In open-plan offices, sound masking is often used to lower speech intelligibility and raise cognitive performance of the employees by reducing the irrelevant speech effect. Classic sound masking methods use speakers built into the ceiling of the office to increase the overall background noise level in the office and reduce speech intelligibility. However, the emergence of activity based offices is increasing the need for personalized sound masking methods that are no longer used globally in the office, but can be controlled by each employee individually depending on their activity and, for example, played back through headphones during activities that require particularly intense concentration. The playback of a classical sound-masking noise (e.g. a simple pink noise filtered by -5 dB per octave) via headphones is effective, but not pleasant. For this reason, a new sound-designed masking signal was developed in the present study, which consists of slowly fluctuating binaural harmonic components, as well as atmospheric sounds like water sounds and masking noise. A listening test with a cognitive task and a survey after each test condition showed that the developed signal had a similar positive effect on cognitive performance as a classical masking noise, but was rated as significantly more pleasant.

Distribution and warehouse-type facilities are routinely constructed all over the country and the world. On-site noise sources for this type of facility include heavy trucks, delivery vehicles, and rooftop HVAC equipment. Stationary noise is often more clearly regulated than mobile noise sources. To protect the public, appropriate criteria need to be established for all sources. Some jurisdictions have quantitative regulatory limits in place that may be used as design criteria while others may have less helpful qualitative code language or no noise code at all. A review of common metrics found throughout the U.S. is presented to understand code language that appropriately protects the public for specific sources. In addition, it is useful to analyze and discuss common criteria applied in the absence of quantitative code limits.

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High speech intelligibility in open-plan offices and thus a high changing-state character of the acoustic environment have been found to negatively influence cognitive performance. This is often attributed to the so-called irrelevant speech effect. Office workers lately use active noise-cancelling (ANC) headphones to improve the acoustic situation by blocking unwanted sound. However, it is currently unknown if using ANC headphones in a noisy setting improves cognitive performance. Two studies were conducted to examine if ANC headphones improve cognitive performance and the subjective well-being of employees in an open-plan office. Cognitive performance was measured using a serial recall test. Subjective assessments were measured using a questionnaire. The participants were tested in silence, speech without headphones, speech with ANC headphones switched off and speech with ANC headphones switched on. No statistically significant differences were found between the conditions with ANC headphones switched on and off as well as without headphones for cognitive performance. However, ANC headphones statistically significantly improved subjective assessments such as perceived privacy and the assessment of the acoustic environment. The results provide a scientific basis for evaluating and planning the appropriate use of ANC headphones for concentration-intensive activities such as office work.