Loudness Of Noise Research Articles

Enhancing autumn greenway walking experience: Exploring the combined effects of noise and thermal environment.

The evaluation of outdoor green spaces is influenced by diverse sensory perceptions. Traffic noise and thermal conditions significantly impact greenway-walking satisfaction; their optimization is vital for improving user experience and encouraging outdoor engagement. The study examines a typical Beijing greenway during autumn, focusing on strategies to enhance the walking experience under the combined effects of noise and thermal environments through mobile measurements and surveys. The results show that: 1) The interplay between noise and thermal factors varies depending on the walking state. Upon arrival, an increase in noise significantly worsens thermal comfort; higher sound levels intensify warm thermal sensations, though this effect is not consciously perceived. Upon departure, the effect of noise on thermal perception is not obvious. In both walking states, thermal sensation significantly affects subjective noise perception, yet the trends of influence differ. Subjective noise loudness increases as thermal comfort worsens, showing significant correlation only upon departure. 2) During autumn greenway walks, acoustic factors exert a greater impact on Overall Environmental Satisfaction (OES), with subjective noise loudness being more influential than noise level, followed by air temperature (Ta). Greater noise decreases OES, while OES increases initially with Ta and then decreases. The integrated effects of noise-thermal factors on OES show significant changes. 3) To enhance the autumn greenway-walking experience, the advised parameters are A-weighted Sound Level (ASL) ≤ 59.12 dBA and 15.17°C ≤ Ta ≤ 18.75°C. Finally, three design strategies are proposed: reducing subjective noise loudness, differentiating design based on walking status and balancing acoustic-thermal perceptual preferences.

Validation of auralized impulse responses considering masking, loudness and background noise

The use of outdoor virtual scenarios promises to have a lot of potential to facilitate reproducible sensory evaluation experiments in laboratory. Auralizations allow for the integration of simulated or measured sound sources and transfer paths between the sources and receivers. Nonetheless, pure simulations can lack perfect plausibility. This contribution investigates the augmentation of auralized outdoor scenes based on simulated impulse responses (IRs) by ambient or background sounds. For this purpose, foreground events such as car pass-bys are created by simplified simulation of impulse responses. Due to their large number of events, however, ambient sounds are typically not simulated. Instead, spherical microphone array recordings can be used to capture the background sound. Using synthesized car sounds, we examine how much the augmentation by background sound improves the auditory plausibility of simulated impulse responses in comparison with the equivalent measured ones.

Pilot study on evaluation indices for aircraft noise considering sound quality

In Japan, Lden is currently used as an evaluation index for aircraft noise. It is based on the A-weighted sound pressure. It evaluates differences in noise loudness, but it does not necessarily take into account differences due to changes in sound quality. Over the past several decades, single event of aircraft noise has been significantly reduced. As a result, we have experienced a change from the "noisy" sound quality of the old generation jets to the "soft" sound quality of the recent aircrafts. Has the sound quality really improved, and has its improvement been evaluated? On the other hand, since the 2000's, we have sometimes experienced hearing the extraordinary tonal sounds from landing aircraft. It has the characteristics of pure tonal tone with 250-500 Hz and has a short duration and a prominent level fluctuation. Doessuch a sudden tonality change, which is also negatively perceived, not affect the evaluation? This paper describes the results of trial calculation in order to examine the possibility of evaluating aircraft noise considering its sound quality, based on several indices such as EPNL, loudness, sharpness, and Tonal Audibility (TA), in addition to the A-weighted noise (LAmax, LEA), and its comparative verification including differences in aircraft generations.

Dynamic EEG changes during exposure to noise at different levels of loudness and sharpness

From a psychological standpoint, noise can disturb human mental performance in the workplace. While loudness and sharpness of noise are usable factors for evaluating the subjective effects of noise exposure, there has been comparatively less focus on their influence on human reaction time and the dynamic changes in brain waves. Therefore, this study aimed to investigate the temporal changes in the theta beta ratio (TBR) and reaction time (RT) before and during exposure to different noise loudness and sharpness levels. Eight different loudness and sharpness levels of noise were generated and broadcast. Sixty-four men performed the Integrated Visual and Auditory (IVA) test both before and during exposure to the generated noise, and their brain waves were recorded simultaneously. The main step of the IVA test lasted approximately 12 min and consisted of 250 visual and 250 auditory stimuli presented randomly. The highest difference in TBR before and during exposure to various loudness levels was associated with 65 phon at 250 Hz and 75 phon at 4000 Hz, with values of 0.86 and 0.75, respectively. This difference equaled 0.69 for the 1.23 acum sharpness level at a frequency of 4000 Hz. In addition, the sharpness of 3.29 acum at a frequency of 8000 Hz led to the highest difference equaling 0.71 in TBR between before and during exposure to various sharpness levels. The most significant difference in RT was observed before and during exposure to lower loudness levels (65 and 75 phon), resulting in 405.75 and 347.5 ms, respectively. This highest difference was also observed for sharpness levels of 1.23 (391.4 ms) and 3.29 acum (427.4 ms) compared to other sharpness levels. Furthermore, attention deficit increased with longer exposure times to all noise levels. The results showed a statistically significant correlation between TBR and RT during exposure to all noises. Specifically, lower loudness at frequencies of 250 and 4000 Hz and higher sharpness at frequencies of 4000 and 8000 Hz had the most significant impact on the attention parameter. In psychoacoustics studies, it is important to consider both the frequency and duration of exposure in addition to assessing the loudness and sharpness level of noise.

The Influence of Noise Exposure at Different Loudness Levels on EEG Index and Types of Attention.

Noise is one of the most important harmful factors in the environment. There are limited studies on the effect of noise loudness on brain signals and attention. The main objective of this study was to investigate the relationship between exposure to different loudness levels with brain index, types of attention, and subjective evaluation. Four noises with different loudness levels were generated. Sixty-four male students participated in this study. Each subject performed the integrated visual and auditory continuous performance test (IVA-2) test before and during exposure to noise loudness signals while their electroencephalography was recorded. Finally, the alpha-to-gamma ratio (AGR), five types of attention, and the subjective evaluation results were examined. During exposure to loudness levels, the AGR and types of attention decreased while the NASA-Tax Load Index (NASA-TLX) scores increased. The noise exposure at lower loudness levels (65 and 75 phon) leads to greater attention dysfunction than at higher loudness. The AGR was significantly changed during exposure to 65 and 75 phon and audio stimuli. This significant change was observed in exposure at all loudness levels except 85 phon and visual stimuli. The divided and sustained attention changed significantly during exposure to all loudness levels and visual stimuli. The AGR had a significant inverse correlation with the total score of NASA-TLX during noise exposure. These results can lead to the design of methods to control the psychological effects of noise at specific frequencies (250 and 4000 Hz) and can prevent non-auditory damage to human cognitive performance in industrial and urban environments.

Enhancing understanding of real-world listening experiences: Insights from ecological momentary assessments with assistive listening technologies

Comprehending the daily listening experiences of people who use assistive listening technologies is difficult due to individual differences and the variety of listening environments they encounter. Consequently, a lack of comprehensive insight into real-world experiences often leads to misconstrued interpretations of research outcomes and future technological directions. Addressing this issue, the National Acoustic Laboratories (NAL) in Sydney, Australia, has been actively investigating the applications of ecological momentary assessments (EMA) since 2010. By employing EMA, NAL aims to comprehend the impact of assistive listening technologies in real-world conditions. To achieve this, we invested data from four distinct studies, encompassing more than 3000 survey entries. Utilizing an EMA app specifically developed by NAL, participants reported various challenges they faced in their listening experiences. These challenges include difficulties in understanding conversation when listening to a single speaker or in multitasking scenarios, as well as frustration with the loudness and annoyance of background noise. The analysis of this extensive dataset involved a combination of conventional statistical methods and advanced machine learning models. By employing these techniques, key insights were extracted from the data, offering valuable guidance for the design of future research conducted in real-world settings.

Sequence optimization for MRI acoustic noise reduction

The large acoustic noise of 80-110 dB during magnetic resonance imaging (MRI) scanning harms patients’ comfort and health. The noise can be reduced by hardware modification or active noise control, but these methods are expensive, difficult, or not very effective. In this study, a sequence optimization method is used to mitigate the acoustic noise problem while maintaining image quality. The 4th order polynomial function is applied to design the new quiet pulse sequences, decreasing the gradient slew rate and higher time derivatives of the original trapezoidal lobes. A sound pressure level (SPL) estimation method is proposed to predict the acoustic noise loudness from the gradient and is used for genetic algorithm sequence optimization. The original and quiet gradient recalled echo (GRE) sequences are applied on a 1.5 T MRI scanner. The average SPL is reduced by 18.6 dBA, and the images show small differences and have similar SNR values. This method is also applied for the scouting and shimming GRE sequences in common clinical applications with significant noise reduction.

Effect of roadside trees on pedestrians' psychological evaluation of traffic noise.

This study aims to investigate the interplay between roadside trees and pedestrians' assessment of traffic noise and comfort. The study examines the potential effects of visual and design elements of roadside trees on the overall soundscape comfort. The study design involves a systematic exploration of different conditions, encompassing traffic volume, distance from sound source, and tree density. For each combination, two experimental scenarios are created: (1) participants experience a binaural sound recording exclusively, and (2) participants experience the same binaural recording while concurrently immersed in a virtual reality (VR) video. Analysis of participants' noise perception, measured using a quiet-noisy scale, reveals no significant disparity between conditions. This suggests that the mere presence of roadside trees does not necessarily lead to a perceived reduction in noise loudness. However, evaluation of sound intensity exposes a notable discrepancy between low and medium tree density levels. Furthermore, the study confirms the impact of roadside tree visibility, with scenes containing trees yielding more positive evaluations compared to sound-only scenarios. Remarkably, the absence of trees in the roadside scene garners consistent evaluations across both experimental conditions. Significantly, higher roadside tree density in conjunction with the combined sound and VR video condition prompts a more favorable assessment than the sound-only scenario. While the study indicates that roadside trees might not substantially mitigate perceived physical noise levels, their influence on the psychological well-being of urban inhabitants is considerable. The findings highlight that even though these trees may not overtly diminish noise, they hold substantial potential to enhance the overall comfort and well-being of city residents. This underscores the multifaceted benefits of integrating green spaces into urban design for improving the quality of urban soundscapes and residents' experiences.

An objective and subjective study on global active control of engine noise in a car

The work tests and analyzes the engine noise distribution in a car with and without active control, where the car’s built-in loudspeakers are used as secondary sources to attenuate the engine noise inside the whole cabin. To analyze the sound field in detail, the noise level at 52 microphones on the passenger ears’ plane is measured and presented. The distributions of the primary overall noise, first four order noise of the engine, and the sound field generated by the subwoofer at engine orders’ frequencies are reported, and the noise reductions corresponding to overall engine noise and each order’s noise are analyzed. Besides, jury test is presented and compared with the calculated loudness of residual noise to evaluate the acoustic comfort improvement of the system. The experiment results show that the overall noise reduction is achieved inside the whole cabin by controlling the first four orders’ engine noise. The average noise reduction of the measurement area inside the cabin is 6.2 dB and 2.9 dBA. Besides, 93% of the participants feel the acoustic comfort is improved with the active noise control system on.

Speech Signal Processing of Industrial Speech Recognition

The noise in the industrial production environment is more complex than the application scenario in the home or office environment, and the most of the noise loudness is much larger. Automatic speech recognition(ASR) system will fail when the front-end speech signal processing SNR is too poor. At this time the front-end speech signal processing ability is particularly important. The product solution mentioned in this article involves multiple point. It includes omnidirectional Microphones Array scheme selection, selection of Mic monomer, sampling, digitization, noise reduction and echo processing, so as to improve the overall SNR and improve the speech recognition rate under noise,therefore, it has become an AR head-mounted computer for industrial intelligent speech recognition accepted by many business worldwide.

Active sound quality control of vehicle interior noise using a dual sampling-rate active noise equalization algorithm

In-vehicle active sound quality control (ASQC) system is an advanced application of active noise control (ANC) technology, which always suppresses the interior sound pressure or improves the psychoacoustic features. However, the connection between the sound quality control state and the vehicle's working state is normally ignored, and the passenger's sound perception typically expects a linear relationship between the vehicle speed and sound loudness. This paper presents a dual sampling-rate active noise equalization algorithm. The low sampling-rate signal is used to improve system computing efficiency, the high sampling-rate signal is used to improve the ASQC effect, and their conversion communication uses a hold (low to high) and a sampler (high to low). The data relating to the ASQC system was collected, and some sound quality evaluations were conducted for determining two appropriate sampling-rate values. Combining a genetic algorithm and the corresponding ASQC simulation system, the algorithmic optimal convergence coefficients and gain coefficients were further determined at different engine speeds. The verification results of ASQC using this proposed algorithm show that the loudness of interior noise is effectively suppressed; the nonlinear index is reduced to 1.37, improving by 37% relative to the original noise and by 20% compared to the ANC system.

Evaluations of the Annoyance Effects of Noise

Noise is defined as audible sound that disrupts silence and causes annoyance. Such annoyance is traditionally assessed by the A-weighted sound pressure level of noise, roughly corresponding to the level of perceived loudness. However, the A-weighted scale is inapplicable for analyzing tonal, pulsed, and predominantly low-frequency noise; therefore, methods have been developed for calculating noise loudness in linear units, sones, which take into account not only auditory sensitivity, but also masking properties and auditory temporal effects. The existence of noise reduction limits and their informational significance have led to other methods for assessing noise annoyance. Annoyance, in addition to loudness, is caused by such subjective noise qualities as sharpness, roughness, fluctuation strength, tonality, etc. Units of measurements have been defined for these and calculation methods developed. Taking such qualities into account, a metric of short-term psychoacoustic annoyance (PAA) has been proposed, which is valid for many types of noise. Another method for evaluating PAA includes conducting an auditory examination and constructing a mathematical model that relates the rank of auditory annoyance to the measured subjective qualities of the noise. The resulting model helps to identify the causes of annoyance (subjective annoying qualities); develop work plans aimed at noise suppression, the formation of pleasant noise by machines and mechanisms; and control changes in the rank of annoyance in the implementation of such plans. This paper compares different methods for assessing the annoyance caused by noise recorded in Moscow subway cars.

Spectral and binaural loudness summation of equally loud narrowband signals in single-sided-deafness and bilateral cochlear implant users.

Recent studies on loudness perception of binaural broadband signals in hearing impaired listeners found large individual differences, suggesting the use of such signals in hearing aid fitting. Likewise, clinical cochlear implant (CI) fitting with narrowband/single-electrode signals might cause suboptimal loudness perception in bilateral and bimodal CI listeners. Here spectral and binaural loudness summation in normal hearing (NH) listeners, bilateral CI (biCI) users, and unilateral CI (uCI) users with normal hearing in the unaided ear was investigated to assess the relevance of binaural/bilateral fitting in CI users. To compare the three groups, categorical loudness scaling was performed for an equal categorical loudness noise (ECLN) consisting of the sum of six spectrally separated third-octave noises at equal loudness. The acoustical ECLN procedure was adapted to an equivalent procedure in the electrical domain using direct stimulation. To ensure the same broadband loudness in binaural measurements with simultaneous electrical and acoustical stimulation, a modified binaural ECLN was introduced and cross validated with self-adjusted loudness in a loudness balancing experiment. Results showed a higher (spectral) loudness summation of the six equally loud narrowband signals in the ECLN in CI compared to NH. Binaural loudness summation was found for all three listener groups (NH, uCI, and biCI). No increased binaural loudness summation could be found for the current uCI and biCI listeners compared to the NH group. In uCI loudness balancing between narrowband signals and single electrodes did not automatically result in a balanced loudness perception across ears, emphasizing the importance of binaural/bilateral fitting.

Change in Preferred Gain, Word Recognition Scores, and Sound Qualities as Hearing Aid Wearing Period

Purpose: The purpose of this study was to assess the changes in gain, aided threshold, word recognition in noise, and sound quality of hearing aids according to the first wearing period of sensorineural hearing loss (SNHL) to determine the rehabilitation goal and effective adjustments of the electroacoustic parameters. Methods: The subjects of this study were 17 SNHL (26 ears) who had no experience in wearing hearing aids, with an average age of 67.5 years, an average pure-tone average of 50.5 dB HL, an average WRS of 68.9%, and a K-IOI-HA (Korean version of International Outcome Inventory for Hearing Aids) score of 25 or higher. The procedure for gain adjustment of the hearing aid was through NAL-NL2 (National Acoustic Laboratories, non-linear version 2) at first adjustment and subjective responses of the subject afterwards. Real-ear insertion gain, aided threshold, WRS in noise, and sound quality evaluation were conducted at week 0 (initial fit), week 2, and week 6 (or final visit). Results: The study showed a higher gain in 55 dB sound pressure level at most frequencies and improved aided thresholds at 1,000 Hz and 2,000 Hz as the wearing period increased. WRS also increased in 10 dB and 5 dB signal-to-noise ratios, and the sharpness, occlusion, and loudness of noise were shown to improve despite the increased gain. Conclusion: Despite the limitation of gain change with the wearing period, the results of this study expect to aid in setting rehabilitation goals according to the wearing period and adjusting electroacoustic parameters.

Changes in Speech Recognition Scores and Sound Quality According to Gain Adjustment in High Frequency Bands

Purpose: In this study, changes before and after adjustment in high frequency bands were assessed for aided threshold, psychoacoustic evaluation, word recognition scores (WRSs) in noise and sound quality to aid in electroacoustic adjustment, and to improve the satisfaction of hearing aids.Methods: The subjects were 16 sensorineural hearing impaired (25 ears) with 63.4 years old of mean age, 60.8% WRS and 46.6 months of aided experience. For the experiment, hearing aid gain of high-frequency bands adjusted to preferred gain was increased to a higher level. Aided threshold, Korean version of international outcome inventory for hearing aids (K-IOI-HA), Korean version of profile of hearing aid benefit-quick version (K-PHAB-Q), WRSs in noise for 10 dB and 5 dB signal-to-noise ratio (SNR) and sound quality were subsequently evaluated after two weeks and the results were quantitatively compared before and after gain adjustment in high-frequency bands.Results: This study results in as follows; first, improvement in aided threshold for frequencies above 2.0 kHz was shown. Second, K-IOI-HA and K-PHAB-Q in easy communication and localization categories resulted in significant enhancements. Third, WRS in 5 dB and 10 dB SNR was improved. Fourth, improvements were shown for occlusion and clarity of the sentence in the evaluation of sound quality, but significant results were not shown for sharpness and loudness of noise conditions.Conclusion: With sensorineural hearing loss, a sufficient gain in high frequency bands provides improved satisfaction to hearing aids and enhanced word recognition ability in various listening environments.

Investigation of Metrics for Assessing Human Response to Drone Noise.

Novel electric air transportation is emerging as an industry that could help to improve the lives of people living in both metropolitan and rural areas through integration into infrastructure and services. However, as this new resource of accessibility increases in momentum, the need to investigate any potential adverse health impacts on the public becomes paramount. This paper details research investigating the effectiveness of available noise metrics and sound quality metrics (SQMs) for assessing perception of drone noise. A subjective experiment was undertaken to gather data on human response to a comprehensive set of drone sounds and to investigate the relationship between perceived annoyance, perceived loudness and perceived pitch and key psychoacoustic factors. Based on statistical analyses, subjective models were obtained for perceived annoyance, loudness and pitch of drone noise. These models provide understanding on key psychoacoustic features to consider in decision making in order to mitigate the impact of drone noise. For the drone sounds tested in this paper, the main contributors to perceived annoyance are perceived noise level (PNL) and sharpness; for perceived loudness are PNL and fluctuation strength; and for perceived pitch are sharpness, roughness and Aures tonality. Responses for the drone sounds tested were found to be highly sensitive to the distance between drone and receiver, measured in terms of height above ground level (HAGL). All these findings could inform the optimisation of drone operating conditions in order to mitigate community noise.

Hybrid vibro-acoustic active control method for vehicle interior sound quality under high-speed

For the problem of active noise control (ANC) and active vibration control (AVC) methods, only noise and vibration can be controlled separately. Active sound quality control (ASQC) method and AVC method are combined to carry out an in-depth study on the active control method of vehicle interior sound quality, using the vibration-sound transfer function and considering the requirements of sound quality. Combined with the adaptive noise equalizer (ANE) algorithm, a sound retention factor was introduced on the basis of the hybrid vibro-acoustic filter-u and filter-x least mean square (HVA-FUXLMS) algorithm, a hybrid vibro-acoustic adaptive noise equalizer (HVA-ANE) algorithm was proposed to control the sound quality. Based on the filter-error least mean square algorithm (FELMS) algorithm, a hybrid vibro-acoustic empirical-mode-decomposition frequency-domain block filter-error least mean square (HVA-EMDFELMS) algorithm for vehicle interior sound quality was proposed. Vibration and noise at high speeds are collected and analyzed for sound quality levels. This article used HVA-ANE and HVA-EMDFELMS algorithms to perform ASQC simulation experiments. The results showed that the noise loudness was greatly reduced while the noise and vibration control was taken into account by the HVA-ANE algorithm and HVA-EMDFELMS algorithm. Hybrid vibro-acoustic active control method for vehicle interior sound quality can effectively improve the sound quality of vehicle and can be applied to the active control of vehicle noise and related engineering noise.

A Method for Quantifying Automobile Brake Creep Groan Intensity Based on Friction-Induced Vibration and Noise

To quantify the intensity of automobile brake creep groan, both experimental and analytical studies are innovatively conducted on the friction-induced vibration and noise of the disc brake in this paper. Experimentally, three factors, brake disc initial temperature, terrain, and gear position, are comprehensively contemplated to design six different test conditions, based on which a creep groan vehicle road test is conducted. Depending on the subjective evaluation and statistical analysis of the annoyance degree caused by vibration and noise in the starting and braking process under different test conditions, the influence of each factor on creep groan intensity is obtained. By processing the brake caliper and lower suspension arm acceleration and the interior sound pressure signals acquired in the test, the occurrence conditions and transient dynamic characteristics of creep groan are explored. One of the creep groan vibration modes is triggered by the rapid removal of the force exerted on the brake pedal when the vehicle starts at an extremely low speed, which presents intermittent impact and chaotic characteristics. The other vibration mode shows periodic harmonic characteristics, whose energy is concentrated on specific frequencies in the form of frequency doubling. This vibration mode occurs when continuously maintaining a low brake oil pressure or slowly releasing the force exerted on the brake pedal during the vehicle low-speed starting process, the velocity-displacement phase-plane portrait of which shows a stable limit cycle of stick-slip motion. Analytically, four vibration indexes and four noise indexes are established to evaluate the intensity of creep groan, the validity of which is verified by linear regression analysis. Finally, by combining all effective indexes, multiple linear regression analysis is performed, based on which the mapping relationship between the subjective evaluation of creep groan and effective indexes is obtained. The results demonstrate that the combination of the logarithmic vibration dose value of maximum brake caliper acceleration pulse and the loudness of interior noise can accurately describe the annoying degree caused by creep groan. The regression model can quantify and predict creep groan intensity of the test vehicle under different test conditions, which has guiding significance for engineering applications.

PSX-A-9 Late-Breaking: Effects of farm noise on ileum intestinal barrier function of pullets

Abstract Noise is a potential but not negligible environmental factor in animal husbandry. To investigate the effects of farm noise on intestinal barrier function of pullets, 336 Hailanhe pullets aged 1 day were randomly divided into 3 groups: control group (CON), low noise group (LN), high noise group (HN). LN group and HN group were exposed to noise respectively at 65–75 dB and 85–95 dB, the average and the range of the highest loudness of noise in laying hens’ farms for 6h every day (7:00-19:00, hourly intervals for one hour) and lasted 4 weeks. Non additional noise addition in CON group, noise loudness of which was less than 40dB. 6 birds were randomly chosen form each group after every week of noise stimulation for ileum tissue samples. Hematoxylin-eosin stain (HE stain), immunofluorescence, and real-time quantitative PCR (qRT-PCR) were used to determine changes in ileum structure, expression of intestinal barrier related proteins and mRNAs and HSPs. Results shown that 1 week and 2 weeks after noise exposed inflammatory cell infiltration reduced, the expression of intestinal barrier related proteins (Occludin, Mucin2 and ZO-1) and mRNAs (Claudin-1, Claudin-4, E-cadherin, Occludin, Mucin2, ZO-1 and ZO-2) were significantly increased (P < 0.05), the mRNA expression of HSPs decreased (P < 0.05) or have no significate changes (P > 0.05). After 4 weeks of noise treatment, the expression of mRNAs of intestinal tight junction protein and mucin, HSPs were significantly decreased (P < 0.05). There was no difference between the LN and HN groups on those indicators (P > 0.05). The study indicates that noise at 65-75dB and 85-95dB does not cause stress to ileum of pullets while promote the development of intestinal barrier of chicks within 2 weeks maybe by mild stimulation and birds restored to balance due to habitualization after 4 weeks of noise treatment.

Environmental factors related to sleep latency among inpatients in rehabilitation wards according to functional independence measure cognitive scores.

No study has investigated sleep-related environmental factors in patients according to their functional independence measure (FIM) cognitive scores. The aim of this study is to examine the associations between environmental factors such as noise and sleep latency according to the FIM cognitive scores among inpatients in rehabilitation wards. This is a prospective longitudinal study. This study measured the sleep state using a bed-based actigraphy, environmental data from Environmental Sensor®, and medical record information of 33 inpatients in the rehabilitation wards during 2018. A linear mixed-effect model was used to analyse the associations between sleep latency and environmental factors. Participants were grouped according to high or low FIM cognitive scores. The average patient age was 77.2 ± 10.9 years, and 48.5% were male. In the high FIM cognitive score group, the loudness and frequency of noise exceeding 40 dB during sleep latency were significantly associated with sleep latency. In the low FIM cognitive score group, only the noise frequency was associated with sleep latency, and intra-individual variance was larger than that of the high group. These findings suggest that providing night care with attention to subdued noise is important, particularly for patients with low cognitive functional independence levels measured by the FIM cognitive score.