Effects of an evidence-based model for cochlear implant aftercare delivery on clinical efficiency and patient outcomes.

OBJECTIVES: To assess an evidence-based model (EBM) approach to cochlear implant (CI) aftercare that includes a modified, reduced treatment schedule for newly-implanted adult CI recipients consisting of four appointments (initial activation, 1-, 3- and 6- months postactivation) in the first year post-surgery. METHOD: This prospective multicenter proof-of-concept study was conducted across three clinics in the United States by five experienced CI clinicians. Seventeen newly-implanted adult patients with postlingual hearing loss enrolled in the study. Hearing outcomes were measured using objective speech testing and subjective self-report measures. RESULTS: Most recipients (14/17; 82%) were able to follow the four-appointment EBM schedule. The reduced number of visits translated into an average time savings of 3 hours per patient. Significant improvements in speech perception were observed at both 3- and 6-months postactivation, as measured by CNC words in quiet and AzBio sentences at +10 dB SNR, consistent with published results achieved by traditional practices. Recipients were significantly satisfied with telephone, music, small group conversation, and television listening at 6 months postactivation. Recipient satisfaction with overall service was rated as "excellent" by 14/14 (100%) respondents. CONCLUSION: The four-appointment EBM approach delivered efficient and effective audiological aftercare to CI recipients in the first year following CI implantation.

Changes in Heart Rate Variability Following Acoustic Therapy in Individuals With Tinnitus.

Purpose The aim of the study was to investigate changes in autonomic function, as measured by heart rate variability, in individuals with tinnitus following acoustic therapy implemented using tinnitus maskers presented via hearing aids. Method Twenty-six individuals with tinnitus and hearing impairment completed an 8-week field trial wearing hearing aids providing acoustic therapy via three tinnitus masker options set just below minimum masking level. Tinnitus handicap was measured using the Tinnitus Handicap Inventory at baseline (before starting acoustic therapy) and posttreatment (at end of 8-week trial). Resting heart rate and heart rate variability were measured using electrocardiography at baseline and posttreatment. Results There was a significant decrease in tinnitus handicap posttreatment compared to baseline. There was no change in heart rate, but there was a significant increase in heart rate variability posttreatment compared to baseline. Conclusions Acoustic therapy using tinnitus maskers delivered via hearing aids provided tinnitus relief and produced a concurrent increase in heart rate variability, suggesting a decrease in stress. Heart rate variability is a potential biomarker for tracking efficacy of acoustic therapy; however, further research is required.

Interactions Between Digital Noise Reduction and Reverberation: Acoustic and Behavioral Effects.

BACKGROUND: Digital noise reduction (DNR) processing is used in hearing aids to enhance perception in noise by classifying and suppressing the noise acoustics. However, the efficacy of DNR processing is not known under reverberant conditions where the speech-in-noise acoustics are further degraded by reverberation. PURPOSE: The purpose of this study was to investigate acoustic and perceptual effects of DNR processing across a range of reverberant conditions for individuals with hearing impairment. RESEARCH DESIGN: This study used an experimental design to investigate the effects of varying reverberation on speech-in-noise processed with DNR. STUDY SAMPLE: Twenty-six listeners with mild-to-moderate sensorineural hearing impairment participated in the study. DATA COLLECTION AND ANALYSIS: Speech stimuli were combined with unmodulated broadband noise at several signal-to-noise ratios (SNRs). A range of reverberant conditions with realistic parameters were simulated, as well as an anechoic control condition without reverberation. Reverberant speech-in-noise signals were processed using a spectral subtraction DNR simulation. Signals were acoustically analyzed using a phase inversion technique to quantify improvement in SNR as a result of DNR processing. Sentence intelligibility and subjective ratings of listening effort, speech naturalness, and background noise comfort were examined with and without DNR processing across the conditions. RESULTS: Improvement in SNR was greatest in the anechoic control condition and decreased as the ratio of direct to reverberant energy decreased. There was no significant effect of DNR processing on speech intelligibility in the anechoic control condition, but there was a significant decrease in speech intelligibility with DNR processing in all of the reverberant conditions. Subjectively, listeners reported greater listening effort and lower speech naturalness with DNR processing in some of the reverberant conditions. Listeners reported higher background noise comfort with DNR processing only in the anechoic control condition. CONCLUSIONS: Results suggest that reverberation affects DNR processing using a spectral subtraction algorithm in such a way that decreases the ability of DNR to reduce noise without distorting the speech acoustics. Overall, DNR processing may be most beneficial in environments with little reverberation and that the use of DNR processing in highly reverberant environments may actually produce adverse perceptual effects. Further research is warranted using commercial hearing aids in realistic reverberant environments.

The evaluation of inhalation studies for exposure quality: A case study with formaldehyde.

The inherent complexity of generating and monitoring a test article in an inhalation chamber can make inhalation toxicity testing challenging. Poor study design, human error, and electrical and mechanical problems can adversely affect an inhalation exposure and undermine a study's results. We have developed a process for evaluating seven key elements of exposure quality in inhalation chamber studies: 1) test article characterization, 2) generation method, 3) chamber sampling and analytical method, 4) chamber concentrations, 5) particle size characteristics, 6) chamber type, and 7) controls. For each study evaluated, exposure deficiencies are documented, and a study is given an overall rating (Robust, Adequate, or Poor) for the quality of its exposure characterization and documentation. In combination with the systematic consideration of experimental features other than exposure, these ratings can inform the utility of a study for use in hazard identification and/or exposure-response analysis. Exposure quality evaluations of 204 formaldehyde inhalation studies are presented as a case study. Of these, 34% were rated Robust because they had comprehensive exposure documentation and no serious deficiencies in the key elements of exposure quality. Another 19% of studies with minor uncertainties or limitations were rated Adequate. Conversely, 47% of the studies were rated Poor due to multiple serious exposure deficiencies. This formaldehyde case study illustrates the need to carefully consider the exposure quality of inhalation toxicity studies when their results are used to support hazard and risk assessments.

Effects of Reverberation on the Relation Between Compression Speed and Working Memory for Speech-in-Noise Perception.

OBJECTIVES: Previous study has suggested that when listening in modulated noise, individuals benefit from different wide dynamic range compression (WDRC) speeds depending on their working memory ability. Reverberation reduces the modulation depth of signals and may impact the relation between WDRC speed and working memory. The purpose of this study was to examine this relation across a range of reverberant conditions. DESIGN: Twenty-eight older listeners with mild-to-moderate sensorineural hearing impairment were recruited in the present study. Individual working memory was measured using a Reading Span test. Sentences were combined with noise at two signal to noise ratios (2 and 5 dB SNR), and reverberation was simulated at a range of reverberation times (0.00, 0.75, 1.50, and 3.00 sec). Speech intelligibility was measured in listeners when listening to the sentences processed with simulated fast-acting and slow-acting WDRC conditions. RESULTS: There was a significant relation between WDRC speed and working memory with minimal or no reverberation. Consistent with previous research, this relation was such that individuals with high working memory had higher speech intelligibility with fast-acting WDRC, and individuals with low working memory performed better with slow-acting WDRC. However, at longer reverberation times, there was no relation between WDRC speed and working memory. CONCLUSIONS: Consistent with previous studies, results suggest that there is an advantage of tailoring WDRC speed based on an individual's working memory under anechoic conditions. However, the present results further suggest that there may not be such a benefit in reverberant listening environments due to reduction in signal modulation.

Reliability and Repeatability of the Speech Cue Profile.

Purpose: Researchers have long noted speech recognition variability that is not explained by the pure-tone audiogram. Previous work (Souza, Wright, Blackburn, Tatman, & Gallun, 2015) demonstrated that a small number of listeners with sensorineural hearing loss utilized different types of acoustic cues to identify speechlike stimuli, specifically the extent to which the participant relied upon spectral (or temporal) information for identification. Consistent with recent calls for data rigor and reproducibility, the primary aims of this study were to replicate the pattern of cue use in a larger cohort and to verify stability of the cue profiles over time. Method: Cue-use profiles were measured for adults with sensorineural hearing loss using a syllable identification task consisting of synthetic speechlike stimuli in which spectral and temporal dimensions were manipulated along continua. For the first set, a static spectral shape varied from alveolar to palatal, and a temporal envelope rise time varied from affricate to fricative. For the second set, formant transitions varied from labial to alveolar and a temporal envelope rise time varied from approximant to stop. A discriminant feature analysis was used to determine to what degree spectral and temporal information contributed to stimulus identification. A subset of participants completed a 2nd visit using the same stimuli and procedures. Results: When spectral information was static, most participants were more influenced by spectral than by temporal information. When spectral information was dynamic, participants demonstrated a balanced distribution of cue-use patterns, with nearly equal numbers of individuals influenced by spectral or temporal cues. Individual cue profile was repeatable over a period of several months. Conclusion: In combination with previously published data, these results indicate that listeners with sensorineural hearing loss are influenced by different cues to identify speechlike sounds and that those patterns are stable over time.

Effects of Varying Reverberation on Music Perception for Young Normal-Hearing and Old Hearing-Impaired Listeners.

Reverberation enhances music perception and is one of the most important acoustic factors in auditorium design. However, previous research on reverberant music perception has focused on young normal-hearing (YNH) listeners. Old hearing-impaired (OHI) listeners have degraded spatial auditory processing; therefore, they may perceive reverberant music differently. Two experiments were conducted examining the effects of varying reverberation on music perception for YNH and OHI listeners. Experiment 1 examined whether YNH listeners and OHI listeners prefer different amounts of reverberation for classical music listening. Symphonic excerpts were processed at a range of reverberation times using a point-source simulation. Listeners performed a paired-comparisons task in which they heard two excerpts with different reverberation times, and they indicated which they preferred. The YNH group preferred a reverberation time of 2.5 s; however, the OHI group did not demonstrate any significant preference. Experiment 2 examined whether OHI listeners are less sensitive to (e, less able to discriminate) differences in reverberation time than YNH listeners. YNH and OHI participants listened to pairs of music excerpts and indicated whether they perceived the same or different amount of reverberation. Results indicated that the ability of both groups to detect differences in reverberation time improved with increasing reverberation time difference. However, discrimination was poorer for the OHI group than for the YNH group. This suggests that OHI listeners are less sensitive to differences in reverberation when listening to music than YNH listeners, which might explain the lack of group reverberation time preferences of the OHI group.

Listener Factors Associated with Individual Susceptibility to Reverberation.

BACKGROUND: Reverberation is a source of acoustic degradation, present to varying extents in many everyday listening environments. The presence of reverberation decreases speech intelligibility, especially for listeners with hearing impairment. There is substantial variability in how susceptible individuals with hearing impairment are to the effects of reverberation (i.e., how intelligible reverberant speech is to a listener). Relatively little is known about the listener factors which drive that susceptibility. PURPOSE: To identify listener factors that are associated with an individual's susceptibility to reverberation. Another purpose was to investigate how these listener factors are associated with reverberant susceptibility in relation to the amount of reverberation. The listener factors investigated were degree of hearing loss, age, temporal envelope sensitivity, and working memory capacity. RESEARCH DESIGN: This study used a correlational design to investigate the association between different listener factors and speech intelligibility with varying amounts of reverberation. STUDY SAMPLE: Thirty-three older adults with sensorineural hearing loss participated in the study. DATA COLLECTION AND ANALYSIS: Listener temporal envelope sensitivity was measured using a gap detection threshold task. Listener working memory capacity was measured using the Reading Span Test. Intelligibility of reverberant speech was measured using a set of low-context sentence materials presented at 70 dB SPL without individual frequency shaping. Sentences were presented at a range of realistic reverberation times, including no reverberation (0.0 sec), moderate reverberation (1.0 sec), and severe reverberation (4.0 sec). Stepwise linear regression analyses were conducted to model speech intelligibility using individual degree of hearing loss, age, temporal envelope sensitivity, and working memory capacity. A separate stepwise linear regression model was conducted to model listener speech intelligibility at each of the three levels of reverberation. RESULTS: As the amount of reverberation increased, listener speech intelligibility decreased and variability in scores among individuals increased. Temporal envelope sensitivity was most closely associated with speech intelligibility in the no reverberation condition. Both listener age and degree of hearing loss were significantly associated with speech intelligibility in the moderate reverberation condition. Both listener working memory capacity and age were significantly associated with speech intelligibility in the severe reverberation condition. CONCLUSIONS: The results suggest that suprathreshold listener factors can be used to best predict speech intelligibility across a range of reverberant conditions. However, which listener factor(s) to consider when predicting a listener's susceptibility to reverberation depends on the amount of reverberation in an environment. Clinicians may be able to use different listener factors to identify individuals who are more susceptible to reverberation and would be more likely to have difficulty communicating in reverberant environments.

SERUM FERRITIN CONCENTRATION IS NOT A RELIABLE BIOMARKER OF IRON OVERLOAD DISORDER PROGRESSION OR HEMOCHROMATOSIS IN THE SUMATRAN RHINOCEROS (DICERORHINUS SUMATRENSIS).

The aim of this study was to determine if ferritin is a reliable biomarker of iron overload disorder (IOD) progression and hemochromatosis in the Sumatran rhinoceros (Dicerorhinus sumatrensis) by developing a species-specific ferritin assay and testing historically banked samples collected from rhinos that did and did not die of hemochromatosis. Ferritin extracted from Sumatran rhino liver tissue was used to generate antibodies for the Enzyme Immunoassay. Historically banked Sumatran rhino serum samples (n = 298) obtained from six rhinos in US zoos (n = 290); five rhinos at the Sumatran Rhino Conservation Centre in Sungai Dusun, Malaysia (n = 5); and two rhinos in Sabah, Malaysia (n = 3) were analyzed for ferritin concentrations. Across all US zoo samples, serum ferritin concentrations ranged from 348 to 7,071 ng/ml, with individual means ranging from 1,267 (n = 25) to 2,604 ng/ml (n = 36). The ferritin profiles were dynamic, and all rhinos exhibited spikes in ferritin above baseline during the sampling period. The rhino with the highest mean ferritin concentration did not die of hemochromatosis and exhibited only mild hemosiderosis postmortem. A reproductive female exhibited decreases and increases in serum ferritin concurrent with pregnant and nonpregnant states, respectively. Mean (±SD) serum ferritin concentration for Sumatran rhinos in Malaysia was high (4,904 ± 4,828 ng/ml) compared to that for US zoo rhinos (1,835 ± 495 ng/ml). However, those in Sabah had lower ferritin concentrations (1,025 ± 52.7 ng/ml) compared to those in Sungai Dusun (6,456 ± 4,941 ng/ml). In conclusion, Sumatran rhino serum ferritin concentrations are dynamic, and increases often are not associated with illness or hemochromatosis. Neither a specific pattern nor the individual's overall mean ferritin concentration can be used to accurately assess IOD progression or diagnose hemochromatosis in this rhino species.

Effects of reverberation, background talker number, and compression release time on signal-to-noise ratio.

Wide dynamic range compression (WDRC) processing in hearing aids alters the signal-to-noise ratio (SNR) of a speech-in-noise signal. This effect depends on the modulations of the speech and noise, input SNR, and WDRC speed. The purpose of the present experiment was to examine the change in output SNR caused by the interaction between modulation characteristics and WDRC speed. Two modulation manipulations were examined: (1) reverberation and (2) variation in background talker number. Results indicated that fast-acting WDRC altered SNR more than slow-acting WDRC; however, reverberation reduced this difference. Additionally, less modulated maskers led to poorer output SNRs than modulated maskers.

Integrating trans-abdominal ultrasonography with fecal steroid metabolite monitoring to accurately diagnose pregnancy and predict the timing of parturition in the red panda (Ailurus fulgens styani).

Red pandas (Ailurus fulgens styani) exhibit a variable gestation length and may experience a pseudopregnancy indistinguishable from true pregnancy; therefore, it is not possible to deduce an individual's true pregnancy status and parturition date based on breeding dates or fecal progesterone excretion patterns alone. The goal of this study was to evaluate the use of transabdominal ultrasonography for pregnancy diagnosis in red pandas. Two to three females were monitored over 4 consecutive years, generating a total of seven profiles (four pregnancies, two pseudopregnancies, and one lost pregnancy). Fecal samples were collected and assayed for progesterone (P4) and estrogen conjugate (EC) to characterize patterns associated with breeding activity and parturition events. Animals were trained for voluntary transabdominal ultrasound and examinations were performed weekly. Breeding behaviors and fecal EC data suggest that the estrus cycle of this species is 11-12 days in length. Fecal steroid metabolite analyses also revealed that neither P4 nor EC concentrations were suitable indicators of pregnancy in this species; however, a secondary increase in P4 occurred 69-71 days prior to parturition in all pregnant females, presumably coinciding with embryo implantation. Using ultrasonography, embryos were detected as early as 62 days post-breeding/50 days pre-partum and serial measurements of uterine lumen diameter were documented throughout four pregnancies. Advances in reproductive diagnostics, such as the implementation of ultrasonography, may facilitate improved husbandry of pregnant females and allow for the accurate prediction of parturition.

Intelligibility and Clarity of Reverberant Speech: Effects of Wide Dynamic Range Compression Release Time and Working Memory.

Purpose: The purpose of this study was to examine the effects of varying wide dynamic range compression (WDRC) release time on intelligibility and clarity of reverberant speech. The study also considered the role of individual working memory. Method: Thirty older listeners with mild to moderately-severe sloping sensorineural hearing loss participated. Individuals were divided into high and low working memory groups on the basis of the results of a reading span test. Participants listened binaurally to sentence stimuli simulated at a range of reverberation conditions and WDRC release times using a high compression ratio. Outcome measures included objective intelligibility and subjective clarity ratings. Results: Speech intelligibility and clarity ratings both decreased as a function of reverberation. The low working memory group demonstrated a greater decrease in intelligibility with increasing amounts of reverberation than the high working memory group. Both groups, regardless of working memory, had higher speech intelligibility and clarity ratings with longer WDRC release times. WDRC release time had a larger effect on speech intelligibility under more reverberant conditions. Conclusions: Reverberation significantly affects speech intelligibility, particularly for individuals with lower working memory. In addition, longer release times in hearing aids may improve listener speech intelligibility and clarity in reverberant environments.

Effects of Reverberation and Compression on Consonant Identification in Individuals with Hearing Impairment.

OBJECTIVES: Hearing aids are frequently used in reverberant environments; however, relatively little is known about how reverberation affects the processing of signals by modern hearing-aid algorithms. The purpose of this study was to investigate the acoustic and behavioral effects of reverberation and wide-dynamic range compression (WDRC) in hearing aids on consonant identification for individuals with hearing impairment. DESIGN: Twenty-three listeners with mild to moderate sloping sensorineural hearing loss were tested monaurally under varying degrees of reverberation and WDRC conditions. Listeners identified consonants embedded within vowel-consonant-vowel nonsense syllables. Stimuli were processed to simulate a range of realistic reverberation times and WDRC release times using virtual acoustic simulations. In addition, the effects of these processing conditions were acoustically analyzed using a model of envelope distortion to examine the effects on the temporal envelope. RESULTS: Aided consonant identification significantly decreased as reverberation time increased. Consonant identification was also significantly affected by WDRC release time. This relationship was such that individuals tended to perform significantly better with longer release times. There was no significant interaction between reverberation and WDRC. The application of the acoustic model to the processed signal showed a close relationship between trends in the behavioral performance and distortion to the temporal envelope resulting from reverberation and WDRC. The results of the acoustic model demonstrated the same trends found in the behavioral data for both reverberation and WDRC. CONCLUSIONS: Reverberation and WDRC release time both affect aided consonant identification for individuals with hearing impairment, and these condition effects are associated with alterations to the temporal envelope. There was no significant interaction between reverberation and WDRC release time.

Sexual maturation in the Sumatran rhinoceros (Dicerorhinus sumatrensis).

To help save the Sumatran rhino from extinction, the captive breeding program must capitalize on each rhino's reproductive lifespan. Doing so requires knowing when calves are sexually mature. The goal of this study was to monitor physiological changes associated with sexual maturation in two captive born calves (one male and one female) to determine the approximate age of maturity for both sexes of this species. Fecal testosterone metabolites were monitored in the male calf from 6 months to 7 years of age, and fecal pregnane metabolites were measured in the female calf from 6 months to 5.5 years of age. In addition, rectal ultrasonography was employed to monitor changes in ovarian activity from 2 to 5.5 years of age. The male calf's fecal testosterone concentrations reached levels comparable to those detected in samples from adult males when he was 6-6.5 years of age. The first pre-ovulatory sized follicle was observed on the ovaries of the female calf when she was 4.75 years old, but fecal pregnane metabolite concentrations only reached maximum mean concentrations and variability when she was 5-5.5 years of age. Results from this study indicate that male and female Sumatran rhino calves are sexually mature at 6-6.5 and 5-5.5 years of age, respectively.

Urinalysis in three species of captive rhinoceros (Rhinoceros unicornis, Dicerorhinus sumatrensis, and Diceros bicornis).

This study reports urinalysis values for three species of captive rhinoceros (Rhinoceros unicornis, Dicerorhinus sumatrensis, and Diceros bicornis) and evaluates individual and species differences. Repeated urinalysis was conducted on 11 individuals to establish normal reference ranges. Although no individual or species differences existed in urinary values for pH, all species differed in specific gravity. Rhinoceros urine demonstrated many physical and chemical properties similar to that of the horse, but reliability of this comparison was limited. Urinary pH in the rhinoceros was within range of that established for the horse and other large herbivores. However, all rhinoceros species exhibited urinary specific gravities below the lower limit of the normal equine reference range. Comparative urinalysis using an outside laboratory source confirmed the results of this study and illustrated the value of conducting in-house analysis. These results are the first data available on reference ranges for urine parameters in the greater one-horned, Sumatran, and African black rhinoceros and provide a useful diagnostic tool for the veterinary care of individuals in captivity.

Amelioration of ozone-induced lung injury by anti-tumor necrosis factor-alpha.

Ozone (O(3)) is a significant component of atmospheric air pollution and produces detrimental effects in the lung. Although the mechanism of O(3)-induced lung inflammation and injury is unclear, the increased release of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) by lung cells following O(3) exposure may shed some light on this subject. To investigate the role of TNF-alpha in the O(3)-induced pulmonary insult, we intraperitoneally injected rats with either rabbit preimmune serum or rabbit antirat TNF-alpha 1 h prior to O(3) exposure. Approximately 12 h after the end of O(3) exposure the animals were sacrificed, the lungs lavaged, and tissue samples collected for expression of cytokine genes relevant to inflammation. The bronchoalveolar lavage fluid (BALF) was analyzed for albumin as a marker of pulmonary epithelial permeability changes and for fibronectin for its role in lung injury and repair. The lavage cells were collected, counted, and identified to quantitate the inflammatory response. Ozone exposure resulted in a significant increase in BALF albumin and fibronectin as compared to air-exposed controls and a significant increase in BALF polymorphonuclear leukocytes (PMNs). Antibody treatment produced a significant decrease in BALF albumin and PMNs as compared to O(3)-exposed rats given preimmune serum. Antibody treatment did not affect the BALF fibronectin concentration or the total cell count in the BAL. Tissue analysis for gene arrays revealed an activation of IL-1alpha, IL-6, and IL-10 in animals exposed to O(3). The gene expression was downregulated in animals treated with anti-TNF-alpha antibody prior to O(3) exposure. The results suggest a central role for TNF-alpha in the mechanistic pathways critical to lung inflammation. The significance of TNF-alpha in the inflammation and epithelial injury produced by ozone exposure reflects its overall contribution through modulation of other cytokines.