Comparing Binaural Pre-processing Strategies I: Instrumental Evaluation.

In a collaborative research project, several monaural and binaural noise reduction algorithms have been comprehensively evaluated. In this article, eight selected noise reduction algorithms were assessed using instrumental measures, with a focus on the instrumental evaluation of speech intelligibility. Four distinct, reverberant scenarios were created to reflect everyday listening situations: a stationary speech-shaped noise, a multitalker babble noise, a single interfering talker, and a realistic cafeteria noise. Three instrumental measures were employed to assess predicted speech intelligibility and predicted sound quality: the intelligibility-weighted signal-to-noise ratio, the short-time objective intelligibility measure, and the perceptual evaluation of speech quality. The results show substantial improvements in predicted speech intelligibility as well as sound quality for the proposed algorithms. The evaluated coherence-based noise reduction algorithm was able to provide improvements in predicted audio signal quality. For the tested single-channel noise reduction algorithm, improvements in intelligibility-weighted signal-to-noise ratio were observed in all but the nonstationary cafeteria ambient noise scenario. Binaural minimum variance distortionless response beamforming algorithms performed particularly well in all noise scenarios.

Comparing Binaural Pre-processing Strategies II: Speech Intelligibility of Bilateral Cochlear Implant Users.

Several binaural audio signal enhancement algorithms were evaluated with respect to their potential to improve speech intelligibility in noise for users of bilateral cochlear implants (CIs). 50% speech reception thresholds (SRT50) were assessed using an adaptive procedure in three distinct, realistic noise scenarios. All scenarios were highly nonstationary, complex, and included a significant amount of reverberation. Other aspects, such as the perfectly frontal target position, were idealized laboratory settings, allowing the algorithms to perform better than in corresponding real-world conditions. Eight bilaterally implanted CI users, wearing devices from three manufacturers, participated in the study. In all noise conditions, a substantial improvement in SRT50 compared to the unprocessed signal was observed for most of the algorithms tested, with the largest improvements generally provided by binaural minimum variance distortionless response (MVDR) beamforming algorithms. The largest overall improvement in speech intelligibility was achieved by an adaptive binaural MVDR in a spatially separated, single competing talker noise scenario. A no-pre-processing condition and adaptive differential microphones without a binaural link served as the two baseline conditions. SRT50 improvements provided by the binaural MVDR beamformers surpassed the performance of the adaptive differential microphones in most cases. Speech intelligibility improvements predicted by instrumental measures were shown to account for some but not all aspects of the perceptually obtained SRT50 improvements measured in bilaterally implanted CI users.

Retinal vasculitis in Susac syndrome: case report.

A 29 year old male was admitted at the emergency room suffering from gradually worsening headache followed by nausea. In the hospital patient presented with lethargy, reduction of consciousness level and bilateral hypoacusis. Ophthalmic examination and fluorescein angiography showed retinal vasculitis. This finding was crucial to the diagnosis of Susac syndrome, a rare disease characterized by vasculopathy of retina, encephalic tissues and cochlea. Patient was treated with immunosuppressors to prevent him from developing severe sequelae of this disease.

Retinal vasculitis in Susac syndrome: case report / Vasculite retiniana na síndrome de Susac: relato de caso

A 29 year old male was admitted at the emergency room suffering from gradually worsening headache followed by nausea. In the hospital patient presented with lethargy, reduction of consciousness level and bilateral hypoacusis. Ophthalmic examination and fluorescein angiography showed retinal vasculitis. This finding was crucial to the diagnosis of Susac syndrome, a rare disease characterized by vasculopathy of retina, encephalic tissues and cochlea. Patient was treated with immunosuppressors to prevent him from developing severe sequelae of this disease.

Paciente masculino de 29 anos foi admitido em pronto-socorro com quadro de cefaléia progressiva há 10 dias seguida de náuseas. Durante internação evoluiu com letargia, redução do nível de consciência e hipoacusia bilateral. Exame oftalmológico e angiofluoresceinografia evidenciaram vasculite retiniana. Este achado foi essencial para o diagnóstico de síndrome de Susac, uma patologia rara caracterizada por vasculopatia de retina, encéfalo e cóclea. Tratamento imunossupressor foi instituído, prevenindo sequelas graves da doença.

Expression of the ggpPS gene for glucosylglycerol biosynthesis from Azotobacter vinelandii improves the salt tolerance of Arabidopsis thaliana.

Many organisms accumulate compatible solutes in response to salt or desiccation stress. Moderate halotolerant cyanobacteria and some heterotrophic bacteria synthesize the compatible solute glucosylglycerol (GG) as their main protective compound. In order to analyse the potential of GG to improve salt tolerance of higher plants, the model plant Arabidopsis thaliana was transformed with the ggpPS gene from the gamma-proteobacterium Azotobacter vinelandii coding for a combined GG-phosphate synthase/phosphatase. The heterologous expression of the ggpPS gene led to the accumulation of high amounts of GG. Three independent Arabidopsis lines showing different GG contents were characterized in growth experiments. Plants containing a low (1-2 micromol g(-1) FM) GG content in leaves showed no altered growth performance under control conditions but an increased salt tolerance, whereas plants accumulating a moderate (2-8 micromol g(-1) FM) or a high GG content (around 17 micromol g(-1) FM) showed growth retardation and no improvement of salt resistance. These results indicate that the synthesis of the compatible solute GG has a beneficial effect on plant stress tolerance as long as it is accumulated to an extent that does not negatively interfere with plant metabolism.