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

Simulation of visual impairment in persons with normal vision for scientific research

Simulation of visual impairment in healthy eyes has multiple applications in students' training, research and product development. However, due to the absence of an existing standard protocol, the method of simulation was left to the discretion of the researcher. This review aimed to outline the various methods of simulating visual impairment and categorising them. A scoping review of the relevant publications was conducted. Of the 1593 articles originally retrieved from the databases, 103 were included in the review. The characteristics of the participants, the method for simulation of the visual impairment in persons with normal vision and the level or type of visual impairment that was simulated were extracted from the papers. None of the methods of simulation can be judged as being superior to the others. However, electronic displays produced the most consistent form of visual impairment simulation.

Plain-to-clear speech video conversion for enhanced intelligibility

Clearly articulated speech, relative to plain-style speech, has been shown to improve intelligibility. We examine if visible speech cues in video only can be systematically modified to enhance clear-speech visual features and improve intelligibility. We extract clear-speech visual features of English words varying in vowels produced by multiple male and female talkers. Via a frame-by-frame image-warping based video generation method with a controllable parameter (displacement factor), we apply the extracted clear-speech visual features to videos of plain speech to synthesize clear speech videos. We evaluate the generated videos using a robust, state of the art AI Lip Reader as well as human intelligibility testing. The contributions of this study are: (1) we successfully extract relevant visual cues for video modifications across speech styles, and have achieved enhanced intelligibility for AI; (2) this work suggests that universal talker-independent clear-speech features may be utilized to modify any talker's visual speech style; (3) we introduce "displacement factor" as a way of systematically scaling the magnitude of displacement modifications between speech styles; and (4) the high definition generated videos make them ideal candidates for human-centric intelligibility and perceptual training studies.

Benefits of Text Supplementation on Sentence Recognition and Subjective Ratings With and Without Facial Cues for Listeners With Normal Hearing

OBJECTIVES

Recognizing speech through telecommunication can be challenging in unfavorable listening conditions. Text supplementation or provision of facial cues can facilitate speech recognition under some circumstances. However, our understanding of the combined benefit of text and facial cues in telecommunication is limited. The purpose of this study was to investigate the potential benefit of text supplementation for sentence recognition scores and subjective ratings of spoken speech with and without facial cues available.

DESIGN

Twenty adult females (M = 24 years, range 21 to 29 years) with normal hearing performed a sentence recognition task and also completed a subjective rating questionnaire in 24 conditions. The conditions varied by integrity of the available facial cues (clear facial cues, slight distortion facial cues, great distortion facial cues, no facial cues), signal-to-noise ratio (quiet, +1 dB, -3 dB), and text availability (with text, without text). When present, the text was an 86 to 88% accurate transcription of the auditory signal presented at a 500 ms delay relative to the auditory signal.

RESULTS

The benefits of text supplementation were largest when facial cues were not available and when the signal-to-noise ratio was unfavorable. Although no recognition score benefit was present in quiet, recognition benefit was significant in all levels of background noise for all levels of facial cue integrity. Moreover, participant subjective ratings of text benefit were robust and present even in the absence of recognition benefit. Consistent with previous literature, facial cues were beneficial for sentence recognition scores in the most unfavorable signal-to-noise ratio, even when greatly distorted. It is interesting that, although all levels of facial cues were beneficial for recognition scores, participants rated a significant benefit only with clear facial cues.

CONCLUSIONS

The benefit of text for auditory-only and auditory-visual speech recognition is evident in recognition scores and subjective ratings; the benefit is larger and more robust for subjective ratings than for scores. Therefore, text supplementation might provide benefit that extends beyond speech recognition scores. Combined, these findings support the use of text supplementation in telecommunication, even when facial cues are concurrently present, such as during teleconferencing or watching television.

A Scoping Review of Audiovisual Integration Methodology: Screening for Auditory and Visual Impairment in Younger and Older Adults

With the rise of the aging population, many scientists studying multisensory integration have turned toward understanding how this process may change with age. This scoping review was conducted to understand and describe the scope and rigor with which researchers studying audiovisual sensory integration screen for hearing and vision impairment. A structured search in three licensed databases (Scopus, PubMed, and PsychInfo) using the key concepts of multisensory integration, audiovisual modality, and aging revealed 2,462 articles, which were screened for inclusion by two reviewers. Articles were included if they (1) tested healthy older adults (minimum mean or median age of 60) with younger adults as a comparison (mean or median age between 18 and 35), (2) measured auditory and visual integration, (3) were written in English, and (4) reported behavioral outcomes. Articles that included the following were excluded: (1) tested taste exclusively, (2) tested olfaction exclusively, (3) tested somatosensation exclusively, (4) tested emotion perception, (5) were not written in English, (6) were clinical commentaries, editorials, interviews, letters, newspaper articles, abstracts only, or non-peer reviewed literature (e.g., theses), and (7) focused on neuroimaging without a behavioral component. Data pertaining to the details of the study (e.g., country of publication, year of publication, etc.) were extracted, however, of higher importance to our research question, data pertaining to screening measures used for hearing and vision impairment (e.g., type of test used, whether hearing- and visual-aids were worn, thresholds used, etc.) were extracted, collated, and summarized. Our search revealed that only 64% of studies screened for age-abnormal hearing impairment, 51% screened for age-abnormal vision impairment, and that consistent definitions of normal or abnormal vision and hearing were not used among the studies that screened for sensory abilities. A total of 1,624 younger adults and 4,778 older participants were included in the scoping review with males composing approximately 44% and females composing 56% of the total sample and most of the data was obtained from only four countries. We recommend that studies investigating the effects of aging on multisensory integration should screen for normal vision and hearing by using the World Health Organization's (WHO) hearing loss and visual impairment cut-off scores in order to maintain consistency among other aging researchers. As mild cognitive impairment (MCI) has been defined as a “transitional” or a “transitory” stage between normal aging and dementia and because approximately 3–5% of the aging population will develop MCI each year, it is therefore important that when researchers aim to study a healthy aging population, that they appropriately screen for MCI. One of our secondary aims was to determine how often researchers were screening for cognitive impairment and the types of tests that were used to do so. Our results revealed that only 55 out of 72 studies tested for neurological and cognitive function, and only a subset used standardized tests. Additionally, among the studies that used standardized tests, the cut-off scores used were not always adequate for screening out mild cognitive impairment. An additional secondary aim of this scoping review was to determine the feasibility of whether a meta-analysis could be conducted in the future to further quantitatively evaluate the results (i.e., are the findings obtained from studies using self-reported vision and hearing impairment screening methods significantly different from those measuring vision and hearing impairment in the lab) and to assess the scope of this problem. We found that it may not be feasible to conduct a meta-analysis with the entire dataset of this scoping review. However, a meta-analysis can be conducted if stricter parameters are used (e.g., focusing on accuracy or response time data only).

Systematic Review Registration:https://doi.org/10.17605/OSF.IO/GTUHD.

[Hearing care aspects in universal face mask use during the COVID 19 pandemic]

BACKGROUND

Typical cloth and medical masks, which are mandatory to wear during the COVID 19 pandemic, create visual barrier, obscure linguistic and nonverbal communication and interaction. Ski-slope hearing loss patients often don't admit their auditory insufficiency and do not use hearing aids due to acceptable speech intelligibility by using visual access to the mouth and other potential facial cues.

PURPOSE

To assess the impact of universal face medical masks in public places on motivation to using hearing aids of patients with ski-slope hearing loss.

PATIENTS AND METHODS

All the 504 patients (18-65 years old), who applied for < hearing care assistance and for the first time bought hearing aid were included. 266 patients (group A) applied from June to November 2020, when wearing facial masks was mandatory; 238 patients (group B) applied from June to November 2019, when wearing facial masks wasn't required. In both groups patients, who fulfilled the following criteria, were selected: 1) binaural mild to severe sensorineural ski-slope hearing loss lasting more than 3 years; 2) no progression of hearing loss within the last 3 years; 3) pure tone audiometry <20 dB HL at 125-1000 Hz frequencies; 4) hearing care with mono- or binaural hearing aids with the receiver-in-the-canal open-type. Questionnaires were administered to eligible patients in group A to assess the motivational components of acquiring hearing aids.

RESULTS AND DISCUSSION

In group A, 74 (28%) patients received hearing aids according to the inclusion criteria, and in group B, 46 (19%) patients received hearing aids (p=0.033). Significant factors determining hearing aid acquisition were lack of visual contact when wearing a mask, communication difficulties in noisy environments and lack of intelligibility in a concert hall or lecture.

CONCLUSION

Patients' motivation to hearing care grows in mandatory wearing facial masks conditions during the COVID-19 pandemic leading to an increase in patients using hearing aids.

Recognition of Accented Speech by Cochlear-Implant Listeners: Benefit of Audiovisual Cues

OBJECTIVES

When auditory and visual speech information are presented together, listeners obtain an audiovisual (AV) benefit or a speech understanding improvement compared with auditory-only (AO) or visual-only (VO) presentations. Cochlear-implant (CI) listeners, who receive degraded speech input and therefore understand speech using primarily temporal information, seem to readily use visual cues and can achieve a larger AV benefit than normal-hearing (NH) listeners. It is unclear, however, if the AV benefit remains relatively large for CI listeners when trying to understand foreign-accented speech when compared with unaccented speech. Accented speech can introduce changes to temporal auditory cues and visual cues, which could decrease the usefulness of AV information. Furthermore, we sought to determine if the AV benefit was relatively larger in CI compared with NH listeners for both unaccented and accented speech.

DESIGN

AV benefit was investigated for unaccented and Spanish-accented speech by presenting English sentences in AO, VO, and AV conditions to 15 CI and 15 age- and performance-matched NH listeners. Performance matching between NH and CI listeners was achieved by varying the number of channels of a noise vocoder for the NH listeners. Because of the differences in age and hearing history of the CI listeners, the effects of listener-related variables on speech understanding performance and AV benefit were also examined.

RESULTS

AV benefit was observed for both unaccented and accented conditions and for both CI and NH listeners. The two groups showed similar performance for the AO and AV conditions, and the normalized AV benefit was relatively smaller for the accented than the unaccented conditions. In the CI listeners, older age was associated with significantly poorer performance with the accented speaker compared with the unaccented speaker. The negative impact of age was somewhat reduced by a significant improvement in performance with access to AV information.

CONCLUSIONS

When auditory speech information is degraded by CI sound processing, visual cues can be used to improve speech understanding, even in the presence of a Spanish accent. The AV benefit of the CI listeners closely matched that of the NH listeners presented with vocoded speech, which was unexpected given that CI listeners appear to rely more on visual information to communicate. This result is perhaps due to the one-to-one age and performance matching of the listeners. While aging decreased CI listener performance with the accented speaker, access to visual cues boosted performance and could partially overcome the age-related speech understanding deficits for the older CI listeners.

Living with deafblindness during COVID-19: An international webinar to facilitate global knowledge translation

Arguably, individuals living with deafblindness are among the hardest hit by the effects of the corona virus disease of 2019 (COVID- 19), given the importance of the sense of touch for their ability to interact with the world. To address this challenge, it is imperative to facilitate the implementation of evidence- and experience-based recommendations, and to improve knowledge translation on a global scale. Deafblind International organized a webinar to provide a platform where participants could exchange experiences and solutions to overcome the challenges created by the arrival of COVID-19, in order to facilitate information exchange among stakeholders in deafblindness during this pandemic. We present an overview of its content here and place the summarized themes in context with existing research literature. Abstract submission was open for 4 weeks in May 2020, resulting in 30 submissions from 13 countries across 5 continents. Of the 26 presenter teams, 9 (35%) had a co-presenter that was living with deafblindness themselves. The number of individual participants across all sessions ranged from 55 to 140 ( M = 98), with a total of 3709 session registrations overall, and the organizers estimate a total attendance of around 400 participants. Based on extensive field notes taken during the webinar, and repeated viewing of the recordings, qualitative description allowed the team to synthesize eight principal themes across the event: access to information, communication, service accessibility, adaptations to service delivery, online safety and security, physical distancing, mental health and research. The first Deafblind International webinar was able to fill an important gap by bringing together a variety of stakeholders in deafblindness across the globe. The event created a sense of group membership and peer support, brought the participants, researchers, the professionals as well as their service agencies closer together and generated a sense of hope and collaboration.

Ageing and multisensory integration: A review of the evidence, and a computational perspective

The processing of multisensory signals is crucial for effective interaction with the environment, but our ability to perform this vital function changes as we age. In the first part of this review, we summarise existing research into the effects of healthy ageing on multisensory integration. We note that age differences vary substantially with the paradigms and stimuli used: older adults often receive at least as much benefit (to both accuracy and response times) as younger controls from congruent multisensory stimuli, but are also consistently more negatively impacted by the presence of intersensory conflict. In the second part, we outline a normative Bayesian framework that provides a principled and computationally informed perspective on the key ingredients involved in multisensory perception, and how these are affected by ageing. Applying this framework to the existing literature, we conclude that changes to sensory reliability, prior expectations (together with attentional control), and decisional strategies all contribute to the age differences observed. However, we find no compelling evidence of any age-related changes to the basic inference mechanisms involved in multisensory perception.

Short-term effects of sound localization training in virtual reality

Head-related transfer functions (HRTFs) capture the direction-dependant way that sound interacts with the head and torso. In virtual audio systems, which aim to emulate these effects, non-individualized, generic HRTFs are typically used leading to an inaccurate perception of virtual sound location. Training has the potential to exploit the brain's ability to adapt to these unfamiliar cues. In this study, three virtual sound localization training paradigms were evaluated; one provided simple visual positional confirmation of sound source location, a second introduced game design elements ("gamification") and a final version additionally utilized head-tracking to provide listeners with experience of relative sound source motion ("active listening"). The results demonstrate a significant effect of training after a small number of short (12-minute) training sessions, which is retained across multiple days. Gamification alone had no significant effect on the efficacy of the training, but active listening resulted in a significantly greater improvements in localization accuracy. In general, improvements in virtual sound localization following training generalized to a second set of non-individualized HRTFs, although some HRTF-specific changes were observed in polar angle judgement for the active listening group. The implications of this on the putative mechanisms of the adaptation process are discussed.

Psychobiological Responses Reveal Audiovisual Noise Differentially Challenges Speech Recognition

OBJECTIVES

In noisy environments, listeners benefit from both hearing and seeing a talker, demonstrating audiovisual (AV) cues enhance speech-in-noise (SIN) recognition. Here, we examined the relative contribution of auditory and visual cues to SIN perception and the strategies used by listeners to decipher speech in noise interference(s).

DESIGN

Normal-hearing listeners (n = 22) performed an open-set speech recognition task while viewing audiovisual TIMIT sentences presented under different combinations of signal degradation including visual (AVn), audio (AnV), or multimodal (AnVn) noise. Acoustic and visual noises were matched in physical signal-to-noise ratio. Eyetracking monitored participants' gaze to different parts of a talker's face during SIN perception.

RESULTS

As expected, behavioral performance for clean sentence recognition was better for A-only and AV compared to V-only speech. Similarly, with noise in the auditory channel (AnV and AnVn speech), performance was aided by the addition of visual cues of the talker regardless of whether the visual channel contained noise, confirming a multimodal benefit to SIN recognition. The addition of visual noise (AVn) obscuring the talker's face had little effect on speech recognition by itself. Listeners' eye gaze fixations were biased toward the eyes (decreased at the mouth) whenever the auditory channel was compromised. Fixating on the eyes was negatively associated with SIN recognition performance. Eye gazes on the mouth versus eyes of the face also depended on the gender of the talker.

CONCLUSIONS

Collectively, results suggest listeners (1) depend heavily on the auditory over visual channel when seeing and hearing speech and (2) alter their visual strategy from viewing the mouth to viewing the eyes of a talker with signal degradations, which negatively affects speech perception.

CAPTCHA as a Visual Performance Metric in Active Macular Disease

Purpose

CAPTCHA (completely automated public turing test to tell computers and humans apart) was designed as a spam prevention test. In patients with visual impairment, completion of this task has been assumed to be difficult; but to date, no study has proven this to be true. As visual function is not well measured by Snellen visual acuity (VA) alone, we theorized that CAPTCHA performance may provide additional information on macular disease-related visual dysfunction.

Methods

This was designed as a pilot study. Active disease was defined as the presence of either intraretinal fluid (IRF) or subretinal fluid (SRF) on spectral-domain optical coherence tomography. CAPTCHA performance was tested using 10 prompts. In addition, near and distance VA, contrast sensitivity, and reading speed were measured. Visual acuity matched pseudophakic patients were used as controls. Primary outcome measures were average edit distance and percent of correct responses.

Results

70 patients were recruited: 33 with active macular disease and 37 control subjects. Contrast sensitivity was found to be significantly different in both the IRF (p < 0.01) and SRF groups (p < 0.01). No significant difference was found comparing the odds ratio of average edit distance of active disease (IRF, SRF) vs. control (OR 1.09 (0.62, 1.90), 1.10 (0.58, 2.05), p=0.77,  0.77) or percent correct responses of active disease vs. control (OR 0.98 (0.96, 1.01), 1.09 (0.58, 2.05), p=0.22, 0.51) in CAPTCHA testing. The goodness of fit using logistic regression analysis for the dependent variables of either IRF or SRF did not improve accounting for average edit distance (p=0.49,  p=0.27) or percent correct (p=0.89,  p=0.61).

Conclusions

Distance VA and contrast sensitivity are positively correlated with the presence of IRF and SRF in active macular disease. CAPTCHA performance did not appear to be a significant predictor of either IRF or SRF in our pilot study.

Audiovisual Temporal Perception in Aging: The Role of Multisensory Integration and Age-Related Sensory Loss

Within each sensory modality, age-related deficits in temporal perception contribute to the difficulties older adults experience when performing everyday tasks. Since perceptual experience is inherently multisensory, older adults also face the added challenge of appropriately integrating or segregating the auditory and visual cues present in our dynamic environment into coherent representations of distinct objects. As such, many studies have investigated how older adults perform when integrating temporal information across audition and vision. This review covers both direct judgments about temporal information (the sound-induced flash illusion, temporal order, perceived synchrony, and temporal rate discrimination) and judgments regarding stimuli containing temporal information (the audiovisual bounce effect and speech perception). Although an age-related increase in integration has been demonstrated on a variety of tasks, research specifically investigating the ability of older adults to integrate temporal auditory and visual cues has produced disparate results. In this short review, we explore what factors could underlie these divergent findings. We conclude that both task-specific differences and age-related sensory loss play a role in the reported disparity in age-related effects on the integration of auditory and visual temporal information.

Shifts in Maximum Audiovisual Integration with Age

Listeners attempting to understand speech in noisy environments rely on visual and auditory processes, typically referred to as audiovisual processing. Noise corrupts the auditory speech signal and listeners naturally leverage visual cues from the talker’s face in an attempt to interpret the degraded auditory signal. Studies of speech intelligibility in noise show that the maximum improvement in speech recognition performance (i.e., maximum visual enhancement or VEmax), derived from seeing an interlocutor’s face, is invariant with age. Several studies have reported that VEmaxis typically associated with a signal-to-noise (SNR) of −12 dB; however, few studies have systematically investigated whether the SNR associated with VEmaxchanges with age. We investigated if VEmaxchanges as a function of age, whether the SNR at VEmaxchanges as a function of age, and what perceptual/cognitive abilities account for or mediate such relationships. We measured VEmaxon a nongeriatric adult sample () ranging in age from 20 to 59 years old. We found that VEmaxwas age-invariant, replicating earlier studies. No perceptual/cognitive measures predicted VEmax, most likely due to limited variance in VEmaxscores. Importantly, we found that the SNR at VEmaxshifts toward higher (quieter) SNR levels with increasing age; however, this relationship is partially mediated by working memory capacity, where those with larger working memory capacities (WMCs) can identify speech under lower (louder) SNR levels than their age equivalents with smaller WMCs. The current study is the first to report that individual differences in WMC partially mediate the age-related shift in SNR at VEmax.

Spatial Hearing with Incongruent Visual or Auditory Room Cues

In day-to-day life, humans usually perceive the location of sound sources as outside their heads. This externalized auditory spatial perception can be reproduced through headphones by recreating the sound pressure generated by the source at the listener’s eardrums. This requires the acoustical features of the recording environment and listener’s anatomy to be recorded at the listener’s ear canals. Although the resulting auditory images can be indistinguishable from real-world sources, their externalization may be less robust when the playback and recording environments differ. Here we tested whether a mismatch between playback and recording room reduces perceived distance, azimuthal direction, and compactness of the auditory image, and whether this is mostly due to incongruent auditory cues or to expectations generated from the visual impression of the room. Perceived distance ratings decreased significantly when collected in a more reverberant environment than the recording room, whereas azimuthal direction and compactness remained room independent. Moreover, modifying visual room-related cues had no effect on these three attributes, while incongruent auditory room-related cues between the recording and playback room did affect distance perception. Consequently, the external perception of virtual sounds depends on the degree of congruency between the acoustical features of the environment and the stimuli.

Spatial Frequency Requirements and Gaze Strategy in Visual-Only and Audiovisual Speech Perception

PURPOSE

The aim of this article is to examine the effects of visual image degradation on performance and gaze behavior in audiovisual and visual-only speech perception tasks.

METHOD

We presented vowel-consonant-vowel utterances visually filtered at a range of frequencies in visual-only, audiovisual congruent, and audiovisual incongruent conditions (Experiment 1; N = 66). In Experiment 2 (N = 20), participants performed a visual-only speech perception task and in Experiment 3 (N = 20) an audiovisual task while having their gaze behavior monitored using eye-tracking equipment.

RESULTS

In the visual-only condition, increasing image resolution led to monotonic increases in performance, and proficient speechreaders were more affected by the removal of high spatial information than were poor speechreaders. The McGurk effect also increased with increasing visual resolution, although it was less affected by the removal of high-frequency information. Observers tended to fixate on the mouth more in visual-only perception, but gaze toward the mouth did not correlate with accuracy of silent speechreading or the magnitude of the McGurk effect.

CONCLUSIONS

The results suggest that individual differences in silent speechreading and the McGurk effect are not related. This conclusion is supported by differential influences of high-resolution visual information on the 2 tasks and differences in the pattern of gaze.

Lipreading and audiovisual speech recognition across the adult lifespan: Implications for audiovisual integration

In this study of visual (V-only) and audiovisual (AV) speech recognition in adults aged 22-92 years, the rate of age-related decrease in V-only performance was more than twice that in AV performance. Both auditory-only (A-only) and V-only performance were significant predictors of AV speech recognition, but age did not account for additional (unique) variance. Blurring the visual speech signal decreased speech recognition, and in AV conditions involving stimuli associated with equivalent unimodal performance for each participant, speech recognition remained constant from 22 to 92 years of age. Finally, principal components analysis revealed separate visual and auditory factors, but no evidence of an AV integration factor. Taken together, these results suggest that the benefit that comes from being able to see as well as hear a talker remains constant throughout adulthood and that changes in this AV advantage are entirely driven by age-related changes in unimodal visual and auditory speech recognition. (PsycINFO Database Record

Effects of aging on audio-visual speech integration

This study investigated the impact of aging on audio-visual speech integration. A syllable identification task was presented in auditory-only, visual-only, and audio-visual congruent and incongruent conditions. Visual cues were either degraded or unmodified. Stimuli were embedded in stationary noise alternating with modulated noise. Fifteen young adults and 15 older adults participated in this study. Results showed that older adults had preserved lipreading abilities when the visual input was clear but not when it was degraded. The impact of aging on audio-visual integration also depended on the quality of the visual cues. In the visual clear condition, the audio-visual gain was similar in both groups and analyses in the framework of the fuzzy-logical model of perception confirmed that older adults did not differ from younger adults in their audio-visual integration abilities. In the visual reduction condition, the audio-visual gain was reduced in the older group, but only when the noise was stationary, suggesting that older participants could compensate for the loss of lipreading abilities by using the auditory information available in the valleys of the noise. The fuzzy-logical model of perception confirmed the significant impact of aging on audio-visual integration by showing an increased weight of audition in the older group.

Dual sensory loss: development of a dual sensory loss protocol and design of a randomized controlled trial

Background

Dual sensory loss (DSL) has a negative impact on health and wellbeing and its prevalence is expected to increase due to demographic aging. However, specialized care or rehabilitation programs for DSL are scarce. Until now, low vision rehabilitation does not sufficiently target concurrent impairments in vision and hearing. This study aims to 1) develop a DSL protocol (for occupational therapists working in low vision rehabilitation) which focuses on optimal use of the senses and teaches DSL patients and their communication partners to use effective communication strategies, and 2) describe the multicenter parallel randomized controlled trial (RCT) designed to test the effectiveness and cost-effectiveness of the DSL protocol.

Methods/design

To develop a DSL protocol, literature was reviewed and content was discussed with professionals in eye/ear care (interviews/focus groups) and DSL patients (interviews). A pilot study was conducted to test and confirm the DSL protocol. In addition, a two-armed international multi-center RCT will evaluate the effectiveness and cost-effectiveness of the DSL protocol compared to waiting list controls, in 124 patients in low vision rehabilitation centers in the Netherlands and Belgium.

Discussion

This study provides a treatment protocol for rehabilitation of DSL within low vision rehabilitation, which aims to be a valuable addition to the general low vision rehabilitation care.

Trial registration

Netherlands Trial Register (NTR) identifier: NTR2843

Predicting foreign-accent adaptation in older adults

We investigated comprehension of and adaptation to speech in an unfamiliar accent in older adults. Participants performed a speeded sentence verification task for accented sentences: one group upon auditory-only presentation, and the other group upon audiovisual presentation. Our questions were whether audiovisual presentation would facilitate adaptation to the novel accent, and which cognitive and linguistic measures would predict adaptation. Participants were therefore tested on a range of background tests: hearing acuity, auditory verbal short-term memory, working memory, attention-switching control, selective attention, and vocabulary knowledge. Both auditory-only and audiovisual groups showed improved accuracy and decreasing response times over the course of the experiment, effectively showing accent adaptation. Even though the total amount of improvement was similar for the auditory-only and audiovisual groups, initial rate of adaptation was faster in the audiovisual group. Hearing sensitivity and short-term and working memory measures were associated with efficient processing of the novel accent. Analysis of the relationship between accent comprehension and the background tests revealed furthermore that selective attention and vocabulary size predicted the amount of adaptation over the course of the experiment. These results suggest that vocabulary knowledge and attentional abilities facilitate the attention-shifting strategies proposed to be required for perceptual learning.

Neural mechanisms underlying neurooptometric rehabilitation following traumatic brain injury

Mild to severe traumatic brain injuries have lasting effects on everyday functioning. Issues relating to sensory problems are often overlooked or not addressed until well after the onset of the injury. In particular, vision problems related to ambient vision and the magnocellular pathway often result in posttrauma vision syndrome or visual midline shift syndrome. Symptoms from these syndromes are not restricted to the visual domain. Patients commonly experience proprioceptive, kinesthetic, vestibular, cognitive, and language problems. Neurooptometric rehabilitation often entails the use of corrective lenses, prisms, and binasal occlusion to accommodate the unstable magnocellular system. However, little is known regarding the neural mechanisms engaged during neurooptometric rehabilitation, nor how these mechanisms impact other domains. Event-related potentials from noninvasive electrophysiological recordings can be used to assess rehabilitation progress in patients. In this case report, high-density visual event-related potentials were recorded from one patient with posttrauma vision syndrome and secondary visual midline shift syndrome during a pattern reversal task, both with and without prisms. Results indicate that two factors occurring during the end portion of the P148 component (168–256 milliseconds poststimulus onset) map onto two separate neural systems that were engaged with and without neurooptometric rehabilitation. Without prisms, neural sources within somatosensory, language, and executive brain regions engage inefficient magnocellular system processing. However, when corrective prisms were worn, primary visual areas were appropriately engaged. The impact of using early neurooptometric rehabilitation for posttrauma vision syndrome, visual midline shift syndrome, and other similar subtle vision disorders to support neural reorganization is discussed.