Research News in Speech,
Language, and Hearing Disorders
for January 2007

January 5, 2006

• Categorical Perception of Speech (VOT) and Analogous Non-Speech (FOT) Signals: Behavioral and Electrophysiological Correlates
  from the current issue of Ear and Hearing
  "Objective: To determine whether voicing perception is influenced primarily by linguistic experience or if it is due to innate temporal sensitivity to voicing boundaries, by examining behavioral and electrophysiological correlates of speech Voice-Onset-Time (VOT) and nonspeech Formant-Onset-Time (FOT) categorical perception. Design: Behavioral measures and auditory event-related potentials (ERPs) were obtained from 14 normal-hearing Hebrew speakers, whose voicing distinction is different than English, during identification and discrimination of two sets of stimuli: a VOT continuum, created by editing natural productions of /ba/ and /pa/, and an analogous nonspeech continuum, composed of two synthesized formants, varying in their onset time-FOT. Results: VOT and FOT continua yielded similar behavioral identification curves. Differences between the two stimulus types were found in discrimination of within-category differences and in reaction time effects. During identification and discrimination tasks, ERPs were differently affected by the VOT or FOT value of the stimulus: VOT value had a significant effect on N1 latency and on N1 and P2 amplitudes whereas FOT value had a significant effect on P2 amplitude. Additionally, during identification tasks, whereas all speech signals evoked a P3, regardless of overt categorization, only the perceptually "rare" nonspeech stimulus (+15 msec FOT) evoked a P3. Conclusions: Voicing boundaries corresponded to Hebrew VOT values of production, suggesting that voicing perception in Hebrew is mediated mainly by linguistic experience rather than by innate temporal sensitivity. ERP data differed to VOT versus FOT stimuli as early as N1, indicating that brain processing of the temporal aspects of speech and nonspeech signals differ from their early stages. Further studies to establish the neural response patterns to voicing in speakers of languages that use different voicing categories than English are warranted."

• Effects of Bone Oscillator Coupling Method, Placement Location, and Occlusion on Bone-Conduction Auditory Steady-State Responses in Infants
  o from the current issue of Ear and Hearing
  "Objective: The aim of these experiments was to investigate procedures used when estimating bone-conduction thresholds in infants. The objectives were: (i) to investigate the variability in force applied using two common bone-oscillator coupling methods and to determine whether coupling method affects threshold estimation, (ii) to examine effects of bone-oscillator placement on bone-conduction ASSR thresholds, and (iii) to determine whether the occlusion effect is present in infants by comparing bone-conduction ASSR thresholds for unoccluded and occluded ears. Design: Experiment 1A: The variability in the amount of force applied to the bone oscillator by trained assistants (n = 4) for elastic-band and hand-held coupling methods was measured. Experiment 1B: Bone-conduction behavioral thresholds in 10 adults were compared for two coupling methods. Experiment 1C: ASSR thresholds and amplitudes to multiple bone-conduction stimuli were compared in 10 infants (mean age: 17 wk) using two coupling methods. Experiment 2: Bone-conduction ASSR thresholds and amplitudes were compared for temporal, mastoid and forehead oscillator placements in 15 preterm infants (mean age: 35 wk postconceptual age (PCA)). Experiment 3: Bone-conduction ASSR thresholds, amplitudes and phase delays were compared in 13 infants (mean age: 15 wk) for an unoccluded and occluded test ear. All infants that participated had passed a hearing screening test. Results: Experiment 1A: Coupling method did not significantly affect the variability in force applied to the oscillator. Experiment 1B: There were no differences in adult bone-conduction behavioural thresholds between coupling methods. Experiment 1C: There was no significant difference between oscillator coupling method or significant frequency x coupling method interaction for ASSR thresholds or amplitudes in the young infants tested. However, there was a nonsignificant 9-dB better threshold at 4000 Hz for the elastic-band method. Experiment 2: Mean bone-conduction ASSR thresholds for the preterm infants were not significantly different for the temporal and mastoid placements. Mean ASSR thresholds for the forehead placement were significantly higher compared to the other two placements (12-18 dB higher on average). Mean ASSR amplitudes were significantly larger for the temporal and mastoid placements compared to the forehead placement. Experiment 3: There was no difference in mean ASSR thresholds, amplitudes or phase delays for the unoccluded versus occluded conditions. Conclusions: Trained assistants can apply an appropriate amount of force to the bone oscillator using either the elastic-band or hand-held method. Coupling method has no significant effect on estimation of bone-conduction thresholds; therefore, either may be used clinically provided assistants are appropriately trained. For preterm infants, there are no differences in ASSRs when the oscillator is positioned at the temporal or mastoid placement. However, thresholds are higher and amplitudes are smaller for the forehead placement, consequently, a forehead placement should be avoided for clinical testing. There does not appear to be a significant occlusion effect in young infants; therefore, it may be possible to do bone-conduction testing with ears unoccluded or occluded without applying a correction factor, although further research is needed to confirm this finding."

• Estimates of Basilar-Membrane Nonlinearity Effects on Masking of Tones and Speech
  from the current issue of Ear and Hearing
  "Objective: The aim of this experiment was to assess the contribution of cochlear nonlinearities to speech recognition in noise for individuals with normal hearing and a range of quiet thresholds. For signals close to the characteristic frequency (CF) of a place on the basilar membrane, the normal growth of response of the basilar membrane is linear at lower signal levels and compressed at medium to higher signal levels. In contrast, at moderate to high CFs, the basilar membrane responds more linearly to stimuli at frequencies well below the CF regardless of input level. Thus, for moderate-level speech and a lower frequency masker, the response to the masker grows linearly whereas the response to the speech is compressed, which may result in changes in the effectiveness of the masker on speech recognition with increases in masker level. To test this hypothesis, observed speech-recognition scores were compared with scores predicted using an audibility-based model, which did not include nonlinear effects that may influence masker effectiveness. Design: Growth of simultaneous masking was measured for moderate-level bandpass-filtered nonsense syllables and for 350-msec pure tones at frequencies within the speech passband. Masker frequencies were within (on-frequency) or below (off-frequency) the speech passband. Estimates of basilar-membrane nonlinearities were derived from growth-of-masking functions for 10-msec, 2.0- and 4.0-kHz tones in narrowband, off-frequency maskers presented simultaneously. Subjects were 26 adults with normal hearing with approximately a 20-dB range of average quiet thresholds. Results: Breakpoints (i.e., the levels corresponding to the transitions from linear to nonlinear responses) were strongly associated with quiet thresholds but slopes measured above the breakpoints were independent of quiet thresholds. Individual differences were substantially larger for off-frequency masking of pure tones and speech than for on-frequency masking of pure tones and speech. Using an audibility-based predictive model, the change in speech audibility resulting from the compressed response to speech with increasing off-frequency masker level (and the resulting decline in scores) was well predicted from nonlinear growth of masking for pure tones measured in the same off-frequency masker. However, absolute speech-recognition predictions were generally inaccurate and were a function of how well pure-tone signal levels at masked threshold estimated masker effectiveness for speech. That is, subjects with lower off-frequency masked thresholds had less accurate predictions of speech recognition in off-frequency maskers. Conclusions: Large individual differences in off-frequency masking of pure tones and speech are consistent with the assumption that small changes in the shape of the basilar-membrane input-output function result in large changes in the amount of off-frequency masking but small (if any) changes in on-frequency masking where the signal and masker are subject to a similar compression. Growth of off-frequency masking of pure tones and speech were correlated with each other, consistent with the underlying basilar-membrane response, and consistent with changes in breakpoints for subjects with normal hearing and a range of quiet thresholds. These results provide support for a role of nonlinear effects in the understanding of speech in noise."

• Evaluation of the Benefit for Cochlear Implantees of Two Assistive Directional Microphone Systems in an Artificial Diffuse Noise Situation
  from the current issue of Ear and Hearing
  "Objective: People with cochlear implants have severe problems with speech understanding in noisy surroundings. This study evaluates and quantifies the effect of two assistive directional microphone systems compared to the standard headpiece microphone on speech perception in quiet surroundings and in background noise, in a laboratory setting developed to reflect a situation whereby the listener is disturbed by a noise with a mainly diffuse character due to many sources in a reverberant room. Design: Thirteen postlingually deafened patients, implanted in the Leiden University Medical Centre with the Clarion CII device, participated in the study. An experimental set-up with 8 uncorrelated steady-state noise sources was used to test speech perception on monosyllabic words. Each subject was tested with a standard headpiece microphone, and the two assistive directional microphones, TX3 Handymic by Phonak and the Linkit array microphone by Etymotic Research. Testing was done in quiet at a level of 65 dB SPL and with decreasing signal-to-noise ratios (SNR) down to -15 dB. Results: Using the assistive directional microphones, speech recognition in background noise improved substantially and was not affected in quiet. At an SNR of 0 dB, the average CVC scores improved from 45% for the headpiece microphone to 67% and 62% for the TX3 Handymic and the Linkit respectively. Compared to the headpiece, the Speech Reception Threshold (SRT) improved by 8.2 dB SNR and 5.9 dB SNR for the TX3 Handymic and the Linkit respectively. The gain in SRT for TX3 Handymic and Linkit was neither correlated to the SRT score with headpiece nor the duration of CI-use. Conclusion: The speech recognition test in background noise showed a clear benefit from the assistive directional microphones for cochlear implantees compared to the standard microphone. In a noisy environment, the significant benefit from these assistive device microphones may allow understanding of speech with greater ease."

• Mitochondrial rRNA and tRNA and hearing function
  from the current issue of Cell Research
  "The human ear is a delicate sensory apparatus of hearing for normal communication, and its proper functioning is highly dependent on mitochondrial oxidative phosphorylation. The first mitochondrial point mutation for nonsyndromic and aminoglycoside-induced hearing loss was identified in 1993. Since then a number of inherited mitochondrial mutations have been implicated in hearing loss. Most of the molecular defects responsible for mitochondrial disorder-associated hearing loss are mutations in the 12S rRNA gene and tRNA genes. In this review, after a short description of normal hearing mechanisms and mitochondrial genetics, we outline the recent advances that have been made in the identification of deafness-associated mitochondrial mutations, and discuss how mitochondrial dysfunction contributes to hearing loss."

• Predictive Measures of Directional Benefit Part 1: Estimating the Directivity Index on a Manikin
  from the current issue of Ear and Hearing
  "Objective: In this investigation, a method for computing a directivity index (DI) on a manikin for directional microphones in hearing aids was proposed and evaluated comparatively to other conventional methods. Design: Test devices included first- and second-order directional microphones. Signal presentation, implemented in an anechoic chamber, involved a single noise source rotated completely around the directional microphone in a hearing aid, in free field and on a manikin, at a defined radius. The area covered was equivalent to the approximate surface area of a sphere. It was anticipated that an equal angular resolution of 10[degrees] (elevation and azimuth) would effectively estimate the DI of first-, second-, and higher-order directional microphone systems located in a hearing aid on a manikin. A total of 450 spatially varied presentation points were analyzed, each weighted in reference to direction of arrival on the directional microphone. Results: Empiric differences between the DI derived from the 3D-DI method proposed in this investigation and the conventionally derived 2D-DI method DI on a manikin were as large as 3.8 dB in the higher frequencies, depending on the device under test. Conclusions: The magnitude of these differences was dependent on the device under test microphone location. The further the microphone was placed into the ear of the manikin, the larger the empiric differences."

• Predictive Measures of Directional Benefit Part 2: Verification of Different Approaches to Estimating Directional Benefit
  from the current issue of Ear and Hearing
  "Objective: In this investigation, the relation between various directivity measures and subject performance with directional microphone hearing aids was determined. Design: Test devices included first- and second-order directional microphones. Recordings of sentences and noise (Hearing in Noise Test, HINT) were made through each test device in simple, complex, and anisotropic background noise conditions. Twenty-six subjects, with normal hearing, were administered the HINT test recordings and directional benefit was computed. These measures were correlated to theoretical, free-field, and Knowles Electronic Manikin for Acoustic Research (KEMAR) directivity index (DI) values, as well as front-to-back ratios (FBR), in situ signal-to-noise ratios (SNR), and a newly proposed Db SNR, wherein a predictive value of the SNR improvement is calculated as a function of the noise source incidence. Results: The different predictive scores showed high correlation to the measured directional benefit scores in the complex (diffuse-like) background noise condition (r = 0.89 to 0.97, p < 0.05) but not across all background noise conditions (r = 0.45 to 0.97, p < 0.05). The Db SNR approach and the in situ SNR measures provided excellent prediction of subject performance in all background noise conditions (0.85 to 0.97, p < 0.05). None of the predictive measures could account for the effects of reverberation on the speech signal (r = 0.35 to 0.40, p < 0.05). Conclusions: For environments that included a discrete number of noise sources, the in situ SNR and Db SNR estimates were most predictive of subject performance. No predictive approach was indicative of the directional benefit achieved when the speech was also subjected to reverberation (temporal distortion). This finding has implications for real-world estimates of directional benefit."

• Sound-Direction Identification with Bilateral Cochlear Implants
  from the current issue of Ear and Hearing
  "Objective: The purpose of this study was to compare the accuracy of sound-direction identification in the horizontal plane by bilateral cochlear implant users when localization was measured with pink noise and with speech stimuli. Design: Eight adults who were bilateral users of Nucleus 24 Contour devices participated in the study. All had received implants in both ears in a single surgery. Sound-direction identification was measured in a large classroom by using a nine-loudspeaker array. Localization was tested in three listening conditions (bilateral cochlear implants, left cochlear implant, and right cochlear implant), using two different stimuli (a speech stimulus and pink noise bursts) in a repeated-measures design. Results: Sound-direction identification accuracy was significantly better when using two implants than when using a single implant. The mean root-mean-square error was 29[degrees] for the bilateral condition, 54[degrees] for the left cochlear implant, and 46.5[degrees] for the right cochlear implant condition. Unilateral accuracy was similar for right cochlear implant and left cochlear implant performance. Sound-direction identification performance was similar for speech and pink noise stimuli. Conclusions: The data obtained in this study add to the growing body of evidence that sound-direction identification with bilateral cochlear implants is better than with a single implant. The similarity in localization performance obtained with the speech and pink noise supports the use of either stimulus for measuring sound-direction identification."

• Speech Understanding in Background Noise with the Two-Microphone Adaptive Beamformer BEAM[TM] in the Nucleus Freedom[TM] Cochlear Implant System
  from the current issue of Ear and Hearing
  "Objective: This paper evaluates the benefit of the two-microphone adaptive beamformer BEAM[TM] in the Nucleus Freedom[TM] cochlear implant (CI) system for speech understanding in background noise by CI users. Design: A double-blind evaluation of the two-microphone adaptive beamformer BEAM and a hardware directional microphone was carried out with five adult Nucleus CI users. The test procedure consisted of a pre- and post-test in the lab and a 2-wk trial period at home. In the pre- and post-test, the speech reception threshold (SRT) with sentences and the percentage correct phoneme scores for CVC words were measured in quiet and background noise at different signal-to-noise ratios. Performance was assessed for two different noise configurations (with a single noise source and with three noise sources) and two different noise materials (stationary speech-weighted noise and multitalker babble). During the 2-wk trial period at home, the CI users evaluated the noise reduction performance in different listening conditions by means of the SSQ questionnaire. In addition to the perceptual evaluation, the noise reduction performance of the beamformer was measured physically as a function of the direction of the noise source. Results: Significant improvements of both the SRT in noise (average improvement of 5-16 dB) and the percentage correct phoneme scores (average improvement of 10-41%) were observed with BEAM compared to the standard hardware directional microphone. In addition, the SSQ questionnaire and subjective evaluation in controlled and real-life scenarios suggested a possible preference for the beamformer in noisy environments. Conclusions: The evaluation demonstrates that the adaptive noise reduction algorithm BEAM in the Nucleus Freedom CI-system may significantly increase the speech perception by cochlear implantees in noisy listening conditions. This is the first monolateral (adaptive) noise reduction strategy actually implemented in a mainstream commercial CI."

January 4, 2007

• Associative Symmetry Versus Independent Associations in the Memory for Object-Location Associations.
  from the current issue of the Journal of Experimental Psychology: Learning, Memory, and Cognition
  "The formation of associations between objects and locations is a vital aspect of episodic memory. More specifically, remembering the location where one experienced an object and, vice versa, the object one encountered at a specific location are both important elements for the memory of an event. Whether episodic associations are holistic representations of individual components or whether there are unidirectional, separately modifiable connections between them has been investigated nearly exclusively using verbal stimuli. A preliminary conclusion concerning this controversy is that verbal associations are, at least, highly correlated (M. J. Kahana, 2002). This theoretical debate, which in the past has undergone a major empirical effort, is still of relevance for the concurrent global matching models of associative memory (S. E. Clark & S. D. Gronlund, 1996). The authors used variations of a novel object-location learning paradigm to complement the accumulated evidence regarding the nature of episodic associations. (PsycINFO Database Record (c) 2007 APA, all rights reserved)"

• Cochlear Cytokine Gene Expression in Murine Acute Otitis Media
  from the current issue of Laryngoscope
  "Objective: Recurrent acute otitis media (AOM) causes sensorineural hearing loss by unknown mechanisms. It is widely accepted that inflammatory cytokines diffuse across the round window membrane to exert cytotoxic effects. This study addresses whether inner ear cells are capable of expressing genes for inflammatory cytokines. Study Design: The authors conducted a prospective animal study. Methods: BALB/C mice underwent transtympanic injection of heat-killed Haemophilus influenzae to create an acute inflammatory response. These mice were compared with a control group in addition to a group of uninjected mice found to have otomicroscopic changes consistent with persistent or chronic otitis media. The cochleas of these mice were obtained, their RNA harvested, and cytokine gene expression analyzed using prefabricated cDNA arrays. Results: Four groups of mice (control, 3-day postinjection, 7-day postinjection, and mice with chronic otitis media) with five mice in each group were analyzed. Numerous classes of genes were found to be upregulated or downregulated by more than twofold. Some genes differed from control mice by more than 10-fold. These genes included numerous fibroblast growth factors, interleukins, tumor necrosis factors, and colony-stimulating factors. Conclusion: The genes of numerous inflammatory cytokines are either up- or downregulated by murine inner ear cells in response to either acute or chronic inflammation of the middle ear. This study provides a novel site of production of cytokines that may be responsible for the damage seen in sensorineural hearing loss."

• Early Swallowing Problems in a Cohort of Patients With Nasopharyngeal Carcinoma: Symptomatology and Videofluoroscopic Findings
  from the current issue of Laryngoscope
  "Objective: To study the incidence and the degree of swallowing dysfunction in patients with nasopharyngeal carcinoma (NPC) who underwent radiation therapy treatment. Institution: The study was conducted in the Prince of Wales Hospital, a tertiary teaching hospital of the Chinese University of Hong Kong. Materials and Methods: From October 1999 to July 2001, a cohort of 20 consecutive patients with newly diagnosed NPC was prospectively studied. Questions about symptoms, including swallowing functions, were asked, and head and neck examination including oromotor examination was performed in the subjects before radiation therapy. All patients were subjected to videofluoroscopy (VFSS) to assess their swallowing function. Abnormalities were scored if they were present on two of three swallow attempts. The patients were reassessed at 6 months and 12 months after radiotherapy by symptom assessment and VFSS. Results: There were 14 male and 6 female patients. The mean age was 43.9 years. Nine patients had early (stage I and II) disease, whereas 11 patients had advanced (stage III and IV) disease. Nine patients were treated by radiation therapy only and 11 patients by concurrent chemoirradiation. Ninety-five percent of the subjects had subjective dysphagia at 6 and 12 months after radiation therapy. Ninety percent had xerostomia, and 80% had to avoid certain foods at 12 months postradiation therapy. All subjects had to alternate solid food with fluid intake to facilitate swallowing. An average reduction of jaw movement by 1 cm was noted. A large proportion of patients had stasis of food in the pharynx (100% in valleculae and 60% in pyriform fossae) and impaired pharyngeal peristalsis (60%). One quarter of patients had laryngeal penetration. Conclusions: Subjective swallowing difficulties were common in patients in the early follow-up period after radiation therapy for NPC according to questionnaire assessment. An objective swallowing study revealed that swallowing dysfunction was persistent 12 months after radiation therapy."

• Event-Related Potential Indicators of Text Integration Across Sentence Boundaries
  from the current issue of the Journal of Experimental Psychology: Learning, Memory, and Cognition
  "An event-related potentials (ERPs) study examined word-to-text integration processes across sentence boundaries. In a two-sentence passage, the accessibility of a referent for the first content word of the second sentence (the target word) was varied by the wording of the first sentence in one of the following ways: lexically (explicitly using a form of the target word); conceptually (using a paraphrase of the target word), and situationally (encouraging an inference concerning the referent of the target word). A baseline condition had no coreference between the two sentences. ERP results on the target word indicated multiple effects related to word identification and word-to-referent mapping processes. Both the explicit and paraphrase conditions, but not the inference condition, showed a reduced N400 relative to the baseline condition, consistent with immediate integration by lexico-semantic processes. A 300-ms effect (P300) was found in the paraphrase condition. The results were consistent with an immediate integration hypothesis and furthermore differentiated a lexical (N200), a conceptual (P300), and a situational (N400) component for this integration. The conceptual basis appears not to extend to predictive inferences. (PsycINFO Database Record (c) 2007 APA, all rights reserved)"

• Impact of Intrascalar Blood on Hearing
  from the current issue of Laryngoscope
  "Objective/Hypothesis: The objective of this controlled animal study was to evaluate the effects of intrascalar blood on hearing. Material and Methods: Eight guinea pigs underwent intrascalar administration of their own blood in one ear and control solution in the contralateral ear. Solutions were applied through cochleostomy to the scala tympani. Compound action potential (CAP) thresholds were determined before administration and at different intervals for 2 months thereafter. Results: Immediate deterioration of thresholds was seen mainly in the high-frequency range, averaging 27 dB and 20 dB in the study and control groups, respectively. At day 3, threshold shifts recovered in the control group but remained in the low-frequency range in the study group. An extensive recovery was seen in both groups. However, permanent threshold shifts persisted. There was an enhanced shift of thresholds of up to 7 dB in the study group. Conclusions: Even small amounts of intrascalar blood seem to cause transient and permanent detrimental effects on cochlear function. In procedures involving opening of the otic capsule-like stapes surgery and cochlear implantation with hearing preservation-minimizing surgical blood admixture to intracochlear compartments seems therefore fundamental."

• Intratympanic Dexamethasone for Sudden Sensorineural Hearing Loss After Failure of Systemic Therapy
  from the current issue of Laryngoscope
  "Objective: Intratympanic steroids are increasingly used in the treatment of inner ear disorders, especially in patients with sudden sensorineural hearing loss (SNHL) who have failed systemic therapy. We reviewed our experience with intratympanic steroids in the treatment of patients with sudden SNHL to determine overall success, morbidity, and prognostic factors. Hypothesis: Intratympanic steroids have minimal morbidity and the potential to have a positive effect on hearing recovery in patients with sudden SNHL who have failed systemic therapy. Study Design: The authors conducted a retrospective review. Methods: Patients presenting with sudden SNHL defined as a rapid decline in hearing over 3 days or less affecting 3 or more frequencies by 30 dB or greater who underwent intratympanic steroids therapy (24 mg/mL dexamethasone) were reviewed. Excluded were patients with Meniere disease, retrocochlear disease, autoimmune HL, trauma, fluctuating HL, radiation-induced HL, noise-induced HL, or any other identifiable etiology for sudden HL. Patients who showed signs of fluctuation of hearing after injection were excluded. Pretreatment and posttreatment audiometric evaluations including pure-tone average (PTA) and speech reception threshold (SRT) were analyzed. Patient variables as they related to recovery were studied and included patient age, time to onset of therapy, status of the contralateral ear, presence of diabetes, severity of HL, and presence of associated symptoms (tinnitus, vertigo). A 20-dB gain in PTA or a 20% improvement in SDS was considered significant. Results: Forty patients fit the criteria for inclusion in the study. The mean age of the patients was 54.8 years with a range from 17 to 84 years of age. Overall, 40% (n = 16) showed any improvement in PTA or SDS. Fourteen (35%) men and 26 (65%) women were included. Using the criteria of 20-dB improvement in PTA or 20% improvement in SDS for success, 27.5% (n = 11) showed improvement. The mean number of days from onset of symptoms to intratympanic therapy was 40 days with a range of 7 days to 310 days. A statistically significant difference was noted in those patients who received earlier injection (P = .0008, rank sum test). No patient receiving intratympanic dexamethasone after 36 days recovered hearing using 20-dB PTA decrease or a 20% increase in discrimination as criteria for recovery. Twelve percent (n = 5) of patients in the study had diabetes with 20% recovering after intratympanic dexamethasone (not significantly different from nondiabetics at 28.6%, Fisher exact test, P = 1.0). Comparison to other studies that used differing steroid type, concentration, dosing schedule, inclusion criteria, and criteria for success revealed, in many instances, a similar overall recovery rate. Conclusions: Difficulty in proving efficacy of a single modality is present in all studies on SNHL secondary to multiple treatment protocols, variable rates of recovery, and a high rate of spontaneous recovery. Forty percent of patients showed some improvement in SDS or PTA after treatment failure. When criteria of 20-dB PTA or 20% is considered to define improvement, the recovery rate was 27.5%. Modest improvement is seen with the current protocol of a single intratympanic steroid injection of 24 mg/mL dexamethasone in patients who failed systemic therapy. Dramatic hearing recovery in treatment failures was rarely encountered. No patient showed significant benefit from intratympanic steroids after 36 days when using this protocol for idiopathic sudden SNHL. If patients injected after 6 weeks are excluded from the study, the improvement rate increases from 26.9% to 39.3%. Earlier intratympanic injection had a significant impact on hearing recovery, although with any therapeutic intervention for sudden SNHL, early success may be attributed to natural history. If we further exclude seven patients treated with intratympanic steroids within 2 weeks of the onset of symptoms (i.e., study only those patients treated with intratympanic dexamethasone between 2 and 6 weeks after onset of symptoms), still, 26% improved by 20 dB or 20% SDS. The recovery rates after initial systemic failure are higher than would be expected in this treatment failure group given our control group (9.1%) and literature review. These findings indicate a positive effect from steroid perfusion in this patient population."

• NIDCD-funded Research Explores Use of Laser to Stimulate Auditory Nerve
  from NIDCD.gov
  "The cochlear implant is a great biomedical success story, enabling tens of thousands of people with profound hearing loss to communicate effectively in today’s society. Nevertheless, the ability to decipher speech in more complex environments – such as when there is a lot of background noise – has remained difficult for many users. For this reason, the National Institute on Deafness and Other Communication Disorders (NIDCD), one of the National Institutes of Health (NIH), is seeking ways to improve upon the current technology and provide a more realistic listening experience for people using cochlear implants.
  In one such project, NIDCD-funded researchers from Northwestern University are investigating the development of a cochlear implant that uses light, not electrodes, to stimulate the auditory nerve. Although their work is still being conducted on laboratory animals, the goal is to develop a more precise implant that helps people who have profound hearing loss to distinguish speech in noisy environments."

• Separating Bias and Sensitivity in Judgments of Associative Memory
  from the current issue of the Journal of Experimental Psychology: Learning, Memory, and Cognition
  "Ratings of the degree of association between words are linearly related to normed associative strengths, but the intercept is high, and the slope is shallow (the judgments of associative memory [JAM] function). Two experiments included manipulations intended to decrease the intercept and increase the slope. Discrimination training on many pairs of words and constraining ratings to sum to a constant both reduced the intercept but failed to change the slope. The intercept of the JAM function appears to contain a bias component that can be manipulated independently of the slope, which reflects sensitivity to associative strengths. (PsycINFO Database Record (c) 2007 APA, all rights reserved)"

• Transfer of Noncorresponding Spatial Associations to the Auditory Simon Task
  from the current issue of the Journal of Experimental Psychology: Learning, Memory, and Cognition
  "Four experiments examined transfer of noncorresponding spatial stimulus-response associations to an auditory Simon task for which stimulus location was irrelevant. Experiment 1 established that, for a horizontal auditory Simon task, transfer of spatial associations occurs after 300 trials of practice with an incompatible mapping of auditory stimuli to keypress responses. Experiments 2-4 examined transfer effects within the auditory modality when the stimuli and responses were varied along vertical and horizontal dimensions. Transfer occurred when the stimuli and responses were arrayed along the same dimension in practice and transfer but not when they were arrayed along orthogonal dimensions. These findings indicate that prior task-defined associations have less influence on the auditory Simon effect than on the visual Simon effect, possibly because of the stronger tendency for an auditory stimulus to activate its corresponding response. (PsycINFO Database Record (c) 2007 APA, all rights reserved)"

• Within-Category Discontinuity Interacts With Verbal Rule Complexity in Perceptual Category Learning
  from the current issue of the Journal of Experimental Psychology: Learning, Memory, and Cognition
  "A test of the predicted interaction between within-category discontinuity and verbal rule complexity on information-integration and rule-based category learning was conducted. Within-category discontinuity adversely affected information-integration category learning but not rule-based category learning. Model-based analyses suggested that some information-integration participants improved performance by recruiting more "units" in the discontinuous condition. Verbal rule complexity adversely affected rule-based category learning but not information-integration category learning. Model-based analyses suggested that the rule based effect was on both decision criterion learning and variability in decision criterion placement. These results suggest that within-category discontinuity and decision rule complexity differentially impact information-integration and rule-based category learning and provide information regarding the detailed processing characteristics of these two proposed category learning systems. (PsycINFO Database Record (c) 2007 APA, all rights reserved)"

January 3, 2007

• 7 Things to Know About Preventing, Treating Winter Laryngitis
  from Newswise.com
  "Viral laryngitis is contagious and passes the same way as common colds and flu bugs. To avoid getting laryngitis, a U-M expert suggests seven ways to prevent and treat this inflammation of the voice box, and offers suggestions for caring for your voice even when it’s healthy."

• A 34-year-old man with progressive behavioral and language disturbance
  from the current issue of Neurology
  "A 34-year-old man was referred to the Mayo Clinic for evaluation and treatment of behavioral problems and language disturbance."

• Folic acid supplementation slows hearing loss in older adults
  from the National electronic Library for Medicines (NeLM)
  " A study published in the Annals of Internal Medicine has examined whether folic acid supplementation slows age-related hearing loss. The double-blind, placebo-controlled trial involved 728 older men and women with plasma total homocysteine concentrations 13 micromol/L or greater serum and vitamin B12 concentrations 200 picomol/L or greater at screening, and no middle ear dysfunction, unilateral hearing loss, or pathological ear conditions unrelated to ageing. Patients were randomised to receive either oral folic acid at a dose of 800micrograms once daily or placebo for a period of 3 years. The 3-year change in hearing thresholds was assessed. The following results were reported: • Initial median hearing thresholds were 11.7 dB (interquartile range, 7.5 to 17.5 dB) for low frequencies and 34.2 dB (interquartile range, 22.5 to 50.0 dB) for high frequencies. • After 3 years, thresholds of the low frequencies increased by 1.0 dB (95% CI, 0.6 to 1.4 dB) in the folic acid group and by 1.7 dB (CI, 1.3 to 2.1 dB) in the placebo group (difference, –0.7 dB [CI, –1.2 to –0.1 dB]; P = 0.020). • Folic acid treatment did not affect the decline in hearing the high frequencies. The researchers concluded that folic acid supplementation slowed the decline in hearing of the speech frequencies associated with ageing in a population from a country without folic acid fortification of food (study carried out in The Netherlands). Ref. Ann Intern Med 2007; 146 (1): 1-9."

• High-Normal Uric Acid Linked with Mild Cognitive Impairment in the Elderly
  from Newswise.com
  "Researchers at the Johns Hopkins and Yale university medical schools have found that a simple blood test to measure uric acid, a measure of kidney function, might reveal a risk factor for cognitive problems in old age. Of 96 community-dwelling adults aged 60 to 92 years, those with uric-acid levels at the high end of the normal range had the lowest scores on tests of mental processing speed, verbal memory and working memory."

• Questions regarding environmental mercury release, special education rates, and autism disorder: an ecological study of Texas by Palmer et al.
  from a PubMed abstract of an article in
  "Palmer et al. present an analysis in which they look for an association between Toxic Release Inventory (TRI) reporting data for mercury and rates of autism and special education enrollment in Texas. In their analysis, the link between TRI release data and actual mercury exposure is not clear at all, and thus the conclusions drawn from the analysis are questionable."

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