•In situ assessment of effects of office noise on cognitive performance and annoyance.•Use of sound level measurements to assess impact of background speech on workers.•Percentile level differences ...of sound conditions correlate with effects on workers.•No clear relationships of energy-equivalent sound levels with performance and annoyance.•Level statistics consider effects on performance and perception in occupied offices.
Acoustical privacy is one of the most crucial, yet least satisfying aspects in open-plan offices. Irrelevant background speech impairs acoustic satisfaction and cognitive performance. Assessing acoustical conditions in occupied offices is challenging, and thus room acoustic parameters are commonly determined in unoccupied offices. In German speaking countries the rating level of noise is an important parameter occupational safety and health practitioners in the field often use to assess the acoustical conditions in occupied offices. The rating level denotes the energy-equivalent sound pressure level during a measurement period in an occupied office with speech sounds and takes penalties for tonal, informational and impulsive constituents into account. There is little evidence that the rating level correlates with the well-being, performance or health of office workers. As part of this study 89 different sound conditions under which subjects have to complete a number recall task and a questionnaire in laboratory conditions are evaluated with respect to their relationships with the rating level. In addition, these results are compared to percentile level statistics suggested as an alternative approach to assess the acoustical quality of office workplaces. Higher differences between the 10th and 90th percentile levels measured with fast time weighting lead to lower number recall performances and higher annoyance ratings whilst the rating level does not show any clear relationships.
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•Sound masking reduces distraction due to speech at −6 dB speech-to-noise ratio.•Babble masking sound improves cognitive performance similarly to broadband noise.•Babble sounds may ...not recover working memory performance to baseline condition.•Sound masking with babble is perceived as more annoying than with broadband noise.
Background speech has a detrimental impact on employees’ privacy perception and cognitive performance in open-plan offices. Sound masking that covers speech sounds can help to improve the speech privacy and the ability to work undisturbed in open office environments. Recently, non-artificial sounds such as babble or water sounds have been suggested as masking sounds because they may be perceived as more natural and subsequently less annoying. This paper compares the working memory performance and annoyance perception during background speech that was masked by different babble sounds and a waterfall sound to speech that was masked by stationary noise with the frequency spectrum of the distracting background speech signal (target speech). In a first laboratory experiment the effects of different babble sounds were compared with the noise sound at a speech-to-noise ratio of −3 dB. All subjects had to complete a serial short-term memory task and a questionnaire that covered subjective ratings. All sound conditions with masked target speech produced similar error rates and annoyance ratings as unmasked target speech. In a second laboratory experiment, the speech-to-noise ratio of target speech that was masked by babble consisting of 48 target speech signals was varied between −6 and −12 dB in steps of 3 dB. Target based babble resulted in similar error rates as stationary noise at −6 dB speech-to-noise ratio but the findings suggest that target speech that is masked by babble might even be perceived as more annoying than speech that is masked by stationary target spectrum based noise.
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•Sound masking reduces cognitive performance impairment due to distracting speech.•Local sound masking improves performance similarly as conventional sound masking.•Presenting masking ...and speech sound from similar location increases the performance.•Spatial separation of sounds affects cognitive performance more than annoyance.•125 Hz octave band constituents in masking sound improve the cognitive performance.
Sound masking is a well-known measure to reduce the detrimental impact of irrelevant background speech in open-plan offices. However, the impact of the location of sound masking loudspeakers on the efficiency of masking systems with regard to cognitive performance has not yet been evaluated. This aspect is particularly important in decentralised sound masking architectures that enable individualised solutions but may depend highly on spatial release from masking. This paper reports on a study in an open-plan office with laboratory-like conditions. The subjects performed a serial recall task and completed a questionnaire during twelve different sound conditions with five different loudspeaker sets. With regard to serial recall performance, a disadvantage was observed when the speech and masker signals were presented from different horizontal directions of 90° as opposed to the same direction. Moreover, a similar disadvantage occurred when the masking sound was presented over six conventional sound masking loudspeakers that were mounted in the ceiling and positioned in a grid spacing of 2.4 m. However, when the cutoff frequency of the high-pass filter that was applied to the masker signal was lowered from 200 to 100 Hz, this disadvantage did not occur. Since the sound conditions with masking from the ceiling did not produce lower error rates and were not rated as less annoying, these results imply that a local sound masking system can improve the ability to concentrate at work as efficiently as a centralised approach.
Sound Masking in Büroumgebungen Renz, Tobias; Leistner, Philip; Liebl, Andreas
Bauphysik,
06/2019, Letnik:
41, Številka:
3
Journal Article
Recenzirano
Abstract
Sound Masking, sprich das Einbringen eines definierten Geräusches in eine Bürofläche, kann die Störwirkung durch Hintergrundsprache verringern. Konventionelle Sound Masking‐Systeme bestehen ...meist aus in der Decke eingebauten Lautsprechern in einem Raster von 2–4 m. Personalisierte Sound Masking Systeme, bei denen Lautsprecher lokal in Arbeitsplatznähe positioniert sind, sind bislang wenig erforscht. Bei solchen Systemen beeinflusst die Positionierung der Lautsprecher die Wirksamkeit. Der Aufsatz beschreibt die Ergebnisse eines Hörversuchs, der in einem Mehrpersonenbüro in laborähnlichen Bedingungen durchgeführt wurde. Die Versuchsteilnehmer bearbeiteten eine Aufgabe zur Messung der Kurzzeitgedächtnisleistung und einen Fragebogen unter zwölf Schallbedingungen. Die kognitive Leistung der Versuchspersonen war niedriger, wenn das Maskierungssignal und die Sprache aus unterschiedlichen horizontalen Richtungen anstatt aus der gleichen Richtung wiedergegeben wurden. Ein ähnlicher Effekt wurde beobachtet, wenn das Maskierungssignal über ein konventionelles System mit Deckenlautsprechern wiedergegeben wurde. Dieser Nachteil trat nicht auf, wenn die Deckenlautsprecher auch zwischen 100 und 200 Hz Schallenergie abgaben. Da die Maskierung mit konventionellen Deckenlautsprechern weder zu niedrigeren Fehlerraten führte noch als weniger lästig bewertet wurde, kann daraus geschlossen werden, dass das personalisierte Sound Masking‐System genauso wirksam wie das konventionelle System war.
Abstract
Sound Masking in Office Environments
Personalized and conventional systems can increase the cognitive performance: Sound masking, which denotes the specific creation of a background sound field, can reduce the disturbance by irrelevant background speech in open‐plan offices. Conventional sound masking loudspeakers are usually positioned in the ceiling within a grid spacing of 2–4 meters. Personalized sound masking architectures with close‐by sound masking loudspeaker positions are still subject to research. Such systems may depend on spatial masking release, and hence the loudspeaker position may have an impact on the efficiency. This paper reports on a study in an open‐plan office with laboratory‐like conditions. The subjects performed a serial recall task and completed a questionnaire during twelve different sound conditions. With regard to serial recall performance, a disadvantage was observed when the speech and masker signals were presented from different horizontal directions as opposed to the same direction. A similar disadvantage occurred when the masking sound was presented over conventional sound masking loudspeakers that were mounted in the ceiling. However, when the cut‐off frequency of the high‐pass filter that was applied to the masker signal was lowered from 200 to 100 Hz, this disadvantage did not occur. Since the sound conditions with masking from the ceiling did neither produce lower error rates nor were they rated as less annoying, these results imply that personalized sound masking could improve the ability to concentrate at work as efficiently as conventional sound masking.
Sound Masking in Büroumgebungen Renz, Tobias; Leistner, Philip; Liebl, Andreas
Bauphysik,
June 2019, Letnik:
41, Številka:
3
Journal Article
Recenzirano
Sound Masking, sprich das Einbringen eines definierten Geräusches in eine Bürofläche, kann die Störwirkung durch Hintergrundsprache verringern. Konventionelle Sound Masking‐Systeme bestehen meist aus ...in der Decke eingebauten Lautsprechern in einem Raster von 2–4 m. Personalisierte Sound Masking Systeme, bei denen Lautsprecher lokal in Arbeitsplatznähe positioniert sind, sind bislang wenig erforscht. Bei solchen Systemen beeinflusst die Positionierung der Lautsprecher die Wirksamkeit. Der Aufsatz beschreibt die Ergebnisse eines Hörversuchs, der in einem Mehrpersonenbüro in laborähnlichen Bedingungen durchgeführt wurde. Die Versuchsteilnehmer bearbeiteten eine Aufgabe zur Messung der Kurzzeitgedächtnisleistung und einen Fragebogen unter zwölf Schallbedingungen. Die kognitive Leistung der Versuchspersonen war niedriger, wenn das Maskierungssignal und die Sprache aus unterschiedlichen horizontalen Richtungen anstatt aus der gleichen Richtung wiedergegeben wurden. Ein ähnlicher Effekt wurde beobachtet, wenn das Maskierungssignal über ein konventionelles System mit Deckenlautsprechern wiedergegeben wurde. Dieser Nachteil trat nicht auf, wenn die Deckenlautsprecher auch zwischen 100 und 200 Hz Schallenergie abgaben. Da die Maskierung mit konventionellen Deckenlautsprechern weder zu niedrigeren Fehlerraten führte noch als weniger lästig bewertet wurde, kann daraus geschlossen werden, dass das personalisierte Sound Masking‐System genauso wirksam wie das konventionelle System war.
Sound Masking in Office Environments
Personalized and conventional systems can increase the cognitive performance: Sound masking, which denotes the specific creation of a background sound field, can reduce the disturbance by irrelevant background speech in open‐plan offices. Conventional sound masking loudspeakers are usually positioned in the ceiling within a grid spacing of 2–4 meters. Personalized sound masking architectures with close‐by sound masking loudspeaker positions are still subject to research. Such systems may depend on spatial masking release, and hence the loudspeaker position may have an impact on the efficiency. This paper reports on a study in an open‐plan office with laboratory‐like conditions. The subjects performed a serial recall task and completed a questionnaire during twelve different sound conditions. With regard to serial recall performance, a disadvantage was observed when the speech and masker signals were presented from different horizontal directions as opposed to the same direction. A similar disadvantage occurred when the masking sound was presented over conventional sound masking loudspeakers that were mounted in the ceiling. However, when the cut‐off frequency of the high‐pass filter that was applied to the masker signal was lowered from 200 to 100 Hz, this disadvantage did not occur. Since the sound conditions with masking from the ceiling did neither produce lower error rates nor were they rated as less annoying, these results imply that personalized sound masking could improve the ability to concentrate at work as efficiently as conventional sound masking.
Sound Masking in Büroumgebungen Renz, Tobias; Leistner, Philip; Liebl, Andreas
Bauphysik,
06/2019, Letnik:
41, Številka:
3
Journal Article
Recenzirano
Sound Masking, sprich das Einbringen eines definierten Geräusches in eine Bürofläche, kann die Störwirkung durch Hintergrundsprache verringern. Konventionelle Sound Masking‐Systeme bestehen meist aus ...in der Decke eingebauten Lautsprechern in einem Raster von 2–4 m. Personalisierte Sound Masking Systeme, bei denen Lautsprecher lokal in Arbeitsplatznähe positioniert sind, sind bislang wenig erforscht. Bei solchen Systemen beeinflusst die Positionierung der Lautsprecher die Wirksamkeit. Der Aufsatz beschreibt die Ergebnisse eines Hörversuchs, der in einem Mehrpersonenbüro in laborähnlichen Bedingungen durchgeführt wurde. Die Versuchsteilnehmer bearbeiteten eine Aufgabe zur Messung der Kurzzeitgedächtnisleistung und einen Fragebogen unter zwölf Schallbedingungen. Die kognitive Leistung der Versuchspersonen war niedriger, wenn das Maskierungssignal und die Sprache aus unterschiedlichen horizontalen Richtungen anstatt aus der gleichen Richtung wiedergegeben wurden. Ein ähnlicher Effekt wurde beobachtet, wenn das Maskierungssignal über ein konventionelles System mit Deckenlautsprechern wiedergegeben wurde. Dieser Nachteil trat nicht auf, wenn die Deckenlautsprecher auch zwischen 100 und 200 Hz Schallenergie abgaben. Da die Maskierung mit konventionellen Deckenlautsprechern weder zu niedrigeren Fehlerraten führte noch als weniger lästig bewertet wurde, kann daraus geschlossen werden, dass das personalisierte Sound Masking‐System genauso wirksam wie das konventionelle System war.
In this work we demonstrate that extensive testing is irreplaceable for quality improvement of automotive components and the validation of the degree of technical maturity. Measurement results of ...various development samples from Daimler AG are used to show uncovered deficiencies and thus improvements of the components.
The power conversion efficiency of Cu2ZnSn(S,Se)4 kesterite thin-film solar cells is mainly limited by a low open-circuit voltage VOC. In the literature, this low VOC has been amongst others ...attributed to electrostatic potential fluctuations leading to fluctuating band edges. This assignment was mainly based on the observation of a shift of the photoluminescence (PL) maximum to higher photon energies as a function of excitation power, which was interpreted in terms of a screening of the electrostatic potential fluctuations. However, in this paper, we show evidence that the observed shift of the PL maximum is dominantly caused by state filling rather than screening. Our assignment is based on the investigation of the full PL line shape (not only of the PL maximum) and the PL yield as a function of excitation power and temperature. Further support of our interpretation is given by the observation of additional band-tail emission showing up as a second high-energy PL band at the highest excitation powers. The spectral position of this additional band coincides with the absorption-tail deduced from photoluminescence excitation spectroscopy (PLE).
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