Long-Term Average Speech Spectra and Dynamic Ranges of 17 Indian Languages.

PURPOSE: In this work, we have determined the long-term average speech spectra (LTASS) and dynamic ranges (DR) of 17 Indian languages. This work is important because LTASS and DR are language-dependent functions used to fit hearing aids, calculate the Speech Intelligibility Index, and recognize speech automatically. Currently, LTASS and DR functions for English are used to fit hearing aids in India. Our work may help improve the performance of hearing aids in the Indian context. METHOD: Speech samples from native talkers were used as stimuli in this study. Each speech sample was initially cleaned for extraneous sounds and excessively long pauses. Next, LTASS and DR functions for each language were calculated for different frequency bands. Similar analysis was also performed for English for reference purposes. Two-way analysis of variance was also conducted to understand the effects of important parameters on LTASS and DR. Finally, a one-sample t test was conducted to assess the significance of important statistical attributes of our data. RESULTS: We showed that LTASS and DR for Indian languages are 5-10 dB and 11 dB less than those for English. These differences may be due to lesser use rate of high-frequency dominant phonemes and preponderance of vowel-ending words in Indian languages. We also showed that LTASS and DR do not differ significantly across Indian languages. Hence, we propose a common LTASS and DR for Indian languages. CONCLUSIONS: We showed that differences in LTASS and DR for Indian languages vis-à-vis English are large and significant. Such differences may be attributed to phonetic and linguistic characteristics of Indian languages.

Modelling of a hydroacoustic projector to produce low frequency sound.

Low frequency sound is useful in several underwater applications, including sonar, underwater communication, detection of mines, sonobuoys, detection of oil or gas deposits, etc. Hydroacoustic projectors help in generating such low frequency acoustic waves far more effectively than other devices. Even though there is sufficient information available on modelling of various components used in complex hydraulic devices, there is a significant dearth of literature pertaining to mathematical modelling of hydroacoustic projectors and relevant experimental data. The present work fills this gap firmly. To this end, an integrated electrical analogy-based model to simulate the behavior of a hydroacoustic projector has been developed. The model includes sub-models for a hydraulic pump, hydraulic pipelines, hydraulic cylinders, a directional control valve, an accumulator, a reservoir, mechanical mass, spring, friction, radiation impedance, and coupling elements. The model also incorporates the effects of compliance in pipelines and presence of air in the working fluid. Further, a prototype of the projector has been designed and fabricated. Predictions from simulations have been compared with experimental results from tests conducted in air up to 10 Hz frequency. These results demonstrate the reliability of the simulation model and establish its efficiency in terms of predicting the projector's performance with reasonable accuracy.

A device for three-dimensional quantitative assessment and alignment of C1-2 vertebrae during posterior distraction and fusion technique for atlantoaxial dislocation and/or basilar invagination.

The most common type of congenital C1-2 dislocation is a combined type in which atlanto-axial dislocation (AAD) and basilar invagination (BI) are often associated with a rotational dislocation and coronal tilt. An optimal surgical treatment involves reduction of AAD and BI with simultaneous correction of the rotation and coronal tilt to achieve an optimal cervical canal decompression, sagittal and coronal realignment and bony fusion. The most acceptable technique to facilitate this correction is the C1-C2 distraction technique, which is accomplished by the manual joint manipulation. In this study, the authors describe an instrument that accomplishes distraction of the C12 joint space along with its quantitative assessment, permits the easy installation of a joint spacer without damage to the articular surfaces, brings about reduction of AAD and BI, while simultaneously also helping in the correction of the coexisting coronal tilt and rotational dislocation. This distractor not only achieves a multi-planar three-dimensional correction of the displacements at the C1-2 vertebral level, but may be used for the quantitative assessment of the correction and is compatible with the related surgical instruments of all standard companies utilized in this operative procedure.

The structure of Hindi stop consonants.

The pronunciation of stop consonants varies markedly with age, gender, accent, etc. Yet by extracting appropriate cues common to these varying pronunciations, it is possible to correctly identify the spoken consonant. In this paper, the structure underlying Hindi stop consonants is presented. This understanding may potentially be used as a "recipe" for their artificial synthesis. Hindi alphabet stops were analyzed for this purpose. This alphabet has an organized and comprehensive inventory of stop consonants, and its consonants invariably terminate with the neutral vowel schwa. While the former consideration makes the findings potentially applicable to many languages including English, the latter rationale helped reduce the endeavor's analytical complexity. The alphabet has velar, palatal, retroflex, dental and bilabial stops in voiceless-unaspirated, voiceless-aspirated, voiced-unaspirated, voiced-aspirated, and nasal flavors. It is shown that additive combinations of relatively simple acoustic functions can be used to generate most of the 20 non-nasal stops. This work will potentially help speech therapists improve diagnosis and rectification of speech and hearing disabilities, speed up electronic communication of audio data, and improve voice recognition.