Frequency Controlled Noise Cancellation for Audio and Hearing Purposes

Methods for hearing aids sought to compensate for loss in hearing by amplifying signals of interest in the audio band. In real-world, audio signals are prone to outdoor noise which can be destructive for hearing aid.  Eliminating interfering noise at high speed and low power consumption became a target for recent researches. Modern hearing compensation technologies use digital signal processing which requires minimum implementation costs to reduce power consumption, as well as avoiding delay in real time processing. In this paper, frequency controlled noise cancellation (FCNC) strategy for hearing aid and audio communication is developed with low complexity and least time delay. The contribution of the current work is made by offering a method that is capable of removing inherent distortion due filter-bank insertion and assigning adaptive filtering to a particular sub-band to remove external noise. The performance of the proposed FCNC was examined under frequency-limited noise, which corrupts particular parts of the audio spectrum. Results showed that the FCNC renders noise-immune audio signals with minimal number of computations and least delay. Mean square error (MSE) plots of the proposed FCNC method reached below -30 dB compared to -25 dB using conventional sub-band method and to -10 dB using standard full-band noise canceller. The proposed FCNC approach gave the lowest number of computations compared to other methods with a total of 346 computations per sample compared to 860 and 512 by conventional sub-band and full-band methods respectively. The time delay using FCNC is the least compared to the other methods

Adaptive cancellation of localised environmental noise

Noise cancellation systems are useful in applications such as speech and speaker recognition systems where the effects of environmental noise have to be taken into considerations. A robust method for the cancellation of localised noise in noisy speech signals using subband decomposition and adaptive filtering is presented and described in this paper. The subband decomposition technique is based on low complexity octave filters that split the noisy speech input into subsidiary bands. A thresholding technique is then applied to the subbands to determine the presence or absence of environmental noise. This is used to control an adaptive filter which only responds to the noisy parts of the speech spectrum hence localising the adaptation process only on these segments. The Normalised Least Mean Squares algorithm (NLMS) is used for the adaptation process. A comparison with a similar system without localising the environmental noise shows the superior performance of the proposed system. It has been shown to perform better in terms of computational costs and convergence rate when compared to a system that does not take advantage of the information regarding the presence or absence of noise in a specific part of the speech spectrum. More than 35 dB of noise has been eliminated in less iterations than in conventional approach which needs longer time to reach steady state

A New Voice Controlled Noise Cancellation Approach

This paper presents a new approach to control the operation of adaptive noise cancellers (ANCs). The technique is based on using the residual output from the noise canceller to control the decision made by a voice activity detector (VAD). Threshold of full band energy feature is adjusted according to the residual output of the noise canceller. In variable background noise environment, the threshold controlled VAD prohibits the reference input from containing some components of actual speech signal during adaptation periods. The convergence behavior of the adaptive filter is greatly improved, since the reference input will be highly correlated with the primary input. In addition, the computation power will be reduced since the output of the adaptive filter will be calculated only during non- speech periods. The threshold controlled noise canceller achieves a cleaner output in about 50% of the time required by a non-controlled noise canceller

Mucocele geante de l’enfant

Les mucocèles sont des formations pseudo kystiques expansives des sinus de la face. Elles sont souvent diagnostiquées tardivement du fait de l’absence de signes spécifiques. Le bilan radiologique basé sur la TDM et ou l’IRM est essentiel pour confirmer le diagnostic et établir le bilan d’extension. Nous rapportons le cas d’un enfant âgé de 4 ans et 6mois traité d’une mucocèle géante éthmoïdo- maxillaire.Mots clés : mucocèle ; enfant ; TDM ; IRM ; chirurgieMucoceles are pseudo-cystic expansive formations of the sinuses. They are often diagnosed lately because of the lack of specific signs. CT and MRI are essential for the diagnosis and to evaluate the extension.We report a case of child with ethmoide-maxillary mucocèle treated in our department.Key words: mucocele; child; CT; MRI; surger

Pyocele du cornet moyen : a propos d’un cas

Introduction : Les mucocèles sont des formations kystiques bénignes mais expansives, tapissées par un épithélium respiratoire, sans connexion avec les cavités sinusiennes ou nasales. Elles se développent le plus souvent dans le complexe ethmoïdofrontal. Le terme pyocèle correspond à une mucocèle dont le contenu est infecté. La localisation turbinale moyenne est exceptionnelle.Observation : Nous rapportons l’observation d’un patient âgé de 75 ans qui se plaignait d’une obstruction nasale chronique gauche. L’examen clinique montrait un cornet moyen élargi obstruant la totalité de la fosse nasale gauche. L’Imagerie (TDM et IRM) a révélée une formation ovalaire d’allure kystique expansive développée aux dépens du cornet moyen, associée à un polype postérieur. Le diagnostic de mucocèle sur concha bullosa a été porté. Le patient a été opéré par voie endonasale avec marsupialisation et polypectomie. Les suites opératoires étaient simples avec amélioration des signes cliniques.Conclusion : Les pyocèles du cornet moyen sont des lésions rares bénignes, toutefois destructrices. Un bilan radiologique est indispensable pour guider le choix du traitement chirurgical. La voie endonasale reste le traitement de référence pour cette pathologie.Mots clés : Concha bullosa, Pyocèle, Obstruction nasaleIntroduction : A mucocele is an epithelium-lined cavity that contains mucus that fills the sinus and is capable of expansion. The majority of mucoceles are situated in the frontal and/or ethmoid sinuses. A pyocele occurs when a mucocele becomes infected. Concha bullosa mucopyocele is a rare entity that presents with persistent nasal symptoms.Case report : This paper presents patient aged 75 who were admitted with persistent nasal complaints. Anterior rhinoscopy showed enlarged middle turbinates obstructing the nasal cavities. MRI and CT Scann revealed expansif cystic lesion in the middle turbinate with a nasal polyp. With the diagnosis of concha bullosa mucocele, lateral part of the affected middle turbinate and the polyp were resected with an endoscopic approach. There were no intraoperative or postoperative complications. Nasal obstruction vanished postoperatively.Conclusion: Mucopyocele of middle turbinate are rare benign lesions. Radiological assessment is essential to guide the choice of surgical treatment. Endonasal approach is the standard treatment for this disease.Key words : Concha bullosa, Pyocele, Nasal obstructio