Summary: Meaningful sounds such as speech and music can impair performance on cognitive tasks, while meaningless noise tends to be less disruptive, a new study reports.
Source: Acoustical Society of America.
Researchers also measured how annoying listeners found different types of noise.
Open-plan offices are increasingly common because they can maximize space and encourage collaboration. Yet a recent study indicates that hearing meaningful conversations or music can be more disruptive to coworkers performing concentration-heavy tasks than hearing random, meaningless noises. The research, led by Takahiro Tamesue of Yamaguchi University in Japan, was presented at the 172nd Meeting of the Acoustical Society of America and the 5th Joint Meeting with the Acoustical Society of Japan (Nov. 28–Dec. 2, 2016, Honolulu).
The investigators set out to compare how meaningful and meaningless sounds affect selective attention, cognitive performance, and subjective annoyance. They used well-established experimental methods to measure behavior, self-reported annoyance, and brain responses while volunteers completed attention-demanding tasks.
Experiments relied on the oddball paradigm, a common test of selective attention and information processing. In this approach, participants detect and count rare target events embedded within a sequence of repetitive events. Successfully performing the oddball task requires focusing attention on the relevant stimuli and filtering out distractions, making it useful for studying how background sounds interfere with cognition.
In one set of trials, participants completed a visual oddball task. They watched images flash on a computer monitor while sounds played through headphones. Meaningless sounds were modeled as pseudo voice-noise (pink noise shaped to resemble the spectral profile of speech), while meaningful sounds included male and female speech and music. The most common image was a 10 x 10 cm green square; the rare target image was a red square. Subjects counted how many times the red square appeared over a 10-minute period.
In another set of trials, an auditory oddball paradigm required participants to detect and count an infrequent 2,000-Hz tone among frequent 1,000-Hz tones. After each trial, participants rated how annoying they found the background sound on a seven-point scale.
Throughout the experiments, researchers recorded participants’ brain activity using scalp electrodes to capture event-related potentials (ERPs). They focused on two ERP components commonly associated with sensory processing and attention: the N100, which peaks roughly 100 milliseconds after a stimulus and reflects early sensory analysis, and the P300, which peaks around 300 milliseconds and is tied to perceptual decision-making, selective attention, and working memory.
Results showed that meaningful sounds—speech and music—produced higher annoyance ratings than meaningless sounds and led to larger declines in performance on tasks requiring memory or arithmetic. EEG recordings mirrored those behavioral effects: meaningful speech in the background was associated with reduced amplitudes in P100 and P300 components, indicating that selective attention and the allocation of cognitive resources were disrupted. The impact was especially pronounced in the auditory oddball tests, where the presence of meaningful noise more strongly interfered with detecting the target tones.
These findings suggest that when designing acoustic environments for workplaces, schools, and other spaces where focused cognitive work occurs, it is important to consider not only overall sound level but also the meaningfulness of likely background noise. Conversations and other intelligible sounds can be especially distracting because they capture attention and compete with ongoing cognitive processing. Because fully soundproofing open-plan areas is often impractical, the researchers note that solutions which reduce the intelligibility of speech—such as targeted masking or acoustic treatments that lower speech clarity—may help create more comfortable, productive environments.
Source: Acoustical Society of America
Image Source: NeuroscienceNews.com image used for illustration.
Original Research: Presented at the 172nd Meeting of the Acoustical Society of America in Honolulu, Hawaii.
Acoustical Society of America. “Hearing ‘Meaningful’ Sounds Decreases Performance on Cognitive Tasks.” Neuroscience News. December 4, 2016.
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