Vowel identification by cochlear implant users: Contributions of duration cues and dynamic spectral cues.

A recent study from our laboratory assessed vowel identification in cochlear implant (CI) users, using full /dVd/ syllables and partial (center- and edges-only) syllables with duration cues neutralized [Donaldson, Rogers, Cardenas, Russell, and Hanna (2013). J. Acoust. Soc. Am. 134, 3021-3028]. CI users' poorer performance for partial syllables as compared to full syllables, and for edges-only syllables as compared to center-only syllables, led to the hypotheses (1) that CI users may rely strongly on vowel duration cues; and (2) that CI users have more limited access to dynamic spectral cues than steady-state spectral cues. The present study tested those hypotheses. Ten CI users and ten young normal hearing (YNH) listeners heard full /dVd/ syllables and modified (center- and edges-only) syllables in which vowel duration cues were either preserved or eliminated. The presence of duration cues significantly improved vowel identification scores in four CI users, suggesting a strong reliance on duration cues. Duration effects were absent for the other CI users and the YNH listeners. On average, CI users and YNH listeners demonstrated similar performance for center-only stimuli and edges-only stimuli having the same total duration of vowel information. However, three CI users demonstrated significantly poorer performance for the edges-only stimuli, indicating apparent deficits of dynamic spectral processing.

Vowel identification by cochlear implant users: contributions of static and dynamic spectral cues.

Previous research has shown that normal hearing listeners can identify vowels in syllables on the basis of either quasi-static or dynamic spectral cues; however, it is not known how well cochlear implant (CI) users with current-generation devices can make use of these cues. The present study assessed vowel identification in adult CI users and a comparison group of young normal hearing (YNH) listeners. Stimuli were naturally spoken /dVd/ syllables and modified syllables that retained only quasi-static spectral cues from an 80-ms segment of the vowel center ("C80" stimuli) or dynamic spectral cues from two 20-ms segments of the vowel edges ("E20" stimuli). YNH listeners exhibited near-perfect performance for the unmodified (99.8%) and C80 (92.9%) stimuli and maintained good performance for the E20 stimuli (70.2%). CI users exhibited poorer average performance than YNH listeners for the Full stimuli (72.3%) and proportionally larger reductions in performance for the C80 stimuli (41.8%) and E20 stimuli (29.0%). Findings suggest that CI users have difficulty identifying vowels on the basis of spectral cues in the absence of duration cues, and have limited access to brief dynamic spectral cues. Error analyses suggest that CI users may rely strongly on vowel duration cues when those cues are available.

Development and evaluation of a high-fidelity canine patient simulator for veterinary clinical training.

High-fidelity human patient simulators have been used for decades in medical education to provide opportunities for students to practice technical skills, diagnostic and therapeutic planning, and communication skills in a safe environment. A high-fidelity canine patient simulator (CPS) was developed using components from a human patient simulator and a low-fidelity foam core canine mannequin. Ninety-six veterinary students participated in cardiopulmonary arrest scenarios in groups of three to five students. Afterwards, participants were asked to complete an anonymous online survey describing their experiences. A total of 70 students (73%) completed the survey. All of the students (100%) felt that the simulator session expanded their cardiopulmonary resuscitation (CPR) knowledge base, and 97% responded that their skills and abilities had improved. Students also expressed positive opinions about the CPS, with 89% agreeing or strongly agreeing that the CPS was realistic and 73% agreeing or strongly agreeing that the scenarios generated emotions similar to real clinical situations. Most participants (98.5%) agreed or strongly agreed that the simulator was an engaging learning experience. Students commonly commented that the simulations allowed them to practice communication and teamwork skills and were more effective than paper-based, problem-oriented learning opportunities and lecture. Students also commented that they wanted more opportunities to participate in simulation exercises. These results suggest that high-fidelity veterinary simulation is an engaging educational methodology that addresses some limitations of other forms of problem-based learning. More studies are needed to quantitatively determine the effectiveness of this novel veterinary educational technology in comparison with more traditional approaches.

Abdominal aortic aneurysm associated with systemic fungal infection in a German shepherd dog.

A 2 yr old spayed female German shepherd presented with a chief complaint of acute onset paraparesis and weight loss. At presentation, the dog was pyrexic, nonambulatory, and had generalized muscle wasting. Neurolocalization was consistent with a thoracolumbar spinal cord lesion. An abdominal ultrasound was performed and revealed a focal dilation (4 cm) of the terminal aorta with evidence of blood stasis consistent with an aortic aneurysm. The dog was euthanized shortly after admission to the hospital and a post mortem examination was performed. Fungal organisms were identified in the aortic aneurysm as well as from the thoracic vertebrae, mesenteric lymph nodes, axillary lymph nodes, spleen, kidneys, liver, lungs, and heart. Although the morphology was consistent with Candida spp., immunohistochemistry and PCR could not definitively identify the causative organism. Mycotic aortic aneurysms are a rare finding in humans and have not been previously reported in the dog. To the authors' knowledge, this is the first known report of an aortic aneurysm associated with systemic fungal infection in a dog.

Vowel identification by younger and older listeners: relative effectiveness of vowel edges and vowel centers.

Young normal-hearing (YNH) and older normal-hearing (ONH) listeners identified vowels in naturally produced /bVb/ syllables and in modified syllables that consisted of variable portions of the vowel edges (silent-center [SC] stimuli) or vowel center (center-only [CO] stimuli). Listeners achieved high levels of performance for all but the shortest stimuli, indicating that they were able to access vowel cues throughout the syllable. ONH listeners performed similarly to YNH listeners for most stimuli, but performed more poorly for the shortest CO stimuli. SC and CO stimuli were equally effective in supporting vowel identification except when acoustic information was limited to 20 ms.

Conversational and clear speech intelligibility of /bVd/ syllables produced by native and non-native English speakers.

The ability of native and non-native speakers to enhance intelligibility of target vowels by speaking clearly was compared across three talker groups: monolingual English speakers and native Spanish speakers with either an earlier or a later age of immersion in an English-speaking environment. Talkers produced the target syllables "bead, bid, bayed, bed, bad" and "bod" in 'conversational' and clear speech styles. The stimuli were presented to native English-speaking listeners in multi-talker babble with signal-to-noise ratios of -8 dB for the monolingual and early learners and -4 dB for the later learners. The monolinguals and early learners of English showed a similar average clear speech benefit, and the early learners showed equal or greater intelligibility than monolinguals for most target vowels. The 4-dB difference in signal-to-noise ratio yielded approximately equal average intelligibility for the monolinguals and later learners. The average clear speech benefit was smallest for the later learners, and a significant clear speech decrement was obtained for the target syllable "bid." These results suggest that later learners of English as a second language may be less able than monolinguals to accommodate listeners in noisy environments, due to a reduced ability to improve intelligibility by speaking more clearly.

Disseminated candidiasis secondary to fungal and bacterial peritonitis in a young dog.

OBJECTIVE: To describe a severe case of bacterial sepsis and disseminated candidiasis in a previously healthy dog. CASE SUMMARY: Fungal sepsis was identified in a 2-year-old dog following intestinal dehiscence 4 days after abdominal surgery. Septic peritonitis was identified at admission and evidence of dehiscence at the previous enterotomy site was found during an exploratory laparotomy. Both gram-positive cocci and Candida albicans were cultured from the abdominal cavity. Candida sp. was also subsequently cultured from a central venous catheter. Euthanasia was performed due to failure to respond to therapy. Fungal organisms, morphologically consistent with Candida spp., were found in the lungs and kidney on postmortem histopathologic examination indicating disseminated candidiasis. NEW OR UNIQUE INFORMATION PROVIDED: Candida peritonitis is a well-recognized entity in humans and contributes to morbidity and mortality in critically ill patients. Abdominal surgery, intestinal perforation, presence of central venous catheters, and administration of broad-spectrum antibiotics are all considered to be suspected risk factors. This report describes the first known case of systemic candidiasis occurring secondary to Candida peritonitis and bacterial sepsis in a critically ill dog.

Perception of silent-center syllables by native and non-native English speakers.

The amount of acoustic information that native and non-native listeners need for syllable identification was investigated by comparing the performance of monolingual English speakers and native Spanish speakers with either an earlier or a later age of immersion in an English-speaking environment. Duration-preserved silent-center syllables retaining 10, 20, 30, or 40 ms of the consonant-vowel and vowel-consonant transitions were created for the target vowels /i, I, eI, epsilon, ae/ and /a/, spoken by two males in /bVb/ context. Duration-neutral syllables were created by editing the silent portion to equate the duration of all vowels. Listeners identified the syllables in a six-alternative forced-choice task. The earlier learners identified the whole-word and 40 ms duration-preserved syllables as accurately as the monolingual listeners, but identified the silent-center syllables significantly less accurately overall. Only the monolingual listener group identified syllables significantly more accurately in the duration-preserved than in the duration-neutral condition, suggesting that the non-native listeners were unable to recover from the syllable disruption sufficiently to access the duration cues in the silent-center syllables. This effect was most pronounced for the later learners, who also showed the most vowel confusions and the greatest decrease in performance from the whole word to the 40 ms transition condition.

An adaptive clinical test of temporal resolution.

PURPOSE: It has been recommended that diagnostic and screening test batteries for auditory processing disorder (APD) include a measure of temporal gap detection using broadband noise stimuli. Although psychophysical laboratory procedures exist for the measurement of temporal resolution, none are clinically feasible. This study was designed to obtain preliminary data on a new clinical measure of gap detection, the Adaptive Test of Temporal Resolution (ATTR). METHOD: The ATTR, a currently available clinical test (Random Gap Detection Test), and a standard psychophysical laboratory procedure were used to measure gap detection thresholds (GDTs) from a group of 30 young adults with normal hearing. RESULTS: Mean ATTR GDTs were 2.2 ms, consistent with GDTs measured using the psychophysical laboratory procedure (3.2 ms) and significantly smaller than those measured using the Random Gap Detection Test (7.0 ms). CONCLUSIONS: Because it incorporates standard adaptive psychophysical methodology in a computer application that can be used on any desktop computer but does not depend on specialized hardware for application, the ATTR promises to be a clinically feasible addition to the APD test battery.

Forced-choice analysis of segmental production by Chinese-accented English speakers.

This study describes the development of a minimal-pairs word list targeting phoneme contrasts that pose difficulty for Mandarin Chinese-speaking learners of English as a second language. The target phoneme inventory was compiled from analysis of phonetic transcriptions of about 800 mono- and polysyllabic English words with examples of all the vowels, diphthongs, and syllable onsets and codas of the language. The Mandarin-specific minimal-pairs list derived from the phonetic transcription analyses contains 190 items. Tape recordings were made of 8 Mandarin speakers reading a randomized version of target items from the minimal-pairs list and a set of 20 sentences. Listeners who were native American English speakers judged the words in a forced-choice task and wrote down what they understood of the sentences. Correlations between listener responses on the forced-choice task and the sentence intelligibility scores showed differences in the strength of the relationship with sentence intelligibility across categories of minimal-pairs contrasts. Multiple regression analysis found listener responses on the minimal-pairs task to account for approximately 76% of the variance in speakers' sentence intelligibility scores, showing that performance on the minimal pairs of the probe list does predict connected speech intelligibility. Analyses of individual contrasts indicate target phonemes most often misperceived by native listeners.

Effects of noise and proficiency on intelligibility of Chinese-accented English.

This study compared the intelligibility of native and foreign-accented bilingualism English speech presented in quiet and mixed with three different levels of background noise. Two native American English speakers and four native Mandarin Chinese speakers for whom English is a second language each read a list of 50 phonetically balanced sentences (Egan, 1948). The authors speech intelligibility identified two of the Mandarin-accented English speakers as high-proficiency speakers and two as lower proficiency speakers, based on their speech intelligibility in quiet (about 95% and 80%, respectively). Original record-perception ings and noise-masked versions of 48 utterances were presented to monolingual American English speakers. Listeners were asked to write down the words they heard the speakers say, and intelligibility was measured as content words correctly identified. While there was a modest difference between native and high-proficiency speech in quiet (about 7%), it was found that adding noise to the signal reduced the intelligibility of high-proficiency accented speech significantly more than it reduced the intelligibility of native speech. Differences between the two groups in the three added noise conditions ranged from about 12% to 33%. This result suggests that even high-proficiency non-native speech is less robust than native speech when it is presented to listeners under suboptimal conditions.

Final consonant discrimination in children: effects of phonological disorder, vocabulary size, and articulatory accuracy.

Preschool-age children with phonological disorders were compared to their typically developing age peers on their ability to discriminate CVC words that differed only in the identity of the final consonant in whole-word and gated conditions. The performance of three age groups of typically developing children and adults was also assessed on the same task. Children with phonological disorders performed more poorly than age-matched peers, and younger typically developing children performed more poorly than older children and adults, even when the entire CVC word was presented. Performance in the whole-word condition was correlated with receptive vocabulary size and a measure of articulatory accuracy across all children. These results suggest that there is a complex relationship among word learning skills, the ability to attend to fine phonetic detail, and the acquisition of articulatory-acoustic and acoustic-auditory representations.