STI direct test method based on wavelet transform to extract envelope

Speech transmission index (STI for short) is an important index to evaluate the quality of speech transmission of the room, it can better reflect the degree of voice signal affected by room reverberation and noise in the transmission process.This paper presents an algorithm for directly measuring STI index, white noise is filtered by Paul Kellet filter to generate pink noise, the signal envelope is extracted by wavelet transform, which improves the extraction accuracy of signal envelope and makes the measurement of STI index more accurate.

Object Localization and Tracking System Using Multiple Ultrasonic Sensors with Newton–Raphson Optimization and Kalman Filtering Techniques

In this paper, an object localization and tracking system is implemented with an ultrasonic sensing technique and improved algorithms. The system is composed of one ultrasonic transmitter and five receivers, which uses the principle of ultrasonic ranging measurement to locate the target object. This system has several stages of locating and tracking the target object. First, a simple voice activity detection (VAD) algorithm is used to detect the ultrasonic echo signal of each receiving channel, and then a demodulation method with a low-pass filter is used to extract the signal envelope. The time-of-flight (TOF) estimation algorithm is then applied to the signal envelope for range measurement. Due to the variations of position, direction, material, size, and other factors of the detected object and the signal attenuation during the ultrasonic propagation process, the shape of the echo waveform is easily distorted, and TOF estimation is often inaccurate and unstable. In order to improve the accuracy and stability of TOF estimation, a new method of TOF estimation by fitting the general (GN) model and the double exponential (DE) model on the suitable envelope region using Newton–Raphson (NR) optimization with Levenberg–Marquardt (LM) modification (NRLM) is proposed. The final stage is the object localization and tracking. An extended Kalman filter (EKF) is designed, which inherently considers the interference and outlier problems of range measurement, and effectively reduces the interference to target localization under critical measurement conditions. The performance of the proposed system is evaluated by the experimental evaluation of conditions, such as stationary pen localization, stationary finger localization, and moving finger tracking. The experimental results verify the performance of the system and show that the system has a considerable degree of accuracy and stability for object localization and tracking.

Signal envelope and speech intelligibility differentially impact auditory motion perception

Our acoustic environment contains a plethora of complex sounds that are often in motion. To gauge approaching danger and communicate effectively, listeners need to localize and identify sounds, which includes determining sound motion. This study addresses which acoustic cues impact listeners’ ability to determine sound motion. Signal envelope (ENV) cues are implicated in both sound motion tracking and stimulus intelligibility, suggesting that these processes could be competing for sound processing resources. We created auditory chimaera from speech and noise stimuli and varied the number of frequency bands, effectively manipulating speech intelligibility. Normal-hearing adults were presented with stationary or moving chimaeras and reported perceived sound motion and content. Results show that sensitivity to sound motion is not affected by speech intelligibility, but shows a clear difference for original noise and speech stimuli. Further, acoustic chimaera with speech-like ENVs which had intelligible content induced a strong bias in listeners to report sounds as stationary. Increasing stimulus intelligibility systematically increased that bias and removing intelligible content reduced it, suggesting that sound content may be prioritized over sound motion. These findings suggest that sound motion processing in the auditory system can be biased by acoustic parameters related to speech intelligibility.

New Results and Applications about the Level Crossing Rate of SC Receiver output Signal in the Presence of Gamma Shadowing and k-μ or Rician Multipath Fading

In this paper,the wireless communication system with dual SC receiver operating over shadowed multipath fading channel is considered. The multipath fadingis k-μor Rician.The received signal experiences the short term fading which is resulting in SC receiver envelope variation and Gamma long term fading resulting in SC receiver envelope power variation. The closed form expressions for joint probability density functions of SC receiver output signal envelope and their first derivative of SC receiver output signal envelope are calculated for both, k-μand Rician fading. These expressions are used for evaluation of average level crossing rate of SC receiver output signal envelopes. The numerical expressions are plotted to show the effect of Rician fading severity parameter and Gamma shadowing severity parameter on the average level crossing rate of SC receiver output signal envelope.

Method of demodulation of radio pulses, based on the application the principle of coherent samples

The paper proposes a radio pulse demodulation method which allows to extract the signal envelope by taking coherent samples with a frequency not exceeding the carri-er frequency of the received signal. The paper demonstrates the possibility of creation of inertia-free demodulators based on the proposed method, whose principle of op-eration is reduced to performing basic operations in the time domain and forming samples, whose position corresponds to the expected amplitude values of the carrier oscillation and depends on its frequency. Calculations of the errors in determining the amplitude of demodulated signal, the factors affecting the errors, and ways to reduce them are shown. The specific results of studies of the capabilities of the proposed method obtained on the model of a base-based digital demodulator are presented.