Adaptation by normal listeners to upward spectral shifts of speech: Implications for cochlear implants

Multi-channel cochlear implants typically present spectral information to the wrong ''place'' in the auditory nerve array, because electrodes can only be inserted partway into the cochlea. Although such spectral shifts are known to cause large immediate decrements in performance in simulations, the extent to which listeners can adapt to such shifts has yet to be investigated. Here, the effects of a four-channel implant in normal listeners have been simulated, and performance tested with unshifted spectral information and with the equivalent of a 6.5-mm basalward shift on the basilar membrane (1.3-2.9 octaves, depending on frequency). As expected, the unshifted simulation led to relatively high levels of mean performance (e;g., 64% of words in sentences correctly identified) whereas the shifted simulation led to very poor results (e.g., 1% of words). However, after just nine 20-min sessions of connected discourse tracking with the shifted simulation, performance improved significantly for the identification of intervocalic consonants, medial vowels in monosyllables, and words in sentences (30% of words). Also, listeners were able to track connected discourse of shifted signals without lipreading at rates up to 40 words per minute. Although we do not know if complete adaptation to the shifted signals is possible, it is clear that short-term experiments seriously exaggerate the long-term consequences of such spectral shifts. (C) 1999 Acoustical Society of America. [S0001-4966(99)02012-3]

The role of prostaglandin and antioxidant availability in recovery from forearm ischemia-reperfusion injury in humans

This article is made available through the Brunel Open Access Publishing Fund. It is shared under the Creative Commons License Attribution-Noncommercial No Derivative 3.0 (CCBY NCND). Copyright @ Lippincott Williams & Wilkins.Background: Endothelial dysfunction, manifesting as attenuated flow-mediated dilation (FMD), is clinically important. Antioxidants may prevent this dysfunction; however, the acute effects of oral administration in humans are unknown. Low flow-mediated constriction (L-FMC), a further parameter of endothelial health, is largely unstudied and the mechanisms for this response unclear. Methods: Twelve healthy participants (five women and seven men) completed three test conditions: control; antioxidant cocktail (α-lipoic acid, vitamins C and E); and prostaglandin inhibitor ingestion (ibuprofen). Ultrasound measurements of brachial artery responses were assessed throughout 5 min of forearm ischemia and 3 min after. Subsequently, an ischemia–reperfusion injury was induced by a 20-min upper arm occlusion. Further, vascular function protocols were completed at 15, 30, and 45 min of recovery. Results: Endothelial dysfunction was evident in all conditions. FMD was attenuated at 15 min after ischemia–reperfusion injury (Pre: 6.24 ± 0.58%; Post15: 0.24 ± 0.75%; mean ± SD, P  0.05). The magnitude of L-FMC was augmented at 15 min (Pre: 1.44 ± 0.27%; Post15: 3.75 ± 1.73%; P < 0.05) and recovered by 45 min. Ibuprofen administration produced the largest constrictive response (Pre: −1.13 ± 1.71%; Post15: −5.57 ± 3.82%; time × condition interaction: P < 0.05). Conclusion: Results demonstrate ischemia–reperfusion injury causes endothelial dysfunction and acute oral antioxidant supplementation fails to reduce its magnitude. Our results also suggest that a lack of shear stress during occlusion combined with suppression of prostaglandin synthesis magnifies L-FMC, possibly due to augmented endothelin-1 expression.Society of Biolog

The right information may matter more than frequency-place alignment: Simulations of frequency-aligned and upward shifting cochlear implant processors for a shallow electrode array insertion

Objective: It has been claimed that speech recognition with a cochlear implant is dependent on the correct frequency alignment of analysis bands in the speech processor with characteristic frequencies (CFs) at electrode locations. However, the use of filters aligned in frequency to a relatively basal electrode array position leads to significant loss of lower frequency speech information. This study uses an acoustic simulation to compare two approaches to the matching of speech processor filters to an electrode array having a relatively shallow depth within the typical range, such that the most apical element is at a CF of 1851 Hz. Two noise-excited vocoder speech processors are compared, one with CF-matched filters, and one with filters matched to CFs at basilar membrane locations 6 mm more apical than electrode locations.Design: An extended crossover training design examined pre- and post-training performance in the identification of vowels and words in sentences for both processors. Subjects received about 3 hours of training with each processor in turn.Results: Training improved performance with both processors, but training effects were greater for the shifted processor. For a male talker, the shifted processor led to higher post-training scores than the frequency-aligned processor with both vowels and sentences. For a female talker, post-training vowel scores did not differ significantly between processors, whereas sentence scores were higher with the frequency-aligned processor.Conclusions: Even for a shallow electrode insertion, we conclude that a speech processor should represent information from important frequency regions below 1 kHz and that the possible cost of frequency misalignment can be significantly reduced with listening experience

Radio pulsars around intermediate mass black holes in super stellar clusters

We study accretion in binaries hosting an intermediate mass black hole (IMBH) of 1000 solar masses, and a donor star more massive than 15 solar masses. These systems experience an active X-ray phase characterized by luminosities varying over a wide interval, from <10^36 erg/s up to a few 10^40 erg/s typical of the ultra luminous X-ray sources (ULXs). Roche lobe overflow on the zero-age main sequence and donor masses above 20 solar masses can maintain a long-lived accretion phase at the level required to feed a ULX source. In wide systems, wind transfer rates are magnified by the focusing action of the IMBH yielding wind luminosities around 10^38 erg/s. These high mass-IMBH binaries can be identified as progenitors of IMBH-radio pulsar (PSR) binaries. We find that the formation of an IMBH-PSR binary does not necessarely require the transit through a ULX phase, but that a ULX can highlight a system that will evolve into an IMBH-PSR, if the mass of the donor star is constrained to lie within 15 to 30 solar masses. We show that binary evolution delivers the pre-exploding helium core in an orbit such that after explosion, the neutron star has a very high probability to remain bound to the IMBH, at distances of 1-10 AU. The detection of an IMBH-PSR binary in the Milky Way has suffered, so far, from the same small number of statistics limit affecting the population of ULXs in our Galaxy. Ongoing deeper surveys or next generation radio telescopes like SKA will have an improved chance to unveil such intriguing systems. Timing analysis of a pulsar orbiting around an IMBH would weigh the black hole in the still uncharted interval of mass around 1000 solar massesComment: 10 pages, 8 figures, accepted for publication in MNRAS. Few comments added (minor revision

Contributions of temporal encodings of voicing, voicelessness, fundamental frequency, and amplitude variation to audiovisual and auditory speech perception

Auditory and audio-visual speech perception was investigated using auditory signals of invariant spectral envelope that temporally encoded the presence of voiced and voiceless excitation, variations in amplitude envelope and F-0. In experiment 1, the contribution of the timing of voicing was compared in consonant identification to the additional effects of variations in F-0 and the amplitude of voiced speech. In audio-visual conditions only, amplitude variation slightly increased accuracy globally and for manner features. F-0 variation slightly increased overall accuracy and manner perception in auditory and audio-visual conditions. Experiment 2 examined consonant information derived from the presence and amplitude variation of voiceless speech in addition to that from voicing, F-0, and voiced speech amplitude. Binary indication of voiceless excitation improved accuracy overall and for voicing and manner. The amplitude variation of voiceless speech produced only a small increment in place of articulation scores. A final experiment examined audio-visual sentence perception using encodings of voiceless excitation and amplitude variation added to a signal representing voicing and F-0. There was a contribution of amplitude variation to sentence perception, but not of voiceless excitation. The timing of voiced and voiceless excitation appears to be the major temporal cues to consonant identity. (C) 1999 Acoustical Society of America. [S0001-4966(99)01410-1]

Perceptual adaptation by normally hearing listeners to a simulated "hole" in hearing

Simulations of cochlear implants have demonstrated that the deleterious effects of a frequency misalignment between analysis bands and characteristic frequencies at basally shifted simulated electrode locations are significantly reduced with training. However, a distortion of frequency-to-place mapping may also arise due to a region of dysfunctional neurons that creates a "hole" in the tonotopic representation. This study simulated a 10 mm hole in the mid-frequency region. Noise-band processors were created with six output bands (three apical and three basal to the hole). The spectral information that would have been represented in the hole was either dropped or reassigned to bands on either side. Such reassignment preserves information but warps the place code, which may in itself impair performance. Normally hearing subjects received three hours of training in two reassignment conditions. Speech recognition improved considerably with training. Scores were much lower in a baseline (untrained) condition where information from the hole region was dropped. A second group of subjects trained in this dropped condition did show some improvement; however, scores after training were significantly lower than in the reassignment conditions. These results are consistent with the view that speech processors should present the most informative frequency range irrespective of frequency misalignment. 0 2006 Acoustical Society of America

Discriminating coastal rangeland production and improvements with computer aided techniques

The feasibility and utility of using satellite data and computer-aided remote sensing analysis techniques to conduct range inventories were tested. This pilot study was focused over a 250,000 acre site in Galveston and Brazoria Counties along the Texas Gulf Coast. Rectified enlarged aircraft color infrared photographs of this site were used as the ground truth base. The different land categories were identified, delineated, and measured. Multispectral scanner (MSS) bulk data from LANDSAT-1 was received and analyzed with the Image 100 pattern recognition system. Features of interest were delineated on the image console giving the number of picture elements classified; the picture elements were converted to acreages and the accuracy of the technique was evaluated by comparison with data base results for three test sites. The accuracies for computer aided classification of coastal marshes ranged from 89% to 96%

Teaching in the Middle Grades Today: Examining Teachers’ Beliefs About Middle Grades Teaching

Since the beginning of the middle school movement in the mid-1960s, middle level advocates have called for a school experience for young adolescents grounded in adolescent development that engages students in meaningful learning (Eichhorn, 1966; Alexander & Williams, 1965). The aim of this exploratory multi-case study was to understand middle level teachers’ beliefs about middle level instruction in the current educational environment. To gain this understanding, researchers asked ten current middle grades teachers with varying levels of experience to discuss their beliefs regarding their primary purpose as a middle grades teacher, the current status of middle level teaching, their best and worst instructional lessons, and their perceived barriers to teaching at the middle level. The teachers described the role of teaching in the middle grades as challenging and stressful, but of great importance. In general, they described instruction that included discovery, student engagement, and relevance in an effort to address students’ academic development. There was minimal mention of the non-academic aspects of adolescent development. Finally, teachers viewed curriculum restrictions, students’ attitudes toward learning, difficulty with differentiation, and lack of technology as significant barriers to their success in the classroom

The Status of Middle Schools in the Southeastern United States: Perceptions and Implementation of the Middle School Model

For more than 100 years, education communities have debated how best to educate the young adolescent. Proponents of both the junior high school model and the current middle school model have advocated for a specialized approach to educating adolescents that emphasizes the developmental needs of students. To accomplish this, various organizational structures and instructional approaches are recommended. This survey study examines the perceptions of these middle school practices and the implementation of those practices in middle schools in the Southeastern region of the United States. We note several key trends in our results and highlight key differences in perception of importance and implementation of middle school components and strategies compared to the most recent large scale survey administered by McEwin and Greene (2011)