Nonlinear Neural System for Active Noise Controller to Reduce Narrowband Noise

Noise in a dynamic system is practically unavoidable. Today, such noise is commonly reduced using an active noise control (ANC) system with the filtered-x least mean square (FXLMS) algorithm. However, the performance of the ANC system with FXLMS algorithm is significantly impaired in nonlinear systems. Therefore, this paper develops an efficient nonlinear adaptive feedback neural controller (NAFNC) to eliminate narrowband noise for both linear and nonlinear ANC systems. The proposed controller is implemented to update its coefficients without prior offline training by neural network. Hence, the proposed method has rapid convergence rate as confirmed by simulation results. The proposed work also analyzes the stability and convergence of the proposed algorithm. Simulation results verify the effectiveness of the proposed method.

Phase-Based Estimation of the Harmonic Signal Frequency

This paper examines estimating the frequency of the information signal based on the analysis of the probability characteristics of the phase fluctuations when a mix of signal and narrowband noise is observed. The new estimation algorithm is described while the shortcomings of the commonly applied methods are specified. The performance of the proposed approach is illustrated by a number of examples. In particular, it is demonstrated that the application of the introduced procedure allows high accuracy measurements of the carrier frequency of the non-modulated, the multilevel phase and quadrature keyed signals.

The Acceptability and Influencing Factors of an Internet-Based Tinnitus Multivariate Integrated Sound Therapy for Patients With Tinnitus

Objective: To explore the acceptability and influencing factors of an Internet-based Tinnitus Multivariate Integrated Sound Therapy (iT-MIST). The individually tailored sound therapy used narrowband noise centered on the patient’s tinnitus frequency in combination with natural sounds and relaxing music. Design: Patients with tinnitus were given a 1-week trial of iT-MIST. Semistructured interviews were then carried out and a thematic analysis used to analyze, identify, organize, and report factors discovered in the data. Study Sample: Semistructured interviews were carried out with 11 participants, 2 women and 9 men, mean age 39.82 years. Results: The first theme identified from patient interview analysis was their motivation to undertake and expectations of iT-MIST. Nearly half of the participants indicated that advice from the physician was considered very important and professional. Benefits acknowledged by most participants from their iT-MIST experience were accessibility, convenience, time- and cost-effectiveness, and emotional benefit. However, a few participants with poor understanding of tinnitus and iT-MIST showed a negative acceptability with doubtful thoughts and complaints about technical issues such as being easily interrupted by messages and phone calls. Conclusion: Patients with tinnitus in this study were not universally accepting of the iT-MIST therapy. Concerns about their tinnitus and ability to comply with doctor’s recommendations were the main influencing factors. Attitude or willingness to explore new therapies facilitated its use. Emotional benefits, for example, relaxation and comfort, were seen to sustain motivation, while doubtful thoughts and technical problems negatively affected acceptability.