The Influence of Linguistic Proficiency on Masked Text Recognition Performance in Adults With and Without Congenital Hearing Impairment

Objective: The authors first examined the influence of moderate to severe congenital hearing impairment (CHI) on the correctness of samples of elicited spoken language. Then, the authors used this measure as an indicator of linguistic proficiency and examined its effect on performance in language reception, independent of bottom-up auditory processing. Design: In groups of adults with normal hearing (NH, n = 22), acquired hearing impairment (AHI, n = 22), and moderate to severe CHI (n = 21), the authors assessed linguistic proficiency by analyzing the morphosyntactic correctness of their spoken language production. Language reception skills were examined with a task for masked sentence recognition in the visual domain (text), at a readability level of 50%, using grammatically correct sentences and sentences with distorted morphosyntactic cues. The actual performance on the tasks was compared between groups. Results: Adults with CHI made more morphosyntactic errors in spoken language production than adults with NH, while no differences were observed between the AHI and NH group. This outcome pattern sustained when comparisons were restricted to subgroups of AHI and CHI adults, matched for current auditory speech reception abilities. The data yielded no differences between groups in performance in masked text recognition of grammatically correct sentences in a test condition in which subjects could fully take advantage of their linguistic knowledge. Also, no difference between groups was found in the sensitivity to morphosyntactic distortions when processing short masked sentences, presented visually. Conclusions: These data showed that problems with the correct use of specific morphosyntactic knowledge in spoken language production are a long-term effect of moderate to severe CHI, independent of current auditory processing abilities. However, moderate to severe CHI generally does not impede performance in masked language reception in the visual modality, as measured in this study with short, degraded sentences. Aspects of linguistic proficiency that are affected by CHI thus do not seem to play a role in masked sentence recognition in the visual modality.

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Association Between Osteoporosis/Osteopenia and Vestibular Dysfunction in South Korean Adults

Objective: The associations of osteoporosis/osteopenia with vestibular dysfunction have not been well evaluated and conflicting results have been reported. The purpose of this study is to examine the relation of low bone mineral density (BMD) with vestibular dysfunction. Design: The authors conducted a cross-sectional study in 3579 Korean adults aged 50 years and older who participated in the 2009 to 2010 Korea National Health and Nutrition Examination Survey. BMD was measured by dual energy X ray absorptiometry. Vestibular dysfunction was evaluated using the modified Romberg test of standing balance on firm and compliant support surfaces. Data were analyzed in 2015. Multiple logistic regression analysis was used to compute odds ratios (ORs) and 95% confidence intervals (CIs). Results: The prevalence of vestibular dysfunction was 4.3 ± 0.5%. After adjustment for potential confounders, the adjusted ORs for vestibular dysfunction based on BMD were 1.00 (reference) for normal BMD, 2.21 (95% CI: 1.08, 4.50) for osteopenia, and 2.47 (95% CI: 1.05, 5.81) for osteoporosis (p

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Reflectance Measures from Infant Ears With Normal Hearing and Transient Conductive Hearing Loss

Objective: The objective is to develop methods to utilize newborn reflectance measures for the identification of middle-ear transient conditions (e.g., middle-ear fluid) during the newborn period and ultimately during the first few months of life. Transient middle-ear conditions are a suspected source of failure to pass a newborn hearing screening. The ability to identify a conductive loss during the screening procedure could enable the referred ear to be either (1) cleared of a middle-ear condition and recommended for more extensive hearing assessment as soon as possible, or (2) suspected of a transient middle-ear condition, and if desired, be rescreened before more extensive hearing assessment. Design: Reflectance measurements are reported from full-term, healthy, newborn babies in which one ear referred and one ear passed an initial auditory brainstem response newborn hearing screening and a subsequent distortion product otoacoustic emission screening on the same day. These same subjects returned for a detailed follow-up evaluation at age 1 month (range 14 to 35 days). In total, measurements were made on 30 subjects who had a unilateral refer near birth (during their first 2 days of life) and bilateral normal hearing at follow-up (about 1 month old). Three specific comparisons were made: (1) Association of ear’s state with power reflectance near birth (referred versus passed ear), (2) Changes in power reflectance of normal ears between newborn and 1 month old (maturation effects), and (3) Association of ear’s newborn state (referred versus passed) with ear’s power reflectance at 1 month. In addition to these measurements, a set of preliminary data selection criteria were developed to ensure that analyzed data were not corrupted by acoustic leaks and other measurement problems. Results: Within 2 days of birth, the power reflectance measured in newborn ears with transient middle-ear conditions (referred newborn hearing screening and passed hearing assessment at age 1 month) was significantly greater than power reflectance on newborn ears that passed the newborn hearing screening across all frequencies (500 to 6000 Hz). Changes in power reflectance in normal ears from newborn to 1 month appear in approximately the 2000 to 5000 Hz range but are not present at other frequencies. The power reflectance at age 1 month does not depend significantly on the ear’s state near birth (refer or pass hearing screening) for frequencies above 700 Hz; there might be small differences at lower frequencies. Conclusions: Power reflectance measurements are significantly different for ears that pass newborn hearing screening and ears that refer with middle-ear transient conditions. At age 1 month, about 90% of ears that referred at birth passed an auditory brainstem response hearing evaluation; within these ears the power reflectance at 1 month did not differ between the ear that initially referred at birth and the ear that passed the hearing screening at birth for frequencies above 700 Hz. This study also proposes a preliminary set of criteria for determining when reflectance measures on young babies are corrupted by acoustic leaks, probes against the ear canal, or other measurement problems. Specifically proposed are “data selection criteria” that depend on the power reflectance, impedance magnitude, and impedance angle. Additional data collected in the future are needed to improve and test these proposed criteria.

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The Physiological Basis and Clinical Use of the Binaural Interaction Component of the Auditory Brainstem Response

The auditory brainstem response (ABR) is a sound-evoked noninvasively measured electrical potential representing the sum of neuronal activity in the auditory brainstem and midbrain. ABR peak amplitudes and latencies are widely used in human and animal auditory research and for clinical screening. The binaural interaction component (BIC) of the ABR stands for the difference between the sum of the monaural ABRs and the ABR obtained with binaural stimulation. The BIC comprises a series of distinct waves, the largest of which (DN1) has been used for evaluating binaural hearing in both normal hearing and hearing-impaired listeners. Based on data from animal and human studies, the authors discuss the possible anatomical and physiological bases of the BIC (DN1 in particular). The effects of electrode placement and stimulus characteristics on the binaurally evoked ABR are evaluated. The authors review how interaural time and intensity differences affect the BIC and, analyzing these dependencies, draw conclusion about the mechanism underlying the generation of the BIC. Finally, the utility of the BIC for clinical diagnoses are summarized.

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A Novel Algorithm to Derive Spread of Excitation Based on Deconvolution

Objective: The width of the spread of excitation (SOE) curve has been widely thought to represent an estimate of SOE. Therefore, correlates between psychophysical parameters, such as pitch discrimination and speech perception, and the width of SOE curves, have long been investigated. However, to date, no relationships between these objective and subjective measurements have yet been determined. In a departure from the current thinking, the authors now propose that the SOE curve, recorded with forward masking, is the equivalent of a convolution operation. As such, deconvolution would be expected to retrieve the excitation areas attributable to either masker or probe, potentially more closely revealing the actual neural SOE. This study aimed to develop a new analytical tool with which to derive SOE using this principle. Design: Intraoperative SOE curve measurements of 16 subjects, implanted with an Advanced Bionics implant, were analyzed. Evoked compound action potential (ECAP)-based SOE curves were recorded on electrodes 3 to 16, using the forward masker paradigm, with variable masker. The measured SOE curves were then compared with predicted SOE curves, built by the convolution of basic excitation density profiles (EDPs). Predicted SOE curves were fitted to the measured SOEs by iterative adjustment of the EDPs for the masker and the probe. Results: It was possible to generate a good fit between the predicted and measured SOE curves, inclusive of their asymmetry. The rectangular EDP was of least value in terms of its ability to generate a good fit; smoother SOE curves were modeled using the exponential or Gaussian EDPs. In most subjects, the EDP width (i.e., the size of the excitation area) gradually changed from wide at the apex of the electrode array, to narrow at the base. A comparison of EDP widths to SOE curve widths, as calculated in the literature, revealed that the EDPs now provide a measure of the SOE that is qualitatively distinct from that provided using conventional methods. Conclusions: This study shows that an eCAP-based SOE curve, measured with forward masking, can be treated as a convolution of EDPs for masker and probe. The poor fit achieved for the measured and modeled data using the rectangular EDP, emphasizes the requirement for a sloping excitation area to mimic actual SOE recordings. Our deconvolution method provides an explanation for the frequently observed asymmetry of SOE curves measured along the electrode array, as this is a consequence of a wider excitation area in the apical part of the cochlea, in the absence of any asymmetry in the actual EDP. In addition, broader apical EDPs underlie the higher eCAP amplitudes found for apical stimulation.

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Intelligibility of the Patient’s Speech Predicts the Likelihood of Cochlear Implant Success in Prelingually Deaf Adults

Objectives: The objective of this study was to determine the validity and clinical applicability of intelligibility of the patient’s own speech, measured via a Vowel Identification Test (VOW), as a predictor of speech perception for prelingually deafened adults after 1 year of cochlear implant use. Specifically, the objective was to investigate the probability that a prelingually deaf patient, given a VOW score above (or below) a chosen cutoff point, reaches a postimplant speech perception score above (or below) a critical value. High predictive values for VOW could support preimplant counseling and implant candidacy decisions in individual patients. Design: One hundred and fifty-two adult cochlear implant candidates with prelingual hearing impairment or deafness took part as speakers in a VOW; 149 speakers completed the test successfully. Recordings of the speech stimuli, consisting of nonsense words of the form [h]-V-[t], where V represents one of 15 vowels/diphthongs ([ ]), were presented to two normal-hearing listeners. VOW score was expressed as the percentage of vowels identified correctly (averaged over the 2 listeners). Subsequently, the 149 participants enrolled in the cochlear implant selection procedure. Extremely poor speakers were excluded from implantation, as well as patients who did not meet regular selection criteria as developed for postlingually deafened patients. From the 149 participants, 92 were selected for implantation. For the implanted group, speech perception data were collected at 1-year postimplantation. Results: Speech perception score at 1-year postimplantation (available for 77 of the 92 implanted participants) correlated positively with preimplant intelligibility of the patient’s speech, as represented by VOW (r = 0.79, p

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Top-Down Processes in Simulated Electric-Acoustic Hearing: The Effect of Linguistic Context on Bimodal Benefit for Temporally Interrupted Speech

Objectives: Previous studies have documented the benefits of bimodal hearing as compared with a cochlear implant alone, but most have focused on the importance of bottom-up, low-frequency cues. The purpose of the present study was to evaluate the role of top-down processing in bimodal hearing by measuring the effect of sentence context on bimodal benefit for temporally interrupted sentences. It was hypothesized that low-frequency acoustic cues would facilitate the use of contextual information in the interrupted sentences, resulting in greater bimodal benefit for the higher context (CUNY) sentences than for the lower context (IEEE) sentences. Design: Young normal-hearing listeners were tested in simulated bimodal listening conditions in which noise band vocoded sentences were presented to one ear with or without low-pass (LP) filtered speech or LP harmonic complexes (LPHCs) presented to the contralateral ear. Speech recognition scores were measured in three listening conditions: vocoder-alone, vocoder combined with LP speech, and vocoder combined with LPHCs. Temporally interrupted versions of the CUNY and IEEE sentences were used to assess listeners’ ability to fill in missing segments of speech by using top-down linguistic processing. Sentences were square-wave gated at a rate of 5 Hz with a 50% duty cycle. Three vocoder channel conditions were tested for each type of sentence (8, 12, and 16 channels for CUNY; 12, 16, and 32 channels for IEEE) and bimodal benefit was compared for similar amounts of spectral degradation (matched-channel comparisons) and similar ranges of baseline performance. Two gain measures, percentage-point gain and normalized gain, were examined. Results: Significant effects of context on bimodal benefit were observed when LP speech was presented to the residual-hearing ear. For the matched-channel comparisons, CUNY sentences showed significantly higher normalized gains than IEEE sentences for both the 12-channel (20 points higher) and 16-channel (18 points higher) conditions. For the individual gain comparisons that used a similar range of baseline performance, CUNY sentences showed bimodal benefits that were significantly higher (7% points, or 15 points normalized gain) than those for IEEE sentences. The bimodal benefits observed here for temporally interrupted speech were considerably smaller than those observed in an earlier study that used continuous speech. Furthermore, unlike previous findings for continuous speech, no bimodal benefit was observed when LPHCs were presented to the LP ear. Conclusions: Findings indicate that linguistic context has a significant influence on bimodal benefit for temporally interrupted speech and support the hypothesis that low-frequency acoustic information presented to the residual-hearing ear facilitates the use of top-down linguistic processing in bimodal hearing. However, bimodal benefit is reduced for temporally interrupted speech as compared with continuous speech, suggesting that listeners’ ability to restore missing speech information depends not only on top-down linguistic knowledge but also on the quality of the bottom-up sensory input.

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