Comfort Noise Research Articles

The Working Environment in Primary Healthcare Outpatient Facilities: Assessment of Physical Factors and Health Professionals' Perceptions of Working Environment Conditions.

The objectives of this study were to assess the adequacy of physical parameters/factors (temperature, relative humidity, noise, and illuminance levels) of the work environment in PHC facilities, to evaluate the association between the adequacy of these measured physical parameters and the physical characteristics of the PHC facilities and their surroundings and to assess the association between health professionals' perceptions about exposure to physical risks in the PHC work environment and the adequacy of physical parameters measured in the same facilities. The study monitored 23 PHC facilities in southern Brazil and interviewed 210 health professionals. Data analysis involved Pearson's chi-square, Fisher's exact test, Spearman's correlation, and multivariate linear regression analysis was used to control for confounding factors. The significance level was set at 5% (p ≤ 0.05). The combination of temperature and relative humidity presented thermal comfort levels outside the adopted criteria for adequacy in consultation (outdoor relative humidity, p = 0.013) and procedure rooms (front door open, p = 0.034). Inadequate sound comfort (noise) levels in the morning shift were found in the vaccination (front door open, p = 0.021) and consultation rooms (movement of people, p = 0.016). In PHC facilities where reception rooms had insufficient lighting, internal curtains were opened less frequently (p = 0.047). The analysis of health professionals' perceptions of physical factors demonstrated that physicians more frequently perceive the physical risk of temperature and humidity (p = 0.044). The higher the number of nurses (p = 0.004) and oral health technicians in the PHC facilities (p = 0.031), the greater the general percentage of adequacy of monitored physical parameters. It was also confirmed that the higher the perception of moderate or severe physical risk among health professionals, the lower the general percentage of the adequacy of the physical parameters of the work environment of the PHC facilities evaluated (rs = -0.450, p = 0.031). This study's evidence contributes to a better understanding of physical conditions and future occupational interventions to ensure the comfort, safety, and well-being of PHC workers.

Cozie Apple: An iOS mobile and smartwatch application for environmental quality satisfaction and physiological data collection

Collecting feedback from people in indoor and outdoor environments is traditionally challenging and complex to achieve in a reliable, longitudinal, and non-intrusive way. This paper introduces Cozie Apple, an open-source mobile and smartwatch application for iOS devices. This platform allows people to complete a watch-based micro-survey and provide real-time feedback about environmental conditions via their Apple Watch. It leverages the inbuilt sensors of the smartwatch to collect physiological (e.g., heart rate, activity) and environmental (sound level) data. This paper outlines data collected from 48 research participants who used the platform to report perceptions of urban-scale environmental comfort (noise and thermal) and contextual factors such as who they were with and what activity they were doing. The results of 2,400 micro-surveys across various urban settings are illustrated in this paper, showing the variability of noise-related distractions, thermal comfort, and associated context. The results show that participants experienced at least a little noise distraction 58% of the time, with people talking being the most common reason (46%). This effort is novel due to its focus on spatial and temporal scalability and the collection of noise, distraction, and associated contextual information. These data set the stage for larger deployments, deeper analysis, and more helpful prediction models toward better understanding the occupants’ needs and perceptions. These innovations could result in real-time control signals to building systems or nudges for people to change their behavior.

Micro-characteristics of a naturally ventilated classroom air quality under varying air purifier placements

A naturally-ventilated operational classroom was instrumented at 18 locations to assess spatial variations of classroom air pollution (CRAP), thermal comfort and ventilation indicators under 10 different scenarios (base scenario without air purifier (AP); three single AP scenarios; three scenarios with two APs at same locations; three scenarios with two APs at different locations). Unlike PM2.5, monitored PM10 and CO2 concentrations followed the diurnal occupancy profile. Highest vertical variation (38%) in CO2 was at the classroom entry zone at 40–300 cm height. CO2 increased until 225 cm before stratifying further. PM10 increased to highest levels at children sitting height (100 cm) before decreasing to adult breathing height (150 cm). Highest horizontal variations in CO2 (PM10) were 29% (22%) at 40 cm height between the entry and occupied zones. Teachers' exposure to CO2 (PM10) in breathing zone varied by up to 6% (3%); the corresponding variations across monitored locations were up to 14% (19%). Teachers' exposure to CO2 was up to 13% higher than that of children and 18% lower for PM10. Traffic emissions (PM2.5 and NOx), secondary pollutants (VOCs and O3), thermal comfort parameters and noise level in the classroom varied insignificantly among scenarios. PM10 reduction was not doubled by using two air purifiers, which were most effective when placed within the highest PM concentration zone. Cross-comparisons of scenarios showed: use of AP reduced classroom's spatial average PM10 up to 14%; PM10 was reduced by increasing the AP's filtration capacity; and AP had insignificant impact on spatial average CO2. PM10 showed a maximum reduction of 46% (teacher zone), 62% (occupied zone) and 50% (entry zone) at children's breathing height, depending on usage scenario. This study produced high-resolution data for validating the detailed numerical models for classrooms and informing decision-making on AP's placement to minimise children's exposure to CRAP and re-breathed CO2.

Identification of Dynamic Parameters and Frequency Response Properties of Active Hydraulic Mount with Oscillating Coil Actuator: Theory and Experiment

Active hydraulic mounts (AHMs) provide an effective solution for refining ride comfort noise and vibration in passenger cars. AHMs with inertia tracks, decoupler membranes, and oscillating coil actuators (AHM-IT-DM-OCAs) have been extensively studied owing to their compact structures and strong damping characteristics in the low-frequency band. This study focuses on the full parameter identification based on the distinct features of external dynamics, which can be used to obtain an accurate and reliable estimate of the transfer functions required for active control algorithms. A lumped parameter model was established for the AHM-IT-DM-OCAs, and the analytical frequency bands were defined by the two resonance frequencies of the fluid channel and actuator mover. Methods for nonlinear model simplification were proposed in different bands and verified theoretically. Based on the simplified models, the distinct features of the active and passive dynamics are successively revealed, which include three resonances and seven horizontal segments. Subsequently, a series of experimental studies on the distinct features were carried out, which agreed well with the theoretical results. However, owing to the limitations of the test equipment and fixture modalities, only the distinct features of one fixed point, two resonance peaks, and three horizontal segments can be used for parameter identification. Based on the validated distinct features, a procedure for full parameter identification is proposed, and all six key parameters are identified. The obtained results showed good consistency and rationality, indicating that this approach can be used for the transfer function estimation of the primary and secondary paths of the AHM-IT-DM-OCAs.

Multimode Tree-Coding of Speech with Pre-/Post-Weighting

As speech-coding standards have improved over the years, so complexity has increased, and less emphasis been placed on low encoding/decoding delay. We present a low-complexity, low-delay speech codec based on tree-coding with sample-by-sample adaptive long- and short-code generators that incorporates pre- and post-filtering for perceptual weighting and multimode speech classification with comfort noise generation (CNG). The pre-/post-weighting filters adapt based on the code generator parameters available at both the encoder and decoder rather than the usual method that uses the input speech. The coding of the multiple speech modes and comfort noise generation is accomplished using the code generator adaptation algorithms, again, rather than using the input speech. Codec complexity comparisons are presented and operational rate distortion curves for several standardized speech codecs and the new codec are given. Finally, codec performance is shown in relation to theoretical rate distortion bounds.

Random-Forest Machine Learning Approach for High-Speed Railway Track Slab Deformation Identification Using Track-Side Vibration Monitoring

High-speed railways (HSRs) are established all over the world owing to their advantages of high speed, ride comfort, and low vibration and noise. A ballastless track slab is a crucial part of the HSR, and its working condition directly affects the safe operation of the train. With increasing train operation time, track slabs suffer from various defects such as track slab warping and arching as well as interlayer disengagement defect. These defects will eventually lead to the deformation of track slabs and thus jeopardize safe train operation. Therefore, it is important to monitor the condition of ballastless track slabs and identify their defects. This paper proposes a method for monitoring track slab deformation using fiber optic sensing technology and an intelligent method for identifying track slab deformation using the random-forest model. The results show that track-side monitoring can effectively capture the vibration signals caused by train vibration, track slab deformation, noise, and environmental vibration. The proposed intelligent algorithm can identify track slab deformation effectively, and the recognition rate can reach 96.09%. This paper provides new methods for track slab deformation monitoring and intelligent identification.

Effect of a fragrant tree on the perception of traffic noise

This study investigated the effect of a fragrant tree on the perception of traffic noise, aiming to reveal the interaction between odour and sound in urban environment. Field research investigations including on-site measurement and questionnaire distribution were conducted in two conditions (with and without fragrance) in four streets in Harbin, China, where lilac had been planted. The results showed that fragrance could affect the perception of traffic noise, which was reflected in increased overall comfort of the street, decreased annoyance caused by traffic noise, and improvement in auditory and olfactory satisfaction. The subjective evaluation of a street where double rows of lilac were planted was superior to that of single-row streets, and a decrease in traffic noise annoyance was more evident when the streets had lower traffic noise levels. The study also found that the higher the congruency of the fragrance and the environment, the more comfortable and less annoyed people were. Finally, familiarity, preference, and subjective intensity of fragrance did not correlate with overall comfort or traffic noise annoyance.

Experimental Investigation of Tire Slap Noise

ABSTRACT Tire noise is an important issue both in the vehicle interior and to the vehicle exterior, since it affects passenger comfort and environmental noise levels, respectively. Such noise is increased when a tire encounters discontinuities on the road surface, the discontinuity being either a gap or a bump. The relatively high frequency (e.g., approximately 1 kHz and above) airborne tire noise generated by such discontinuities is defined as tire slap noise in this study. Most previous research on noise generated by surface discontinuities has been focused on lower frequency tire noise, typically below 600 Hz, and, in particular, on structural-borne noise transmitted from the tire into the vehicle associated with the acoustic modes of the tire interior. Here, instead, the focus is on higher frequency airborne transmission. Further, the study here is conducted from the perspective of tire structural vibration, which concerns the vibration of and sound radiation from the tire treadband structure, rather than tire pattern noise, for example. The high frequency tire slap noise was investigated in a laboratory environment. The measurements were conducted by using the Ray W. Herrick Laboratories' Tire Pavement Test Apparatus (TPTA), on which a loaded tire can be run on realistic road surfaces at speeds up to 50 km/h; the resulting tire noise was measured using the On-Board Sound Intensity (OBSI) method. A gap between two different concrete surfaces was chosen as the road discontinuity, and both narrow band and one-third-octave band spectra were recorded over the gap and over the adjacent smooth road surface segments. Several tires were tested on the TPTA, and their slap noise was recorded. Surface noise and slap noise were compared up to 1600 Hz to show the impact of the discontinuity on the tire noise radiation. Generally, slap noise is of a higher level than the surface noise, especially between 800 and 1400 Hz, but some tires showed distinct differences between the noise response on the surface and over the gap, while other tires radiated similar noise on both the surface and over the gap. Moreover, static tire mobility measurements were performed to investigate the wave type responsible for the different responses on the gap and the surface.

High frequency model describing the noise transfer behaviour of automotive hydraulic engine mounts

To further decrease carbon dioxide emissions, efficiency of combustion engines in passenger cars needs to increase. Measures enhancing efficiency in combustion engines significantly increase engine vibrations. In order to provide a high level of comfort and low interior noise levels, isolation properties of engine mount systems have to compensate these increasing excitations. As existing analogous models of hydraulic mounts describe their behaviour only at low frequencies, we elaborate a model describing the isolation properties in a frequency range relevant for dominant engine orders. We deduce this model from parameter variation tests on hydraulic engine mounts using an electrodynamic test bench for characterisation. The parameters in the proposed model represent geometric properties as well as physical properties of springs, masses and dampening effects. Using the elaborated model helps to tune the parameters of engine mounts to the specific demands of different vehicles and to increase isolation properties.

High frequency model describing the noise transfer behaviour of automotive hydraulic engine mounts

To further decrease carbon dioxide emissions, efficiency of combustion engines in passenger cars needs to increase. Measures enhancing efficiency in combustion engines significantly increase engine vibrations. In order to provide a high level of comfort and low interior noise levels, isolation properties of engine mount systems have to compensate these increasing excitations. As existing analogous models of hydraulic mounts describe their behaviour only at low frequencies, we elaborate a model describing the isolation properties in a frequency range relevant for dominant engine orders. We deduce this model from parameter variation tests on hydraulic engine mounts using an electrodynamic test bench for characterisation. The parameters in the proposed model represent geometric properties as well as physical properties of springs, masses and dampening effects. Using the elaborated model helps to tune the parameters of engine mounts to the specific demands of different vehicles and to increase isolation properties.

Modal analysis of different drivetrain configurations in electric vehicles

This paper presents a modal analysis of different drivetrain configurations in electric vehicles; 1) an in – wheel motor, 2) direct drive, and 3) an electric motor with a reduction gear and a differential gear. A specific simulation model was developed to analyze the vibrations while taking into account the traction motor, possible mechanical reduction gears, and the driveshaft, as well as a Rigid Ring Model (RRM) to describe the tire. On the basis of the simulation results, the frequency responses were calculated for each drivetrain configuration and also for a non-drive, free-rolling tire. The analyzed results show interesting differences between the different drivetrain configurations. However, most of the negative aspects can be compensated for if identified in the early design phase. For instance, the frequency response of the in-wheel motor configuration indicated that the vibrations that occur might cause negative effects in terms of driving comfort and wheel speed signal noise. The direct drive configuration has an additional mode at 24 Hz, and the differential configuration at 4 Hz. It is possible that these modes would resonate strongly if some drivetrain design parameters were poorly defined.

Comfort and noise level in infants with helmet interface

Abstract Objectives To evaluate comfort and noise intensity using the COMFORT scale in infants who receive respiratory support with a helmet interface. Patients and methods An observational descriptive study was conducted on all infants (1–12 months of age) admitted to a PICU from November 1st 2013 to March 31th 2014 and who received non-invasive ventilation with a helmet interface. Tolerance to the interface was assessed by use of the COMFORT scale. The intensity of the noise to which the infants were exposed was measured with a TES1350A HIBOK 412 sound-level metre. Three measurements were made every day. Results Twenty-seven patients with bronchiolitis (median age: 54 days; range: 10–256) were included. Median COMFORT score in the first day was 21 points (14–28). An increase in patient comfort was found with a gradual decrease in the scores, with a maximum reduction of 22% from the first hours (score of 22) to the fifth day (score of 18). The minimum sound intensity registered was 42 dB, and the maximum was 78 dB. Background noise intensity was associated with noise intensity in the helmet. No differences were observed in COMFORT score and noise intensity between ventilator devices. Conclusions Helmet interface was well tolerated by infants. COMFORT score results are an indicator that infants were comfortable or very comfortable. The measured noise intensity was in the safe range permitted by World Health Organization.

Contrast‐enhanced spectral mammography (CESM) and contrast enhanced MRI (CEMRI): Patient preferences and tolerance

Contrast-enhanced spectral mammography (CESM) may have similar diagnostic performance to Contrast-enhanced MRI (CEMRI) in the diagnosis and staging of breast cancer. To date, research has focused exclusively on diagnostic performance when comparing these two techniques. Patient experience is also an important factor when comparing and deciding on which of these modalities is preferable. The aim of this study is to compare patient experience of CESM against CEMRI during preoperative breast cancer staging. Forty-nine participants who underwent both CESM and CEMRI, as part of a larger trial, completed a Likert questionnaire about their preference for each modality according to the following criteria: comfort of breast compression, comfort of intravenous (IV) contrast injection, anxiety and overall preference. Participants also reported reasons for preferring one modality to the other. Quantitative data were analysed using a Wilcoxon sign-rank test and chi-squared test. Qualitative data are reported descriptively. A significantly higher overall preference towards CESM was demonstrated (n = 49, P < 0.001), with faster procedure time, greater comfort and lower noise level cited as the commonest reasons. Participants also reported significantly lower rates of anxiety during CESM compared with CEMRI (n = 36, P = 0.009). A significantly higher rate of comfort was reported during CEMRI for measures of breast compression (n = 49, P = 0.001) and the sensation of IV contrast injection (n = 49, P = 0.003). Our data suggest that overall, patients prefer the experience of CESM to CEMRI, adding support for the role of CESM as a possible alternative to CEMRI for breast cancer staging.

Confort y nivel de ruido en ventilación no invasiva con interfase helmet en lactantes

ObjectivesTo evaluate comfort and noise intensity using the COMFORT scale in infants who receive respiratory support with a helmet interface. Patients and methodsAn observational descriptive study was conducted on all infants (1 to 12 months of age) admitted to a PICU from November 1st 2013 to March 31th 2014 and who received non-invasive ventilation with a helmet interface. Tolerance to the interface was assessed by use of the COMFORT scale. The intensity of the noise to which the infants were exposed was measured with a TES1350A HIBOK 412 sound-level meter. Three measurements were made every day. ResultsTwenty seven patients with bronchiolitis (median age: 54 days; range: 10 to 256) were included. Median COMFORT score in the first day was 21 points (14 - 28). An increase in patient comfort was found with a gradual decrease in the scores, with a maximum reduction of 22% from the first hours (score of 22) to the fifth day (score of 18). The minimum sound intensity registered was 42dB, and the maximum was 78dB. Background noise intensity was associated with noise intensity in the helmet. No differences were observed in COMFORT score and noise intensity between ventilator devices. ConclusionsHelmet interface was well tolerated by infants. COMFORT score results are an indicator that infants were comfortable or very comfortable. The measured noise intensity was in the safe range permitted by World Health Organization.

Frequency Band Selection Exited Linear Prediction Wideband Speech/Audio Coding Using SBR

본 논문은 컴포트 노이즈(comfort noise)를 이용하는 주파수 밴드선택 음성/오디오 코덱에서 컴포트 노이즈 대신 SBR(Spectral Band Replication) 기술을 이용하여 여기 신호를 대체 함으로서 밴드 선택 광대역 음성/오디오 부호화기의 성능 향상을 목표로 한다. 비 전송 밴드에 SBR 기술로 합성된 신호를 삽입하기 위하여 부밴드 별로 전송된 신호를 활용하며, 각각의 부밴드 별로 에너지 가중치를 설정한다. 백색잡음 성분의 컴포트 노이즈 대신 전송신호에 의존하는 신호를 합성 함으로서 보다 높은 음질의 밴드 선택 부호화기를 제안하였다. This paper is aimed to improve performance of Band-Selection speech/audio Coder reconstucted band spectrum that is not sent by the comfort noise. To improve the performance, we use the Spectral Band Replication(SBR) technique instead of substitution of Comfort noise. To synthesize SBR signal, the SBR algorithm is referenced in selected signals and the spectrum synthesized by SBR is injected to non-selected band. Each sub-band spectrum has been energy-weighted by real audio signal. We propose the enhanced the Band-Selection Coder that utilizes synthesized SBR signal from selected signal instead of comfort noise.

Effects of the Occupational Physical Environmental Conditions and the Individual Characteristics of the Workers on Occupational Stress and Fatigue

This research was conducted to study the effects of environmental factors i.e. heat stress, thermal comfort, and occupational noise and individual factors of the workers i.e. age, work duration (expressed in months), and nutrition status on occupational fatigue and stress. Occupational fatigue was measured using Reaction Timer L-77 Lakassidaya. Occupational stress was measured using questionnaire adapted from Wambrauw (2010). Heat stress and thermal comfort were measured using Questemp 34 Thermal Environment Meter and Lutron AM-4200 Anemometer. Occupational noise level was measured using Lutron SL-4022 Sound Level Meter. Nutrition status was measured using microtoise and body weight scale. Age and work duration was obtained using a personal profile form filled in by each worker. This research employed Structural Equation Modelling (SEM) consisted of direct and indirect effects of exogenous and endogenous variables on endogenous variables. Data analysis was conducted using AMOS 19 software. Data analysis showed that (1) different level of fatigue was indicated on workers working in different work shifts, (2) there was no direct effects of heat stress and thermal comfort on occupational fatigue, (3) there was a positive direct effect of occupational noise on workers stress but there was no indication that the stress itself has a direct effect on occupational fatigue, thus preventing the indirect effect of occupational noise on occupational fatigue, (4) there was no direct effect of the age of the workers on occupational fatigue, (5) there was a positive direct effect of the workers age on work duration, but the work duration itself did not exhibit any effect on occupational fatigue so therefore no indirect effect of workers age on occupational fatigue was found in this research, (6) and finally, there was a positive direct effect of nutrition status on occupational fatigue. DOI: http://dx.doi.org/10.11591/ijphs.v1i2.1251

분석/합성 구조의 저 전송률 변환여기 광대역 음성/오디오 부호화기 설계

본 논문은 음성과 오디오의 혼합 콘텐츠를 대상으로 하는 9.2 kbps 저 전송률 변환여기 부호화기 설계를 목표로 한다. 저 전송률 환경을 위하여 주파수 영역 신호의 중요도에 따른 Band-Selection 방법과 Gain-Shape 양자화를 이용한 Analysis by Synthesis(AbS) 구조를 이용한다. AbS 구조를 이용하는 과정에서 발생하게 되는 연산량을 감소시키기 위하여 밴드별 IDFT를 취하고 합성하는 방법을 이용한다. 전송 되지 않는 구간에 대하여 Comfort Noise를 삽입함으로써 음질 저하 없이 설계한다. 기존의 TCX모드와 비교하여 저 전송률에서 성능의 저하 없는 부호화기를 제안한다. This paper is aimed to design 9.2 kbps low bits late transform excitation coder that target to voice and audio signal. To set up low bit rate, we used Band-selection in frequency domain and gain-shape quantization and AbS structure. To decrease lots of calculation from ABS structure, we used each band IDFT and synthesis. And we designed non-transfer band for performance by inserting comfort noise. We propose coder that has low bit rate and similar performance comparing with original 10.4 kbps AMR-WB+ TCX mode.

Comparasion of prediction and measurement methods for sound insulation of lightweight partitions

It is important to know the sound insulation of partitions in order to be able to compare different constructions, calculate acoustic comfort in apartments or noise levels from outdoor sources such as road traffic, and find engineer optimum solutions to noise problems. The use of lightweight partitions as party walls between dwellings has become common because sound insulation requirements can be achieved with low overall surface weights. However, they need greater skill to design and construct, because the overall design is much more complex. It is also more difficult to predict and measure of sound transmission loss of lightweight partitions. There are various methods for predicting and measuring sound insulation of partitions and some of them will be described in this paper. Also, this paper presents a comparison of experimental results of the sound insulation of lightweight partitions with results obtained using different theoretical models for single homogenous panels and double panels with and without acoustic absorption in the cavity between the panels.

Noise Generated by Raindrop on Metal Deck Roof Profiles: It's Effect towards People Activities

Noise generated by rain fall on un-insulated metal deck roofs can cause serious acoustic problems in buildings. This paper reports the outcomes of an effect of sound created by rain fall on un-insulated metal deck roofs towards people's activities. The measurement and questionnaire distribution was done at selected UiTM buildings that have been built using un-insulated metal deck roofs. It was found that the occupants facing inconveniences condition that can disturb their activities. The comfort noise level that accepted by the human being is between 55 to 60dB. Therefore, this study substantiates the notion that rain noise can contribute to negative effects in people's lives during rain.

Burst Packet Loss Concealment Using Multiple Codebooks and Comfort Noise for CELP-Type Speech Coders in Wireless Sensor Networks

In this paper, a packet loss concealment (PLC) algorithm for CELP-type speech coders is proposed in order to improve the quality of decoded speech under burst packet loss conditions in a wireless sensor network. Conventional receiver-based PLC algorithms in the G.729 speech codec are usually based on speech correlation to reconstruct the decoded speech of lost frames by using parameter information obtained from the previous correctly received frames. However, this approach has difficulty in reconstructing voice onset signals since the parameters such as pitch, linear predictive coding coefficient, and adaptive/fixed codebooks of the previous frames are mostly related to silence frames. Thus, in order to reconstruct speech signals in the voice onset intervals, we propose a multiple codebook-based approach that includes a traditional adaptive codebook and a new random codebook composed of comfort noise. The proposed PLC algorithm is designed as a PLC algorithm for G.729 and its performance is then compared with that of the PLC algorithm currently employed in G.729 via a perceptual evaluation of speech quality, a waveform comparison, and a preference test under different random and burst packet loss conditions. It is shown from the experiments that the proposed PLC algorithm provides significantly better speech quality than the PLC algorithm employed in G.729 under all the test conditions.