Influence of Postponed Follow-Up after Cochlear Implant Activation during the COVID-19 Pandemic on Aided Sound Field Detection and Speech Recognition

<b><i>Introduction:</i></b> The objective of this study was to assess the influence of postponing the first post-activation follow-up due to the COVID-19 pandemic on the aided sound field detection thresholds and speech recognition of cochlear implant (CI) users. <b><i>Methods:</i></b> A retrospective review was performed at a tertiary referral center. Two groups of adult CI recipients were evaluated: (1) patients whose first post-activation follow-up was postponed due to COVID-19 closures (postponed group; <i>n</i> = 10) and (2) a control group that attended recommended post-activation follow-ups prior to the COVID-19 pandemic (control group; <i>n</i> = 18). For both groups, electric thresholds were estimated at initial activation based on comfort levels and were measured behaviorally at subsequent post-activation follow-ups. For the control group, behavioral thresholds were measured at the 1-month follow-up. For the postponed group, behavioral thresholds were not measured until 3 months post-activation since the 1-month follow-up was postponed. The aided pure-tone average (PTA) and word recognition results were compared between groups at the 3-month follow-up and at an interim visit 2–9 weeks later. <b><i>Results:</i></b> At the 3-month follow-up, the postponed group had significantly poorer word recognition (23 vs. 42%, <i>p</i> = 0.027) and aided PTA (42 vs. 37 dB HL, <i>p</i> = 0.041) than the control group. No significant differences were observed between 3-month data from the control group and interim data from the postponed group. <b><i>Conclusions:</i></b> The postponed follow-up after CI activation was associated with poorer outcomes, both in terms of speech recognition and aided audibility. However, these detrimental effects were reversed following provision of an individualized map, with behaviorally measured electric threshold and comfort levels. While adult CI recipients demonstrate an improvement in speech recognition with estimated electric thresholds, the present results suggest that behavioral mapping within the initial weeks of device use may support optimal outcomes.

Similar masking effects of natural backgrounds on detection performances in humans, macaques, and macaque-V1 population responses

Visual systems evolve to process the stimuli that arise in the organism's natural environment and hence to fully understand the neural computations in the visual system it is important to measure behavioral and neural responses to natural visual stimuli. Here we measured psychometric and neurometric functions and thresholds in the macaque monkey for detection of a windowed sine‐wave target in uniform backgrounds and in natural backgrounds of various contrasts. The neurometric functions and neurometric thresholds were obtained by near‐optimal decoding of voltage‐sensitive‐dye‐imaging (VSDI) responses at the retinotopic scale in primary visual cortex (V1). Results were compared with previous human psychophysical measurements made under the same conditions. We found that human and macaque behavioral thresholds followed the generalized Weber's law as function of contrast, and that both the slopes and the intercepts of the threshold functions match each other up to a single scale factor. We also found that the neurometric thresholds followed the generalized Weber's law and that the neurometric slopes and intercepts matched the behavioral slopes and intercepts up to a single scale factor. We conclude that human and macaque ability to detect targets in natural backgrounds are affected in the same way by background contrast, that these effects are consistent with population decoding at the retinotopic scale by down‐stream circuits, and that the macaque monkey is an appropriate animal model for gaining an understanding of the neural mechanisms in humans for detecting targets in natural backgrounds. Finally, we discuss limitations of the current study and potential next steps.

Microsecond interaural time difference discrimination restored by cochlear implants after neonatal deafness

Spatial hearing in cochlear implant (CI) patients remains a major challenge with many early deaf users reported to have no measurable sensitivity to interaural time differences (ITDs). Deprivation of binaural experience during an early critical period is often hypothesized to be the cause of this shortcoming. However, we show that neonatally deafened (ND) rats provided with precisely synchronized CI stimulation in adulthood can be trained to lateralize ITDs with essentially normal behavioral thresholds near 50 μs. Furthermore, comparable ND rats show high physiological sensitivity to ITDs immediately after binaural implantation in adulthood. Our result that ND CI rats achieved very good behavioral ITD thresholds while prelingually deaf human CI patients often fail to develop a useful sensitivity to ITD raises urgent questions concerning the possibility that shortcomings in technology or treatment, rather than missing input during early development, may be behind the usually poor binaural outcomes for current CI patients.

An integrative approach for pediatric auditory neuropathy spectrum disorders: revisiting etiologies and exploring the prognostic utility of auditory steady-state response

Auditory neuropathy is an important entity in childhood sensorineural hearing loss. Due to diverse etiologies and clinical features, the management is often challenging. This study used an integrative patient-history, audiologic, genetic, and imaging-based approach to investigate the etiologies and audiologic features of 101 children with auditory neuropathy. Etiologically, 48 (47.5%), 16 (15.8%), 11 (10.9%), and 26 (25.7%) children were categorized as having acquired, genetic, cochlear nerve deficiency-related, and indefinite auditory neuropathy, respectively. The most common causes of acquired and genetic auditory neuropathy were prematurity and OTOF mutations, respectively. Patients with acquired auditory neuropathy presented hearing loss earlier (odds ratio, 10.2; 95% confidence interval, 2.2–47.4), whereas patients with genetic auditory neuropathy had higher presence rate of distortion product otoacoustic emissions (odds ratio, 10.7; 95% confidence interval, 1.3–85.4). In patients with different etiologies or pathological sites, moderate to strong correlations (Pearson’s r = 0.51–0.83) were observed between behavioral thresholds and auditory steady-state response thresholds. In conclusion, comprehensive assessments can provide etiological clues in ~75% of the children with auditory neuropathy. Different etiologies are associated with different audiologic features, and auditory steady-state responses might serve as an objective measure for estimating behavioral thresholds.

Human Depth Sensitivity Is Affected by Object Plausibility

Using behavioral and fMRI paradigms, we asked how the physical plausibility of complex 3-D objects, as defined by the object's congruence with 3-D Euclidean geometry, affects behavioral thresholds and neural responses to depth information. Stimuli were disparity-defined geometric objects rendered as random dot stereograms, presented in plausible and implausible variations. In the behavior experiment, observers were asked to complete (1) a noise-based depth task that involved judging the depth position of a target embedded in noise and (2) a fine depth judgment task that involved discriminating the nearer of two consecutively presented targets. Interestingly, results indicated greater behavioral sensitivities of depth judgments for implausible versus plausible objects across both tasks. In the fMRI experiment, we measured fMRI responses concurrently with behavioral depth responses. Although univariate responses for depth judgments were largely similar across cortex regardless of object plausibility, multivariate representations for plausible and implausible objects were notably distinguishable along depth-relevant intermediate regions V3 and V3A, in addition to object-relevant LOC. Our data indicate significant modulations of both behavioral judgments of and neural responses to depth by object context. We conjecture that disparity mechanisms interact dynamically with the object recognition problem in the visual system such that disparity computations are adjusted based on object familiarity.

Registration of assr-thresholds in free field stimulation in normal hearing persons. Our experience

Background: Currently, for an objective assessment of the thresholds of auditory sensitivity, one of the most popular diagnostic methods is the method of recording of auditory steady state response - the ASSR test. One of the primary uses of ASSR is to assess sound thresholds correlated with tonal threshold audiometry. Actually, there are no reliable criteria for the norm for this study with free field stimulation, in conditions close to the natural listening environment. The identification of these criteria will allow this method to be applied as a routine in patients who cannot be tested in the usual way using headsets or in-ear phones (headphones). Objective: To determine the correlation of the ASSR thresholds with free field stimulation and the responses of insert-transducers stimulation and values of tonal threshold audiometry in the free field in normally hearing individuals. Design: Behavioral thresholds in a free field were compared with the results of ASSR in 20 normally hearing adults (40 ears) with stimulus delivery both via insert-transducers and using a loudspeaker. Conclusion: The ASSR thresholds in normal hearing adults obtained by free field were comparable to the thresholds obtained with a stimulus through insert- transducers and the results of behavioral thresholds. The correction coefficients for measuring ASSR thresholds and behavioral thresholds in free field in normal hearing adults have been obtained.

Pure-tone audiometry using portable screening system in groups of students

Background: according to WHO estimates, there are more than 466 million (over 6% of the population) with hearing impairments in the world. The limited availability of specialized audiological equipment, as well as the routing of such patients, complicates early diagnosis, which can negatively affect the results of treatment and rehabilitation. Devices (complexes) of automatic audiometry demonstrate the possibility of obtaining results comparable to the data of the pure tone audiogram. The study presents the results of approbation of the hardware and software complex «Colibri», which was developed to control and analyze the health parameters in students of general educational institutions, as well as educational institutions that carry out educational activities according to the adapted basic general educational programs. Objective: to determine the correlation of the thresholds of sound perception, identified by screening audiometry with the values of the pure tone audiometry in a group of normally hearing schoolchildren. Study design: a comparison was made of the behavioral thresholds of sound perception obtained using screening audiometry with the values of the pure tone audiometry threshold in 35 normally hearing students. Conclusion: further study of the technique is required to create a test protocol with the aim of possible use for identifying persons with possible hearing impairment. The use of such a system does not require the participation of a specialist - an audiologist, which makes it possible to carry out screening tests outside the hospital, subject to the technical (acoustic) requirements.

Intraoperative Estimation of the Coupling Efficiency and Clinical Outcomes of the Vibrant Soundbridge Active Middle Ear Implant Using Auditory Brainstem Response Measurements

Purpose This study intraoperatively measured the coupling efficiency of the Vibrant Soundbridge (VSB), with the aim of avoiding revision surgery due to insufficient outcome. This method can also be used to test the integrity of the implant at the end of the implantation surgery and to evaluate aided thresholds. In addition, this method makes it possible to objectively test how well the VSB has been fitted, provide assistance in fitting handicapped patients or children, evaluate hearing degradation, or test for a drop in coupling efficiency before revision surgeries. In order to analyze the feasibility of these new VSB-aided auditory brainstem response (ABR) thresholds, they were compared to behavioral thresholds from the Vibrogram and the preoperative bone conduction thresholds. Method The study included 30 patients with mild-to-severe hearing loss implanted with a VSB (VORP503). Intraoperative ABR thresholds during the VSB implantation were recorded using a VSB-optimized chirp stimulus. The new method is compared to the bone conduction threshold of the study sample and the aided Vibrogram thresholds. Speech intelligibility results up to 24 months after surgery are also presented. Results A reliable correlation between the bone conduction thresholds and the intraoperative ABRs was found and was higher in comparison to the Vibrogram. Furthermore, speech intelligibility outcomes were stable over time. Conclusion ABR measurements can be used intraoperatively to estimate the coupling efficiency of the VSB and test the integrity of the implant at the end of surgery.