Under ice spills of conventional crude oil and diluted bitumen: Physiological resilience of the blue mussel and transgenerational effects.

Spillages at sea of diluted bitumen (dilbit) from oil sands have received little attention until now. To our best knowledge, there are no reports on the impact of a severe exposure to dilbit on the Blue mussel (Mytilus edulis). In this study, adult Blue mussels were exposed to one conventional crude oil (Heidrun) and two dilbits (Cold Lake Blend and Access Western Blend) for a period of 7 days in an ice-covered environment and then maintained for three months until the spawning season. The exposed mussels were monitored for aromatic hydrocarbon bioaccumulation, physiological energetic budget, cellular stress, byssus production and gametogenesis. In spring, spawning was induced to characterize breeding success. Bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) was detected after three days of exposure, with higher concentrations of PAHs associated to the conventional oil (5.49 ± 0.12 µg·g-1 d.w.) compared to both dilbits (0.91 ± 0.02 µg·g-1; 0.51 ± 0.03 µg·g-1 d.w.). Despite a fast depuration rate and a good resilience of the exposed mussels, significant negative effects were observed at the cellular, physiological and fitness levels, especially in offspring. Our results suggest a higher toxicity of the diluted bitumen compared to the conventional crude despite the lower bioaccumulation of total PAHs. Dilbit treatments caused evident negative transgenerational effects on unexposed F1 generation.

Auditory brainstem response asymmetries in older adults: An exploratory study using click and speech stimuli.

BACKGROUND: Some evidence suggests that young adults exhibit a selective laterality of auditory brainstem response (ABR) elicited with speech stimuli. Little is known about such an auditory laterality in older adults. OBJECTIVE: The aim of this study was to investigate possible asymmetric auditory brainstem processing between right and left ear presentation in older adults. METHODS: Sixty-two older adults presenting with normal hearing thresholds according to their age and who were native speakers of Quebec French participated in this study. ABR was recorded using click and a 40-ms /da/ syllable. ABR was elicited through monaural right and monaural left stimulation. Latency and amplitude for click-and speech-ABR components were compared between right and left ear presentations. In addition, for the /da/ syllable, a fast Fourier transform analysis of the sustained frequency-following response (FFR) of the vowel was performed along with stimulus-to-response and right-left ear correlation analyses. RESULTS: No significant differences between right and left ear presentation were found for amplitudes and latencies of the click-ABR components. Significantly shorter latencies for right ear presentation as compared to left ear presentation were observed for onset and offset transient components (V, A and O), sustained components (D and E), and voiced transition components (C) of the speech-ABR. In addition, the spectral amplitude of the fundamental frequency (F0) was significantly larger for the left ear presentation than the right ear presentation. CONCLUSIONS: Results of this study show that older adults with normal hearing exhibit symmetric encoding for click stimuli at the brainstem level between the right and left ear presentation. However, they present with brainstem asymmetries for the encoding of selective stimulus components of the speech-ABR between the right and left ear presentation. The right ear presentation of a /da/ syllable elicited reduced neural timing for both transient and sustained components compared to the left ear. Conversely, a stronger left ear F0 encoding was observed. These findings suggest that at a preattentive, sensory stage of auditory processing, older adults lateralize speech stimuli similarly to young adults.

Changing the narrative for hearing health in the broader context of healthy living: a call to action.

OBJECTIVE: To discuss the steps necessary to facilitate hearing health care in the context of well-being and healthy living. DESIGN: Common themes among the articles in this special supplement of the International Journal of Audiology were used to identify issues that must be addressed if audiology is to move from being hearing-focussed to taking a holistic perspective of hearing care in the context of healthy aging. These are discussed within the context of other published literature. RESULTS AND CONCLUSIONS: Three needs were identified: (i) Increased interdisciplinary education to raise awareness of the interplay between hearing and health. (ii) Increased emphasis on counselling education in audiology programs so that audiologists are equipped with the knowledge, competence and confidence to provide counselling and emotional support to their patients, beyond care. (iii) Redefinition of therapeutic goal setting and hearing outcomes to include aspects of well-being, so that audiologists can capture and patients realise that that good hearing outcomes can have a direct positive impact on a person's quality of life that extends beyond their improved ability to hear. It was emphasised that each of these needs to be considered within the context of the audiologists' scope of practice and audiologists' well-being.

Behavioral Assessment of Listening Effort Using a Dual-Task Paradigm.

Published investigations ( n = 29) in which a dual-task experimental paradigm was employed to measure listening effort during speech understanding in younger and older adults were reviewed. A summary of the main findings reported in the articles is provided with respect to the participants' age-group and hearing status. Effects of different signal characteristics, such as the test modality, on dual-task outcomes are evaluated, and associations with cognitive abilities and self-report measures of listening effort are described. Then, several procedural issues associated with the use of dual-task experiment paradigms are discussed. Finally, some issues that warrant future research are addressed. The review revealed large variability in the dual-task experimental paradigms that have been used to measure the listening effort expended during speech understanding. The differences in experimental procedures used across studies make it difficult to draw firm conclusions concerning the optimal choice of dual-task paradigm or the sensitivity of specific paradigms to different types of experimental manipulations. In general, the analysis confirmed that dual-task paradigms have been used successfully to measure differences in effort under different experimental conditions, in both younger and older adults. Several research questions that warrant further investigation in order to better understand and characterize the intricacies of dual-task paradigms were identified.

International Collegium of Rehabilitative Audiology (ICRA) recommendations for the construction of multilingual speech tests. ICRA Working Group on Multilingual Speech Tests.

OBJECTIVE: To provide guidelines for the development of two types of closed-set speech-perception tests that can be applied and interpreted in the same way across languages. The guidelines cover the digit triplet and the matrix sentence tests that are most commonly used to test speech recognition in noise. They were developed by a working group on Multilingual Speech Tests of the International Collegium of Rehabilitative Audiology (ICRA). DESIGN: The recommendations are based on reviews of existing evaluations of the digit triplet and matrix tests as well as on the research experience of members of the ICRA Working Group. They represent the results of a consensus process. RESULTS: The resulting recommendations deal with: Test design and word selection; Talker characteristics; Audio recording and stimulus preparation; Masking noise; Test administration; and Test validation. CONCLUSIONS: By following these guidelines for the development of any new test of this kind, clinicians and researchers working in any language will be able to perform tests whose results can be compared and combined in cross-language studies.

Audiovisual segregation in cochlear implant users.

It has traditionally been assumed that cochlear implant users de facto perform atypically in audiovisual tasks. However, a recent study that combined an auditory task with visual distractors suggests that only those cochlear implant users that are not proficient at recognizing speech sounds might show abnormal audiovisual interactions. The present study aims at reinforcing this notion by investigating the audiovisual segregation abilities of cochlear implant users in a visual task with auditory distractors. Speechreading was assessed in two groups of cochlear implant users (proficient and non-proficient at sound recognition), as well as in normal controls. A visual speech recognition task (i.e. speechreading) was administered either in silence or in combination with three types of auditory distractors: i) noise ii) reverse speech sound and iii) non-altered speech sound. Cochlear implant users proficient at speech recognition performed like normal controls in all conditions, whereas non-proficient users showed significantly different audiovisual segregation patterns in both speech conditions. These results confirm that normal-like audiovisual segregation is possible in highly skilled cochlear implant users and, consequently, that proficient and non-proficient CI users cannot be lumped into a single group. This important feature must be taken into account in further studies of audiovisual interactions in cochlear implant users.

Older adults expend more listening effort than young adults recognizing audiovisual speech in noise.

OBJECTIVE: Using a dual task paradigm, two experiments were conducted to: (1) quantify the listening effort that young and older adults expend to recognize speech in noise when presented under audio-only (Experiment 1) and audiovisual conditions (Experiment 2) and, (2) determine the influence visual cues have on listening effort. Listening effort refers to the attentional and cognitive resources required to understand speech. DESIGN: All participants performed a closed-set word recognition task and tactile pattern recognition task separately and concurrently. Accuracy and reaction time data were collected. The criterion for single task word recognition performance was set to 80% correct across experiments and across age groups. STUDY SAMPLE: For each experiment, 25 young and 25 older adults with normal hearing and normal (or corrected normal) vision participated. RESULTS: Under equated performance conditions, older adults expended more listening effort than young adults with both audio-only and audiovisually presented speech. Furthermore, the processing demands of audiovisual speech recognition were greater than audio-only speech recognition for all participants. CONCLUSIONS: These results suggest that while visual cues can improve audiovisual speech recognition, they can also place an extra demand on processing resources with performance consequences for the word and tactile tasks under dual task conditions.

Speech perception in noise: exploring the effect of linguistic context in children with and without auditory processing disorder.

OBJECTIVE: The objective of this study was to investigate whether the speech perception problems in noise of children with auditory processing disorder (APD) stem from an auditory or a higher order dysfunction. DESIGN: A repeated measures design comparing the sentence key word recognition scores of children with APD and a control group was used. Four sentence lists from the Test de phrases dans le bruit (TPB) were presented with a babble masker at four different signal-to-noise ratios. The TPB is a Canadian French adaptation of the speech perception in noise test. STUDY SAMPLE: Ten participants between 9-12 years with APD participated in this study, as well as ten age- and gender-matched children with no sign of APD. RESULTS: Group analyses revealed that children with APD had poorer overall sentence key word recognition scores than the control group. Analysis of the difference scores between the high and low predictability sentences indicated that the benefit derived from linguistic context is similar between the groups. However, individual patterns of results revealed different profiles within the APD group. CONCLUSION: Further study using a larger sample is warranted to deepen our understanding of the nature of APD and identify characteristic profiles to enable better tailoring of therapeutic programs.

The effects of blurred vision on auditory-visual speech perception in younger and older adults.

Speech understanding is improved when the observer can both see and hear the talker. This study compared the effects of reduced visual acuity on auditory-visual (AV) speech-recognition in noise among younger and older adults. Two groups of participants performed a closed-set sentence-recognition task in one auditory-alone (A-alone) condition and under three AV conditions: normal visual acuity (6/6), and with blurred vision to simulate a 6/30 and 6/60 visual impairment. The results showed that (1) the addition of visual speech cues improved speech-perception relative to the A-alone condition, (2) under the AV conditions, performance declined as the amount of blurring increased, (3) even under the AV condition that simulated a visual acuity of 6/60, the speech recognition scores were significantly higher than those obtained under the A-alone condition, and (4) generally, younger adults obtained higher scores than older adults under all conditions. Our results demonstrate the benefits of visual cues to enhance speech understanding even when visual acuity is not optimal.

Auditory processing disorder and speech perception problems in noise: finding the underlying origin.

PURPOSE: A hallmark listening problem of individuals presenting with auditory processing disorder (APD) is their poor recognition of speech in noise. The underlying perceptual problem of the listening difficulties in unfavorable listening conditions is unknown. The objective of this article was to demonstrate theoretically how to determine whether the speech recognition problems are related to an auditory dysfunction, a language-based dysfunction, or a combination of both. METHOD: Tests such as the Speech Perception in Noise (SPIN) test allow the exploration of the auditory and language-based functions involved in speech perception in noise, which is not possible with most other speech-in-noise tests. Psychometric functions illustrating results from hypothetical groups of individuals with APD on the SPIN test are presented. This approach makes it possible to postulate about the origin of the speech perception problems in noise. CONCLUSION: APD is a complex and heterogeneous disorder for which the underlying deficit is currently unclear. Because of their design, SPIN-like tests can potentially be used to identify the nature of the deficits underlying problems with speech perception in noise for this population. A better understanding of the difficulties with speech perception in noise experienced by many listeners with APD should lead to more efficient intervention programs.

Evaluating the effort expended to understand speech in noise using a dual-task paradigm: the effects of providing visual speech cues.

PURPOSE: Using a dual-task paradigm, 2 experiments (Experiments 1 and 2) were conducted to assess differences in the amount of listening effort expended to understand speech in noise in audiovisual (AV) and audio-only (A-only) modalities. Experiment 1 had equivalent noise levels in both modalities, and Experiment 2 equated speech recognition performance levels by increasing the noise in the AV versus A-only modality. METHOD: Sixty adults were randomly assigned to Experiment 1 or Experiment 2. Participants performed speech and tactile recognition tasks separately (single task) and concurrently (dual task). The speech tasks were performed in both modalities. Accuracy and reaction time data were collected as well as ratings of perceived accuracy and effort. RESULTS: In Experiment 1, the AV modality speech recognition was rated as less effortful, and accuracy scores were higher than A only. In Experiment 2, reaction times were slower, tactile task performance was poorer, and listening effort increased, in the AV versus the A-only modality. CONCLUSIONS: At equivalent noise levels, speech recognition performance was enhanced and subjectively less effortful in the AV than A-only modality. At equivalent accuracy levels, the dual-task performance decrements (for both tasks) suggest that the noisier AV modality was more effortful than the A-only modality.

Auditory pathways fail to re-establish normal cortical activation patterns in response to binaural stimulation following a unilateral lesion of the inferior colliculus.

The aim of this study was to investigate cortical activation in response to binaural stimulus presentations in an individual (FX) with a circumscribed traumatic hemorrhagic lesion of the right inferior colliculus. FX and control subjects were exposed to complex sounds while undergoing a functional magnetic resonance imaging assessment. Whereas normally-hearing individuals show well-balanced bilateral activation patterns in response to binaural auditory stimulation, the same stimuli produced stronger activation in the left hemisphere in FX. Combined with previous data, these findings reinforce the notion that the inferior colliculus is an essential auditory relay and that its loss cannot be significantly compensated.

Visual stimuli can impair auditory processing in cochlear implant users.

It has been shown that visual stimulation can activate cortical regions normally devoted to auditory processing in deaf individuals. This neural activity can persist even when audition is restored through the implantation of a cochlear implant, raising the possibility that cross-modal plasticity can be detrimental to auditory performance in cochlear implant users. To determine the influence of visual information on auditory performance after restoration of hearing in deaf individuals, the ability to segregate conflicting auditory and visual information was assessed in fourteen cochlear implant users with varied degree of expertise and an equal number of participants with normal-hearing matched for gender, age and hearing performance. An auditory speech recognition task was administered in the presence of three incongruent visual stimuli (color-shift, random-dot motion and lip movement). For proficient cochlear implant users, auditory performance was equal to that of controls in the three experimental conditions where visual stimuli were presented simultaneously with auditory information. For non-proficient cochlear implant users, performance did not differ from that of matched controls when the auditory stimulus was paired with a visual stimulus that was color-shifted. However, significant differences were observed between the non-proficient cochlear implant users and their matched controls when the accompanying visual stimuli consisted of a moving random-dot pattern or incongruent lip movements. These findings raise several questions with regards to the rehabilitation of cochlear implant users.

Auditory scene analysis following unilateral inferior colliculus infarct.

Event-related potentials in the form of mismatch negativity were recorded to investigate auditory scene analysis capabilities in a person with a very circumscribed haemorrhagic lesion at the level of the right inferior colliculus. The results provide the first objective evidence that processing at the level of the inferior colliculus plays an important role in human auditory frequency discrimination. Moreover, the electrophysiological data suggest that following this unilateral lesion, the auditory pathways fail to reorganize efficiently.

A role for the inferior colliculus in multisensory speech integration.

Multisensory integration can occur at relatively low levels within the central nervous system. Recent evidence suggests that multisensory audio-visual integration for speech may have a subcortical component, as acoustic processing in the human brainstem is influenced by lipreading during speech perception. Here, stimuli depicting the McGurk illusion (a demonstration of auditory-visual integration using speech stimuli) were presented to a 12-year-old child (FX) with a circumscribed unilateral lesion of the right inferior colliculus. When McGurk-type stimuli were presented in the contralesional hemifield, illusory perception reflecting bimodal integration was significantly reduced compared with the ipsilesional hemifield and a group of age-matched controls. These data suggest a functional role for the inferior colliculus in the audio-visual integration of speech stimuli.