Effect of the Target and Conflicting Frequency and Time Ranges on Consonant Enhancement in Normal-Hearing Listeners

In this paper, the effects of intensifying useful frequency and time regions (target frequency and time ranges) and the removal of detrimental frequency and time regions (conflicting frequency and time ranges) for consonant enhancement were determined. Thirteen normal-hearing (NH) listeners participated in two experiments. In the first experiment, the target and conflicting frequency and time ranges for each consonant were identified under a quiet, dichotic listening condition by analyzing consonant confusion matrices. The target frequency range was defined as the frequency range that provided the highest performance and was decreased 40% from the peak performance from both high-pass filtering (HPF) and low-pass filtering (LPF) schemes. The conflicting frequency range was defined as the frequency range that yielded the peak errors of the most confused consonants and was 20% less than the peak error from both filtering schemes. The target time range was defined as a consonant segment that provided the highest performance and was decreased 40% from that peak performance when the duration of the consonant was systematically truncated from the onset. The conflicting time ranges were defined on the coincided target time range because, if they temporarily coincide, the conflicting frequency ranges would be the most detrimental factor affecting the target frequency ranges. In the second experiment, consonant recognition was binaurally measured in noise under three signal processing conditions: unprocessed, intensified target ranges by a 6-dB gain (target), and combined intensified target and removed conflicting ranges (target-conflicting). The results showed that consonant recognition improved significantly with the target condition but greatly deteriorated with a target-conflicting condition. The target condition helped transmit voicing and manner cues while the target-conflicting condition limited the transmission of these cues. Confusion analyses showed that the effect of the signal processing on consonant improvement was consonant-specific: the unprocessed condition was the best for /da, pa, ma, sa/; the target condition was the best for /ga, fa, va, za, ʒa/; and the target-conflicting condition was the best for /na, ʃa/. Perception of /ba, ta, ka/ was independent of the signal processing. The results suggest that enhancing the target ranges is an efficient way to improve consonant recognition while the removal of conflicting ranges negatively impacts consonant recognition.

Follow-up care delivery in community-based hypertension and type 2 diabetes management: a multi-centre, survey study among rural primary care physicians in China

Background Follow-up care is crucial but challenging for disease management particularly in rural areas with limited healthcare resources and clinical capacity, yet few studies have been conducted from the perspective of rural primary care physicians (PCPs). We assessed the frequency of follow-up care delivered by rural PCPs for hypertension and type 2 diabetes – the two most common long-term conditions. Methods We conducted a multi-centre, self-administered survey study built upon existing general practice course programmes for rural PCPs in four provinces. Information on follow-up care delivery were collected from rural PCPs attending centralised in-class teaching sessions using a set of close-ended, multiple choice questions. Binary logistic regression analysis was performed to examine physician-level factors associated with non-attainment of the target frequency of follow-up care for hypertension and type 2 diabetes, respectively. The final sample consisted of rural PCPs from 52 township-level regions. The Complex Samples module was used in the statistical analysis to account for the multistage sample design. Results The overall response rate was 91.4%. Around one fifth of PCPs in rural practices did not achieve the target frequency of follow-up care delivery (18.7% for hypertension; 21.6% for type 2 diabetes). Higher education level of physicians, increased volume of daily patients seen, and no provision of home visits were risk factors for non-attainment of the target frequency of follow-up care for both conditions. Moreover, village physicians with less working experiences tended to have less frequent follow-up care delivery in type 2 diabetes management. Conclusions Efforts that are solely devoted to enhancing rural physicians’ education may not directly translate into strong motivation and active commitment to service provision given the possible existence of clinical inertia and workload-related factors. Risk factors identified for target non-attainment in the follow-up care delivery may provide areas for capacity building programmes in rural primary care practice.

Acoustic notch filtering earmuff utilizing Helmholtz resonator arrays

In recent years, noisy bustling environments have created situations in which earmuffs must soundproof only specific noise while transmitting significant sounds, such as voices, for work safety and efficiency. Two sound insulation technologies have been utilized: passive noise control (PNC) and active noise control (ANC). However, PNC is incapable of insulating selective frequencies of noise, and ANC is limited to low-frequency sounds. Thus, it has been difficult for traditional earmuffs to cancel out only high-frequency noise that people feel uncomfortable hearing. Here, we propose an acoustic notch filtering earmuff utilizing Helmholtz resonator (HR) arrays that provides a sound attenuation effect around the tuneable resonant frequency. A sheet-like sound insulating plate comprising HR arrays is realized in a honeycomb structure. Since the resonant frequency is determined by the geometry of the HR arrays, a highly audible sound region can be designed as the target frequency. In this research, the acoustic notch filtering performance of the proposed HR array plate is investigated in both simulations and experiments. Furthermore, the fabricated earmuffs using the novel HR array plates achieve a sound insulation performance exceeding 40 dB at the target frequency, which is sufficiently high compared to that of conventional earmuffs. The experimental results confirm that the proposed device is a useful approach for insulating frequency-selective sound.

Radio Station Background Noise Detection Based on Time-Frequency Domain Electromagnetic Spectrum

The electromagnetic spectrum resource is one of the important national resources. It is a physical channel for wireless communication between ships and between ships and radio stations. Good communication quality must be guaranteed, so it is urgent to monitor and analyze the environmental background noise of the electromagnetic spectrum. The estimation of the radio frequency signal coverage in the target area during the monitoring process is of great significance to the study of electromagnetic spectrum resource management and control. This paper estimates the upper envelope and lower envelope of the background noise of the target frequency band based on the electromagnetic spectrum data in the time-frequency domain and combines the forward difference algorithm to estimate the background noise envelope curve. We set up fixed detection nodes and mobile detection nodes for specific construction areas and collect time-frequency spectrum data of electromagnetic spectrum in multiple locations. The instantaneous frequency spectrum and the collected data of a specific frequency point are compared, and it is difficult to judge whether there is a valid signal. This paper is based on the time-frequency domain electromagnetic spectrum data in the construction area of the project and estimates the background noise of the coast station frequency band in the current environment. It is based on the energy gradient estimation of the time-frequency domain spectrum, and the effective signal of the target frequency band is obtained and combines the noise envelope and the effective signal location to improve the estimation result of the background noise envelope. The experimental results show that the background noise estimation algorithm can reflect the changes in the noise floor of different target frequency bands.

LHCP four patches stack triangular truncated antenna using corporate feed microstrip-line for CP-SAR sensor

<span>In this paper, we acquire the configuration of the left-hand circular polarization (LHCP) array four patches stack triangular truncated microstrip antenna. This construction use the basic corporate feed microstrip-line with modified lossless T-junction power divider on radiating patch for circularly polarized-synthetic aperture radar (CP-SAR) sensor embedded on unmanned aerial vehicle (UAV) with compact, small, and simple configuration. The design of circular polarization (CP) is realized by truncating the whole three tips and adjusting the parameters of antenna at the target frequency, <em>f </em>= 5.2 GHz. The results of characteristic performance and <em>S</em>-parameter for the LHCP array four patches stack antenna at the target frequency show successively about 9.74 dBic of gain, 2.89 dB of axial ratio (<em>Ar</em>), and </span><span>-</span><span>10.91 dB of S-parameter. Moreover, the impedance bandwidth and the 3 dB-<em>Ar</em> bandwidth of this antenna are around 410 MHz (7.89%) and 100 MHz (1.92%), respectively.</span>

Design of a metamaterial-based muffler for a target frequency range

This work proposes an acoustic metamaterial-based muffler that effectively blocks a transmission noise for a target frequency range. Since the acoustic metamaterial-based muffler consists of arrayed unit cells, its noise attenuation performance is strongly affected by the internal layout of the unit cell. The wave transmission characteristics of an acoustic metamaterial is explained by the effective bulk modulus and dispersion curve of an unit cell. Therefore, the internal layout of the unit cell should be optimally designed so that its band gap should include the target frequency range of a muffler. To the end, an acoustical size optimization problem is formulated to design a unit cell of the muffler and is solved for a given design requirement. The noise blocking frequency range of the unit cell is characterized by the bandgap in its dispersion curve during the optimization process. The wave transmission characteristics of the metamaterial muffler is validated experimentally.