we show that a similar memory deficit results when participants perform the same memory task in quiet together with a nonauditory attention-demanding secondary task.

Within- and between-channel gap detection in the human auditory cortex.

We examined the neural correlates associated with a short gap between two identical pure tones (within-channel) and between two different tones (between-channel) in an odd-ball paradigm. Gap durations were selected such that a gap between identical tones was as discriminable as a gap between two different tones. Spatio-temporal dipole source modeling of electrophysiological data revealed a significant difference between standard and deviant gap stimuli, with mismatch negativity responses that were comparable in amplitude and latency for within- and between-channel conditions. Therefore, the ability to automatically register discontinuity (i.e., gap) within and between channels is comparable despite significant differences in gap size. The dipole source modeling suggests that both within- and between-gap signals are represented in or near the primary auditory cortex.

Age-related changes in within- and between-channel gap detection using sinusoidal stimuli

Pure tone gap stimuli with identical (within-channel) or dissimilar (between-channel) marker frequencies of 1 and 2 kHz were presented to young and old listeners in a two-interval forced choice gap detection task. To estimate the influence of extraneous duration cues on gap detection, thresholds in the between-channel conditions were obtained for two different sets of reference stimuli: reference stimuli that were matched to the overall duration of the gap stimulus, i.e., two markers plus the gap, and reference stimuli that were fixed at the combined duration of the two markers excluding the gap. Results from within-channel conditions were consistent with previous studies, i.e., there were small but highly reliable age differences, smaller gap thresholds at longer marker durations, and an interaction between the two variables. In between-channel conditions, however, age differences were not as clear cut. Rather, the effect of age varied as a function of duration cue and was more pronounced when stimuli were matched for overall duration than when the duration of the reference tone was fixed.

Elucidating the effects of ageing on remembering perceptually distorted word pairs

We investigated the effects of age, background babble, and acoustic distortion of the word itself on serial position memory in a series of experiments involving six different auditory environments (quiet, and 12-talker background babble presented between, overlapping, or concurrent with word presentation or with two kinds of distortion applied to the words). To control for hearing, the level of babble or distortion was adjusted so that younger and older adults could hear the words equally well. Although the presence of continuous and word-flanking background babble adversely affected memory in the early serial positions in both age groups, only older adults’ memory was adversely affected in the later serial positions. Moreover, younger adults’ memory was not affected by acoustic word distortion, whereas one of the two types of temporal distortion adversely affected memory for later serial positions in older adults. The exact pattern of impairment and its interaction with age suggests that memory in older adults is more affected than that in younger adults in complex listening situations because they either need more time or have to employ more attentional resources to segregate different auditory streams, thereby depleting the pool of resources available for memory encoding.

Iconic Sign Comprehension in Older Adults: The Role of Cognitive Impairment and Text Enhancement.

Bien comprendre les panneaux de signalisation est critique pour bien conduire aun véhicule, réagir aux avertissements, et s’orienter. Les aînés qui comprennent mal un panneau routier risquent davantage de subir un accident et de voir leur indépendance compromise. La présente étude visait à déterminer le degré de compréhension des pictogrammes par des aînés en bonne santé et des aînés souffrant de déficience. De plus, nous nous sommes demandé si l’ajout de texte aux pictogrammes permettrait aux aînés de les mieux comprendre. Lors de l’Expérience 1, nous avons demandé à des jeunes adultes, à des adultes plus âgés en bonne santé et aussi à des aînés souffrant de déficience cognitive à divers degrés, la signification de 65 panneaux routiers visant la conduite, les avertissements, et l’orientation. Les adultes plus âgés en bonne santé comprenaient bien la signalisation en général, mais avaient de la difficulté à déterminer ce que signifiait le panneau d’orientation. Les aînés souffrant de déficience cognitive comprenaient en général moins bien les panneaux routiers et en particulier les icônes d’orientation et les panneaux avec seulement un pictogramme. Au cours de l’Expérience 2, nous avons demandé à des aînés en bonne santé la signification de panneaux comportant seulement des icônes ou des icônes avec du texte. La compréhension était améliorée de façon importante lorsque le panneau comportait du texte. Ce travail a démontré que l’évaluation de la compréhension des panneaux de signalisation doit porter sur un vaste échantillon hétérogène d’adultes plus âgés dans l’échelle de capacités perceptuelles et cognitives représentées dans la population.In response to the contradictions appearing between, on the one hand, government promotion of family caregiving for elderly parents and, on the other, the rise of autonomist values (as documented in the literature), we surveyed a number of elderly people living with disabilities about the kind of assistance they would like to receive. The present qualitative, thematic analysis is based on the accounts given by 19 elderly people who receive assistance. The findings show that the position of elderly people with respect to their desire to receive (or not receive) substantial assistance from their family rests on a set of values, wishes, and/or fears – including, particularly, adherence to the value of autonomy, the desire to respect freedom (one’s own as well as that of others), adherence to norms of familial duty, attachment to one’s home, the value placed on solitude and privacy, and the degree of emotional closeness between the elderly and their children. Access to quality formal services also stands out as a factor enabling elderly people to actualize the desire for care which they elicited within the framework of this analysis.

The effect of presentation level on memory performance.

Objectives: A loss of speech intelligibility at high presentation levels is called rollover. It is a phenomenon that increases in prevalence as people age. Whether the adverse effect of high presentation levels extends to processes subsequent to speech intelligibility, such as memory, is unknown. The present study examined this question on the basis of the previous finding that older but not younger adults showed memory impairment when acoustically distorted words were presented at 50 dB SL compared with an undistorted baseline presented at 65 dB SPL. One question investigated in the present study was whether a presentation level of 50 dB SL put older listeners at the cusp of rollover and whether this subsequently impaired memory. Moreover, we wanted to know whether and at what level it was possible to induce a similar impairment in younger listeners. Design: We used a paired-associate memory paradigm in which five word pairs per list were presented at a rate of 4 secs per word pair. After each list, the first word of one of the pairs was presented again and the listener was asked to recall the second word. Over the course of the experiment, all list positions were tested an equal number of times. The word pairs, which were acoustically distorted using a jittering algorithm, were presented at 40 dB SL to all younger and older participants and just below an uncomfortably loud level for younger listeners only. Intelligibility of the distorted words was equated across age groups for each presentation level. The effect of presentation level on memory performance was investigated and compared with data of a previous study that used the same design but presented the distorted and undistorted words at 50 dB SL to both age groups. A total of 58 younger and 24 older adults were tested in two experiments. Results: The results showed that for older adults, memory performance for distorted words was decreased in all list positions at a presentation level of 50 dB SL compared with 40 dB SL and an undistorted 65 dB SPL baseline. This effect did not occur for younger listeners. However, when younger adults were tested at a very high presentation level, they showed the same memory decrease compared with the baseline as older adults showed for 50 dB SL. Conclusions: A high presentation level of distorted words can adversely affect memory even after intelligibility is equated for. Moreover, older listeners are affected at lower presentation levels. Hence, the choice of sound level, particularly for older listeners, is important and may affect their level of cognitive performance beyond its effects on intelligibility. Higher presentation levels may not always lead to better performance when the task involves recall of words previously heard.

Objective Measures of Auditory Scene Analysis

We describe objective measures of two aspects of auditory scene analysis (ASA). We show that the build-up of auditory streaming can be measured using a behavioural task - detection of a temporal shift of one tone relative to another - that is easiest when the two tones are part of the same stream. This paradigm is used to show that performance can be improved by requiring participants to briefly divert their attention away from the tones, a manipulation that has previously been shown to increase the number of “one stream” judgements in a subjective task. A physiological measure of streaming build-up is also obtained using the mismatch negativity paradigm. In contrast to the strong effects of attention on streaming, we show, using fMRI measures of the brain response to veridical and illusory vowels, that the continuity illusion does not depend strongly on attention.

Effective Communication as a Fundamental Aspect of Active Aging and Well-Being: Paying Attention to the Challenges Older Adults Face in Noisy Environments

Successful communication is vital to active aging and well-being, yet virtually all older adults find it challenging to communicate effectively in noisy environments. The resulting discomfort and frustration can prompt withdrawal or avoidance of social situations, which, in turn, can severely limit the range of activities available to older adults and lead to a less active and satisfying lifestyle, and, in some cases, depression. Using the International Classification of Functioning, Disability and Health’s (ICF) multifactorial model (WHO, 2001), we review the wider aspects of functioning and disability as they relate to hearing difficulties and communication, placing a particular emphasis on the work we, an international and interdisciplinary group of researchers, have done in the context of the ERA-NET funded interdisciplinary HEARATTN project. The ICF model is particularly fitting because it allows us to consider how physiological changes in hearing and cognition affect listening in various situations, what the consequences of these changes are for communicative abilities and social participation, and how this in turn affects life-space mobility, self-reported well-being, and, ultimately, quality of life. We will discuss how environmental conditions (both physical and social) and personal factors can affect how well older adults can communicate in the situations characteristic of everyday life. In the concluding section we discuss some behaviors, techniques and strategies that can be adopted to maintain or improve effective communication under difficult listening conditions.

The Contribution of Auditory and Cognitive Factors to Intelligibility of Words and Sentences in Noise.

Understanding the causes for speech-in-noise (SiN) perception difficulties is complex, and is made even more difficult by the fact that listening situations can vary widely in target and background sounds. While there is general agreement that both auditory and cognitive factors are important, their exact relationship to SiN perception across various listening situations remains unclear. This study manipulated the characteristics of the listening situation in two ways: first, target stimuli were either isolated words, or words heard in the context of low- (LP) and high-predictability (HP) sentences; second, the background sound, speech-modulated noise, was presented at two signal-to-noise ratios. Speech intelligibility was measured for 30 older listeners (aged 62-84) with age-normal hearing and related to individual differences in cognition (working memory, inhibition and linguistic skills) and hearing (PTA(0.25-8 kHz) and temporal processing). The results showed that while the effect of hearing thresholds on intelligibility was rather uniform, the influence of cognitive abilities was more specific to a certain listening situation. By revealing a complex picture of relationships between intelligibility and cognition, these results may help us understand some of the inconsistencies in the literature as regards cognitive contributions to speech perception.

The role of stimulus complexity, spectral overlap, and pitch for gap-detection thresholds in young and old listeners

Thresholds for detecting a gap between two complex tones were determined for young listeners with normal hearing and old listeners with mild age-related hearing loss. The leading tonal marker was always a 20-ms, 250-Hz complex tone with energy at 250, 500, 750, and 1000u2009Hz. The lagging marker, also tonal, could differ from the leading marker with respect to fundamental frequency (f0), the presence versus absence of energy at f0, and the degree to which it overlapped spectrally with the leading marker. All stimuli were presented with steeper (1u2009ms) and less steep (4u2009ms) envelope rise and fall times. F0 differences, decreases in the degree of spectral overlap between the markers, and shallower envelope shape all contributed to increases in gap-detection thresholds. Age differences for gap detection of complex sounds were generally small and constant when gap-detection thresholds were measured on a log scale. When comparing the results for complex sounds to thresholds obtained for pure-tones in a previous study by Heinrich and Schneider [(2006). J. Acoust. Soc. Am. 119, 2316-2326], thresholds increased in an orderly fashion from markers with identical (within-channel) pure tones to different (between-channel) pure tones to complex sounds. This pattern of results was true for listeners of both ages although younger listeners had smaller thresholds overall.