Irrelevant speech, or background conversations, has been shown to impair cognitive performance and cause physiological stress. Recently published research demonstrated that working during task-irrelevant speech not only increases stress, as measured by heart rate variability, and reduces accuracy but also increases annoyance and perceived workload.
Method
Thirty participants performed two cognitive tasks (n-back and serial recall) in two different sound conditions: irrelevant speech (50 dB) and quiet (33 dB steady-state noise). The study examined how these conditions and their order affected performance, subjective experience, and physiological stress.
The n-back test is a test of working memory and attention. It involves showing a series of stimuli (such as letters, numbers, or images) to the participant and asking them to say whether the current stimulus matches the one shown “n” steps earlier. For example, in a 2-back test, participants track a series of stimuli and say whether the current stimulus matches the one shown two steps back. The n-back test tests working memory and attention, so it can be used to assess cognitive abilities, particularly concentration and information processing speed.
Results
The results showed that working during irrelevant speech compared to quiet reduced accuracy in the serial recall task. Participants found working during irrelevant speech more annoying, reported higher perceived workload, and were less satisfied with the sound environment. The study also found higher physiological stress, indicated by faster heart rates and changes in HRV.
The order of conditions showed additional effects. When speech was the first condition, 3-back performance was less accurate, and serial recall response times were longer. Heart rates were faster, and successive heartbeats had less variability during speech than during quiet. When quiet was the first condition, heart rate was faster, and reaction times in the 3-back task were slower during quiet than during speech.
This research demonstrated that compared to working in quiet, working during task-irrelevant speech reduced accuracy in verbal tasks, increased annoyance and workload, and created a less pleasant sound environment. Participants felt that speech disturbed concentration, impaired performance, and hampered efficient working. These findings are consistent with previous studies on the impact of speech on performance and stress.
Physiologically, working during speech led to lower HRV HF and higher HR, HRV LF, and HRV LF/HF ratios compared to working in quiet. These measures indicate higher physiological stress levels. The frequency-domain analysis of HRV showed that the additional strain is associated with working during irrelevant speech, demonstrating that this strain is not solely related to performing tasks compared to resting.
This study shows that HRV is a suitable measure for stress related to task-irrelevant sounds, at least during short-term exposure in laboratory settings. The research identified two key findings: the performance decline associated with irrelevant sound, evidenced by reduced accuracy in the serial recall task, and alterations in HRV frequency-domain analysis suggesting heightened stress levels.
Importance for office employees
This research is particularly important for office employees. In modern open-plan offices, background conversations are a common source of distraction and stress. Employees are frequently exposed to such noise, which can impair their performance and productivity. Understanding how irrelevant speech affects performance and stress levels can help in designing better work environments.
Reducing speech noise in offices can significantly improve employee well-being, concentration, and efficiency. By using findings from this study, employers and office designers can implement effective noise management strategies, such as sound-absorbing materials, screens and zoning, to mitigate the negative impacts of irrelevant speech on employees. This not only enhances individual performance but also contributes to a more productive and less stressful work environment.
Source: J. Radun, H.Maula, I-K Tervahartiala, V. Rajala, S. Schlittmeier, V. Hongisto “The effects of irrelevant speech on physiological stress, cognitive performance, and subjective experience – Focus on heart rate variability”, International Journal of Psychophysiology, June 2024
