Speech Privacy In Open-plan Offices Research Articles

Investigation of the Proper Sound Levels of Artificial Masking Sounds for the Speech Privacy in Open-Plan Offices

The present study aims to investigate the optimum level of masking sounds which can satisfy with both the occupants and acoustical privacy. In order to this, prior investigation was accomplished to know real condition of open-plan offices using questionnaire survey to 115 people. Also, acoustic listening experiments were done to 30 people with 5 scale point questionnaire. Recorded voice was played with the output sound level of 57 dB at 1m from the directional speaker. Artificial making sounds were also radiated from the ceiling speakers using pink noise. Making sounds used in the experiments consisted of 5 different sound levels which have SNR of 10, 13, 16, 19 and 22 dB. Using questionnaire, three responses from occupants were received including speech intelligibility, annoyance of masking sounds, and overall unpleasantness. As a result, it was found that SNR 22 is appropriate for the decrease of annoyance of masking sounds and overall unpleasantness while SNR 16 to SNR 19 is considered to be suitable for the reduction of speech intelligibility and the annoyance of masking sounds.

The effect of reverberation time on sound masking method to improve speech privacy in open-plan offices

Lack of speech privacy is a significant problem in open-plan offices. Sound masking, which essentially covers the target speech with the competing speech simultaneously (masker), can increase speech privacy. However, a conversation takes place in a reverberant room at which will reduce speech intelligibility. This study observed the effectiveness of reverberation time on the sound masking to the target. In this early study, three conditions of stimuli were used, namely clean, 0.3 s and 0.6 s reverberation time added to both target and masker, respectively. The STI and subjective measure were used with twenty-five volunteers. As expected, the results suggest that the longer the reverberation time, the lower the effectiveness of the masker strength. The STI agrees with the subjective measure.

Using ODEON acoustical modeling software to predict speech privacy in open-plan offices: Part 2

Speech Privacy Index is one of the commonly used metrics to discuss an occupant’s acoustical comfort in an open-plan office. This paper continues our discussion from the Boston ’17 conference on using the ODEON acoustical modeling software to predict the speech privacy index in open-plan offices. Our original paper examined the effects of using the ODEON provided equation for Articulation Index to calculate Privacy Index, compared these results to “real world” measurements, and attempted to adjust this equation to better fit the Speech Privacy Index (per ASTM 1130-16). In this paper, we will update our analysis to include a larger open-place office floorplate. To continue the discussion, we will also analyze the variation in results, if any, due to changing the scattering coefficients for various materials to determine if this significantly affects the modeled speech privacy results.

Using acoustical modeling software to predict speech privacy in open-plan offices

Speech Privacy Index is one of the commonly used metrics to discuss an occupant’s acoustical comfort in an open-plan office. In existing open-plan offices, the Articulation Index can be measured using a qualified sound source; the Privacy Index can then be calculated from the Articulation Index. However, in the case of future office planning, the Privacy Index must be estimated. Using the ODEON acoustical modeling software, we estimated the Privacy Index in the open-plan section of our office using the existing room dimensions, material finishes, and background noise levels. The ODEON estimates were then compared with “real world” measurements of the same space. This paper summarizes the differences between the estimated and measured speech privacy index levels.

Contributions of various transmission paths to speech privacy of open ceiling meeting rooms in open-plan offices

Installing open ceiling meeting rooms inside a large open-plan office provides a solution to increase speech privacy and to reduce speech disturbance in the office. The open ceiling meeting rooms have advantages of low cost construction and flexibility, but have lower speech privacy than that of enclosed rooms due to the open ceiling. Existing research shows that many factors should be taken into account to achieve good speech privacy in open-plan offices and improving only one of these factors may result in little improvement, so it is important to distinguish contributions of different acoustic transmission paths of open ceiling meeting rooms in open-plan offices. This paper proposes an impulse response separation method to quantify contributions of various acoustic paths of open ceiling rooms on speech privacy in open-plan offices. The method is verified with simulations based on the Odeon software and the experiments carried out in 3 different types of rooms. Finally, the proposed method is applied to the Fabpod, a semi enclosed meeting room located in a large indoor office at the Design Research Institute of the RMIT University, to obtain the contributions of different acoustic transmission paths to its speech privacy. The method proposed in this paper and the knowledge obtained are useful for architects to improve the acoustic performance of the next generation Fabpods which are now under design at RMIT University.

Hybrid actice noise barrier with sound masking in open-plan offices

This paper presents a small-typed active noise barrier (ANB) with sound masking techniques for alleviating the noise problem and protecting the speech privacy in open-plan offices. This soundproof system reduces and masks the undesired sound simultaneously so that lower level of the masker is required to achieve the sound masking effect, comparing with the conventional sound masking systems. First, a real-time experiment to verify the noise attenuation performance of the proposed system for practical application has been conducted in a real office room. In the experiment, the influence of background noise on the system performance has also been investigated. The experiment results show that 3-8 dB active noise attenuation can be achieved behind the ANB in an office room. Moreover, in order to select an appropriate masker for the sound masking part of the system, several maskers have been compared and investigated by listening experiments. The results suggest that the stationary maskers are more suitable for the sound masking in offices by considering the sound masking performance and the annoyance of the maskers comprehensively.

High performance medical clinics: Evaluation of speech privacy in open-plan offices and examination rooms

Speech privacy evaluations of open plan doctors' offices and examination rooms were done at two clinics. One was in Las Vegas and the other in El Dorado Hills. The building were designed to put doctors closer to patients and for a cost savings. ASTM E1130, ASTM E336, and NRC guidelines were used to evaluate these spaces. For E1130, sound is produced at the source location with calibrated speakers, then measurements are made at receiver positions. The speaker faces the receiver. Only open plan furniture separated the source from the receiver. The examination rooms used partial height walls with a single layer of gypsum board on each face. Standard doors without seals were used. CAC 40 rated ceiling tile were installed. The cubicle furniture included sound absorption and was 42 to 60 in. tall. The Privacy Index was quite low, ranging from 30 to 66%. The NIC rating of the walls without doors ranged from 38 to 39, giving PI ratings of 83 to 84%. With a door, the NIC rating was 30 to 31 with PI ratings of 72. These results do not meet the requirements of the Facility Guideline Institute or ANSI 12 Working Group 44.

Multiple maskers for speech masking in open-plan offices

Sound masking is an effective method to reduce speech intelligibility for reaching acceptable speech privacy in open-plan offices. Speech-like masker is considered as a good choice to reduce speech intelligibility. Using one masker in masking system is the common way so far. In this paper, a new method was proposed, using randomly integrated speech frames (SF) of the speaker as masker. Because SF masker was based on speech of the same speaker, it is a good speech-like masker. We further studied the method of using multiple SF maskers. The performance of this new masking method was evaluated by objective measurement (STOI). The speech masked by one SF masker and multiple SF maskers were compared. Results showed that speech with SF masker could reduce speech intelligibility. Speech with multiple SF maskers led to poorer speech intelligibility than speech with only one SF masker. Masking speech by multiple SF maskers is an effective way to reduce speech intelligibility in open-plan offices. (Acknowledgement: This research was supported by the joint training PhD program of Chinese Academy of Sciences-Fraunhofer, and Fraunhofer Institute of Building Physics in Stuttgart, Germany.)

Noise and communication: A three-year update

Noise is omnipresent and impacts us all in many aspects of daily living. Noise can interfere with communication not only in industrial workplaces, but also in other work settings (e.g. open-plan offices, construction, and mining) and within buildings (e.g. residences, arenas, and schools). The interference of noise with communication can have significant social consequences, especially for persons with hearing loss, and may compromise safety (e.g. failure to perceive auditory warning signals), influence worker productivity and learning in children, affect health (e.g. vocal pathology, noise-induced hearing loss), compromise speech privacy, and impact social participation by the elderly. For workers, attempts have been made to: 1) Better define the auditory performance needed to function effectively and to directly measure these abilities when assessing Auditory Fitness for Duty, 2) design hearing protection devices that can improve speech understanding while offering adequate protection against loud noises, and 3) improve speech privacy in open-plan offices. As the elderly are particularly vulnerable to the effects of noise, an understanding of the interplay between auditory, cognitive, and social factors and its effect on speech communication and social participation is also critical. Classroom acoustics and speech intelligibility in children have also gained renewed interest because of the importance of effective speech comprehension in noise on learning. Finally, substantial work has been made in developing models aimed at better predicting speech intelligibility. Despite progress in various fields, the design of alarm signals continues to lag behind advancements in knowledge. This summary of the last three years' research highlights some of the most recent issues for the workplace, for older adults, and for children, as well as the effectiveness of warning sounds and models for predicting speech intelligibility. Suggestions for future work are also discussed.

Prediction of the speech intelligibility index behind a single screen in an open-plan office

Improved acoustical privacy is the principal goal of the acoustical design of open plan offices. As the replacement of the Articulation Index (AI), the Speech Intelligibility Index (SII) can be used as a single-number measure of the speech privacy in open-plan offices. In this paper, a mathematical model of the speech propagation over single screens in a large open-plan office space is presented. The calculated effects of the office parameters, such as the screen height, ceiling and floor absorption, etc. on the SII behind the screen are discussed and are compared with measured results. To facilitate the practical use of the model, an empirical correction is derived from a wide range of ceiling tiles to provide values of the effective sound absorption of typical suspended ceilings in open offices. Compared to measured results, SII can be predicted with an RMS error of 0.03.