Application of loudness level to temporally varying sounds
Time: 6:00 am
Author: Sonoko Kuwano
Abstract ID: 1304
Most of the environmental noises are temporally varying and include various frequency components. Various methods for evaluating the environmental noises have been proposed. Among them, the method for calculating loudness level was first standardized in 1975 as ISO 532, including Stevens and Zwickers methods. Unfortunately, these methods can only be applied to steady state sounds. On the other hand, Aeq (Equivalent Continuous A-weight Sound Pressure Level) is standardized for the evaluation of level fluctuating environmental sounds as ISO 1996. In , the energy mean and A-weighting are used for averaging temporal fluctuation and frequency weighting, respectively. The present authors with their colleagues have conducted many psychological experiments using artificial sounds and actual sounds since 1970s and have being introduced that p (Loudness-based Method), which is a combination of ISO 532 for frequency weighting and ISO 1996 for temporal level fluctuation, is a good method for evaluating various kinds of environmental sounds. ISO 532-1 (Zwickers method) has been revised including the temporal fluctuation into consideration in 2017, in which p has been adopted as a note. The merit of p will be introduced in this paper presenting many examples.
Experimental investigation on acoustics and efficiency of rotor configurations for electric aerial vehicles
Time: 8:00 am
Author: Ronja König
Abstract ID: 1435
Aerial vehicles based on distributed electric propulsion systems have gained great interest. Their rotors however create loud and annoying sound, what obstructs market success. Variations in rotor configuration can be observed on emerging concepts, whereby the main varied parameters are blade radius, number of blades and blade distribution. The focus of this paper is to identify how these parameters can be chosen to optimize efficiency and acoustics, including psychoacoustic metrics and sound quality of single rotors while hovering. Results from experimental investigations done in a hover-test-bench are presented. Rectangular, symmetric blades are used. Experiments are done varying blade radius (61mm to 126 mm), number of blades (2 to 8) and blade distribution (equal and unequal angles). Acoustic measurements are analyzed regarding microphone position, sound pressure level, spectral characteristics, psychoacoustic metrics and selected sound quality models. Results show, that variations in blade radius, number of blades and blade distribution can improve efficiency and acoustics. Influence of these parameters on the acoustic signature at constant rotational speed and at constant thrust is discussed. Conclusions for optimized rotor design at aerial vehicles are derived and supplemented by resulting boundary conditions like building space and weight.
Study on psychological evaluation model of a good conversation in knowledge creative activity by multiple people
Time: 6:40 pm
Author: Sohei Tsujimura
Abstract ID: 1478
In recent years, Japanese companies are focusing on enhancing the knowledge creative activities of office workers, and the way of working in the office is shifting from the conventional divisional routine work to collaborative and creative work. On the other hand, office spaces are becoming quiet, and the number of extremely quiet them with noise levels below 40 dB is increasing. Previous studies have reported that a sound environment that is too quiet gives the worker the impression that it is difficult to have a conversation, further accumulation of research results is desired for the construction of a sound environment that enhances knowledge creative activities. Therefore, in this study, focusing on the relationship between sound environment and intellectual productivity, we investigated a sound environment suitable for knowledge creation activities by multiple people. Psychoacoustic experiments were conducted to examine the effects of sound pressure level (signal-to-noise ratio), type of sound and reverberation time of meeting room on the impression of good conversation. Furthermore, using the psychological evaluation data of the experimental participants, the causal model of psychological evaluation of good conversation was examined by multiple regression analysis, and the psychological factors that contribute to the impression of it was clarified.
Time: 12:00 pm
Author: Daniel Carr
Abstract ID: 1484
Automobile manufacturers are trying to improve the interior noise environment in their cars. A more thorough understanding of how people perceive the noise is an important step towards this goal. The focus of the current research is on modeling the acceptability of time-varying wind noises containing gusts. A listening test was designed containing sounds that were simulated on the computer, based on pre-defined airflow profiles. The time-varying noises in the test follow one of two simple gusting scenarios. The primary scenario contained two segments of steady wind flanking a series of consecutive equal-strength gusts. The number, duration, and strength of the gusts were varied between sounds. This was done to examine general trends of acceptability with modulation rate, modulation depth, and duration. The second scenario contained two gusts of equal or unequal strength, occurring either without a break or separated by a time gap. This was done to examine the relationship between peoples reactions to the individual gusts in a pattern and their reactions to the whole pattern. A small number of steady-wind noises were included for reference. Terms in an acceptability model containing a previously proposed gusting metric were estimated. Possible refinements to the metric and model are discussed.
Psycho-acoustic evaluation of the automotive acoustic comfort using vibro-acoustic prediction methods
Time: 12:20 pm
Author: VALENTIN MIQUEAU
Abstract ID: 1630
In the automotive industry, the acoustic comfort is considered as a selling point of utmost importance. To help the OEMs improve the acoustic comfort in cars, as a one-tier supplier of automotive glazing, Saint-Gobain is currently working on the acoustic comfort within the cabin in order to propose the right set of glazing consistent with the OEMs specifications. The characterization of the acoustic comfort mostly relies on physical demonstrators required for carrying out the relevant measurements. It is however not available early in the project phase, delaying the subjective analysis late in the development phase. To have the opportunity to develop effective solutions, the acoustic comfort has to be investigated as early as possible in the design process. Saint-Gobain is thus currently developing relevant acoustic models in order to predict the mid-high frequency airborne interior noise generated by the wind excitations. The subjective acoustic comfort has then to be assessed using the predicted interior sound pressure levels converted into audio soundtracks for the auralization purposes. In this paper, we briefly present the Statistical Energy Analysis model developed by Saint-Gobain. The psychoacoustic methodology deployed to evaluate its reliability for the subjective evaluation of the automotive acoustic comfort is detailed.
Loudspeaker-based sound reproduction for evaluating noise transmission into the car cabin
Time: 11:40 am
Author: Matthieu Kuntz
Abstract ID: 1686
Virtual and laboratory-based design techniques can accelerate the development process over conventional prototype-and-field-test procedures. In car acoustics, the transmission of outside airborne noise into the cabin needs to be understood and managed. Here, we evaluate the accuracy of sound field recording and reproduction techniques for investigating the transmission of airborne noise into the drivers cabin of a car. Reference measurements of a real sound field, generated by a truck with idling engine to create a realistic scenario, were carried out in a semi-anechoic chamber. The reference sound field was recorded inside and around a test car. Additionally, a spatial recording of the reference sound field was carried out and used to reproduce the reference sound field over a loudspeaker array in a different, fully anechoic chamber, where the sound field was again measured inside and around the same test car. A comparison of the measured loudness inside the test car shows that this key parameter for sound quality could be reproduced rather faithfully over a loudspeaker array in a controlled testing facility.
Impact of COVID-19 on the sound environment in a dental office – a case study
Time: 7:00 pm
Author: Tomomi Yamada
Abstract ID: 1900
As of February 2021, COVID-19 has not yet converged globally. Careful countermeasures are required for protecting infection of COVID-19 at dental clinics. Virus particles in saliva are likely to spread outside during dental treatment. Dental staffs must use a variety of personal protective equipment (PPE). In addition, the frequency of using dental aerosol suction devices in the dental office has increased dramatically, and the sound environment in the clinic has changed after taking the measures against COVID-19. In this study, we will report the measurement results of the changes in the sound environment during dental treatment that were perceived by dental healthcare professionals and patients.
An experiment on the feeling of separation when multiple aircraft noises are overlapped
Time: 6:20 pm
Author: Makoto Morinaga
Abstract ID: 2041
In order to calculate the A-weighted single event sound exposure level () of aircraft noise, the following method is described in the manual for aircraft noise measurement in Japan. Firstly a time-section, which is the range between two points where the noise level is 10 dB lower than the maximum noise level (), should be identified, and secondly the energy within the section is integrated. This method can easily be applied to the single event noises. When multiple aircraft noises are overlapped simultaneously, there are cases where cannot be calculated adequately by this method. In such cases, it is required to record the number of aircraft noises in the field measurements. However, even in the case of manned measurement, it is not easy to separate sound sources just by listening to the sound. A pilot study of the psychoacoustic experiment was conducted using the stimuli where multiple aircraft noises were overlapped in order to find what condition is needed so that multiple aircraft noises were separately perceived. It was suggested that a considerable time interval was needed so that people felt the separation between aircraft noises only with auditory information.
Pitch strength and annoyance of acoustic analogs of flutter echo a pilot study
Time: 6:20 am
Author: Anne Balant
Abstract ID: 2062
The impetus for this pilot study was the observation of flutter echoes on the aisle of a church with a barrel-vaulted ceiling. When source and receiver height were comparable, the flutter echoes consisted of a 39-msec repeating pattern of three short pulses that persisted for reverberation times of up to 5 sec. The disruptive quality of these echoes perceptually was striking. It was hypothesized that the perception of a sequence of rapidly alternating periodicity pitches might be the source of this disruptive quality. A pilot study was conducted to assess the perceived pitch, pitch strength, and annoyance of isochronous and anisochronous synthetic pulse trains involving up to three different inter-pulse intervals per pattern. Intervals of the anisochronous pulse trains were controlled to create harmonic and inharmonic relationships among the intervals, which ranged from 5-20 msec. Twelve adult college students participated in the study remotely via videoconferencing due to social distancing requirements. A modified category scaling method was used. Participants positioned a slider on a graphical user interface to reflect their ratings of pitch strength and annoyance and used a slider to adjust the frequency of a reference tone for pitch matching. Results and implications for further research will be presented.
Relationships between prior experience with fan noise and fan noise ratings in laboratory listening tests
Time: 12:40 pm
Author: Stephan Töpken
Abstract ID: 2096
In the assessment of noise annoyance and sound quality, judgments made in the laboratory can be influenced by the prior experience that a participant had with the specific type of sound under test. In field tests for noise annoyance, prior experience and individual noise sensitivity are often part of the data collection but they are not always reported for sound quality evaluations in the laboratory. In this paper, data from listening tests dealing with the perception of fan noise was re-analyzed with respect to the individual prior experience participants had with fan noise in their life. The answers to a short questionnaire showed that the prior experience of the participants with fan sounds was quite different. For the investigated 30 fan sounds, five categories of every-day situations could be identified, in which fan sounds had been most commonly heard by the participants. The frequency how often fan sounds had been heard and the overall annoyance by fan sounds in daily life differed considerably between the participants. However, the exploration of the present data did not reveal a strong link between the individual prior experience and the results of the listening tests when averaged across participants with same ratings.
Loudness- and preference-equivalent levels of fan sounds at different absolute levels
Time: 1:00 pm
Author: Eike Claaßen
Abstract ID: 2100
In daily life, fans are a common and often unwanted noise source. The sound pressure level in dB(A) is often not sufficient to characterize their unpleasantness and level adjustments would be needed to compensate this shortcoming. In this study, listening experiments were conducted to determine loudness- and preference-equivalent levels of 19 different fan noise stimuli. For this purpose, the level of each stimulus was varied with an adaptive procedure until it was equally loud (loudness task), or equally preferred (preference task) as a common reference noise with a fixed level of 75 dB(A). This study repeats an earlier similar study, with a lower reference level of 60 dB(A) and using a larger set of stimuli. The present results are in broad agreement with the results of the prior study, supporting the stability of the matching procedure. Apparently, level adjustments (penalties) derived from such experiments do not change when stimulus levels are increased by 15 dB. Based on the new results, an existing model developed with a 60 dB(A) reference, can be expanded to also predict preferences for sound sources up to 75 dB(A). Further experiments with a reference level of 45 dB(A) will complement the data to lower levels.
Exposure to industrial noise: impacts on cognitive performance
Time: 8:40 am
Author: Björn Knöfel
Abstract ID: 2180
Research on the relation between exposure to noise and cognitive performance inside industrial environments is not as broad as on office environments. For a better understanding of the specific industrial noise problems, participants performed arithmetic tests inside a hemi anechoic room while they were exposed to sounds of five typical industrial noise sources. The subjects also classified how annoying they perceived the noise signals. The effect of noise on the arithmetic tests performance was larger on accuracy than on velocity, which was verified using a Student t-test. Spectral-temporal characteristics especially high frequency content and strong low frequency modulation appear to relate better with lower performance on the test than high sound levels. Subjects that evaluated noise as more annoying performed worse in a final arithmetic test (under silence) after being exposed to the noises, indicating a possible cumulative effect of noise on performance. The findings provide a better insight in the cognitive behavior of people who are exposed to industrial noise. Hence, the study will proceed with the specific noise analysis of single industrial workplaces.
Improvement of sound atmosphere in the compartment of construc-tion machine
Time: 11:00 am
Author: Takeo Hashimoto
Abstract ID: 2487
Noise inside the compartment of construction machine makes the operator feel annoyed and exhausted due to the unwanted component of noise. This paper deals with the treatment of sound inside the compartment of construction machine to make the sound atmosphere desirable for the operator. The main cause of annoyance due to the exposure of noise is the peaky engine order components. This paper provides the method to reduce annoyance for the operator inside by the reduction of peaky components.
Relationship between noise-induced annoyance and age based on data of previous literatures
Time: 8:40 pm
Author: Ke Ni
Abstract ID: 2513
Many studies have investigated subjective responses to noise, but few concerned about the influence of age on the annoyance (discomfort) caused by noise. It is difficult to get a quantitative model featuring the relationship between noise-induced annoyance and age from one or several laboratory studies due to relatively small samples and limited age groups. This paper investigated recent studies (published after the year 2000) on noise-induced annoyance by the literature review method. We classified the studies according to their employed noise types and summarized the quantified subjective values and the ranges of age. The quantitative values of annoyance obtained from variable rating scales were transferred to a uniform scale and normalized. A probability density function then figured out the corresponding annoyance of a certain age under the small sample -distribution assumption. A predicting model of noise-induced annoyance from the age of 755 was proposed, which fitted previous data well.
Subjective hearing sensation of process variations at a milling machine. How reliable will chatter marks be detected?
Time: 8:40 am
Author: Florian Trautmann
Abstract ID: 2599
Intuition enables experienced machine operators to detect production errors and to identify their specific sources. A prominent example in machining are chatter marks caused by machining vibrations. The operators assessment, if the process runs stable or not, is not exclusively based on technical parameters such as rotation frequency, tool diameter, or the number of teeth. Because the human ear is a powerful feature extraction and classification device, this study investigates to what degree the hearing sensation influences the operators decision making. A steel machining process with a design of experiments (DOE)-based variation of process parameters was conducted on a milling machine. Microphone and acceleration sensors recorded machining vibrations and machine operators documented their hearing sensation via survey sheet. In order to obtain the optimal dataset for calculating various psychoacoustic characteristics, a principle component analysis was conducted. The subsequent correlation analysis of all sensor data and the operator information suggest that psychoacoustic characteristics such as tonality and loudness are very good indicators of the process quality perceived by the operator. The results support the application of psychoacoustic technology for machine and process monitoring.
Perceptual Difference on HVAC Sound Quality between Electric and Conventional Vehicles
Time: 6:40 am
Author: Katsuya Yamauchi
Abstract ID: 2629
The heating, ventilation and air-conditioning (HVAC) system is one of the most critical sources in in-vehicle noise environment, especially when cars are moving at low speed or at lower engine rotation. With the transition to electric vehicles (EV) from internal combustion engine vehicles (ICEV), the contribution of powertrain becomes lower on the background noise inside car cabins. The authors have been conducting a collaborative research on HVAC sound quality inside car cabins. In this paper the results of a subjective evaluation of HVAC sound quality were presented, that attempted to compare the perceptual differences among the two groups, i.e. EVs and ICEVs. The result revealed the difference in the noise perception among the two types of vehicles especially softer air flow rate conditions.
Research on the sound quality objective evaluation of a commercial vehicle
Time: 11:20 am
Author: Kun Qian
Abstract ID: 2727
With the increasing demand of users for the acoustical comfort of commercial vehicles, the sound quality has become one of the important indicators of comfort evaluation. The research focuses on the objective evaluation method of the subjective perception of the sound quality in commercial vehicle. The interior noises of commercial vehicle with an inline six diesel engine are measured. The five psychoacoustic parameters (loudness, roughness, sharpness, fluctuation strength, tonality and articulation index) are applied to the evaluation and analysis of the interior noises of the commercial vehicle. Using psychoacoustic parameters to evaluate the noises in commercial vehicle, it is of great significance for the analysis and control of the noises in commercial vehicle. The research results provide a theoretical basis for guiding the sound quality design and development of commercial vehicles.
Equivalent sound level as a predictor for road traffic noise annoyance assessment
Time: 7:40 am
Author: Jan Felcyn
Abstract ID: 2777
Noise annoyance can be rated either in situ or in laboratory conditions. Regarding the , many papers indicate that only 30% of the variance in peoples answers can be explained by sound level values. This value increases when a single type of noise is presented to participants in lab. However, the relationship between time structure of the noise stimulus and annoyance rating is still ambiguous. In this study road traffic noise stimuli with different time structure at three different sound levels were created. Moreover, the psychoacoustical characteristics of them were also computed. The calculated data was compared with results of the listening test in which participants rated each stimulus on the numerical ICBEN scale. Analysis showed that loudness and sound level are the dominant factors, they correlate quite well (~70%) with peoples ratings. However, the different time structure of the road traffic noise at the same sound level did not evoke significantly different noise annoyance ratings. Since there are no standards available for loudness measurement, the sound level for the same type of noise remains the simplest factor to reliably predict its impact on people regarding noise annoyance.
Temporal integration of partial loudness of helicopter-like sounds
Time: 8:20 am
Author: Josef Schlittenlacher
Abstract ID: 2830
When developing new vehicles that are to be operated in existing background noise, such as electric vertical take-off and landing aircraft (eVTOLs) in cities, a sound design goal should be to minimize the loudness in the given background noise. Rotorcraft sounds are characterised by their pulses, and the choice of rotor size and number allows to vary the temporal characteristics. We asked participants to compare the loudness of pulse trains with pulse durations of 1, 2, 5, 10 and 20 ms and a pulse rate of 20 Hz in a two-interval, two-alternatives forced choice task and a 1-up/1-down procedure. Street noise was presented simultaneously with the pulse trains, and had the same root-mean-square (RMS) level as the fixed reference pulse train of about 65 dB SPL. First results indicate that the sounds with a short pulse duration need considerably less RMS level to result in the same loudness as a long pulse duration, i.e. the partial loudness of shorter pulses is higher at the same equivalent sound pressure level.
Effects of speed and road condition on annoyance caused by motorcycle noise emission
Time: 7:00 am
Author: Omid Ghatreh Samani
Abstract ID: 3252
Recently much attention has been drawn to the noise emission of two-wheelers and motorcycles. Considering the high levels of noise pollution and annoyance caused by motorcycles, it is necessary to evaluate the contribution of their noise emission to the overall traffic noise. Furthermore, this emission must be included in traffic noise studies and noise maps. In order to have a clear understanding of the noise characteristics of this vehicle category, extensive studies are required. This paper aims to investigate the effects of speed and road condition on annoyance caused by motorcycle noise emission. For this purpose, noise measurements are carried out for various engine speeds, and road conditions. These stimuli are used later in a perceptual experiment to realize the effect of each parameter on the caused annoyance. Stimuli are reproduced in the laboratory where participants can determine their annoyance toward each stimulus. Finally, based on the outcome of the perceptual experiment and analysis of psychoacoustic parameters, a conclusion is drawn to clarify how annoyance and noise emission alter in response to the changes in speed and road condition.