Why filtering out background talk is tiring
The core idea is that ignoring sound is not free. When speech or other interruptions compete with the task in front of you, some of your limited attention has to be spent blocking them out, and that leaves less for the work itself. One study of open-plan office noise frames this as a cognitive-load problem: irrelevant speech was strongly correlated with mental fatigue and perceived workload, and the authors suggest that people may need more mental resources to tune it out [4].
That framing is a proposed explanation rather than a proven mechanism. The same study notes that this added load is a possibility, not something it directly demonstrated [4]. A separate review-style analysis of indoor acoustics argues that the link between sound and work performance runs through mental workload, but concludes that this pathway still needs stronger, multi-level evidence before it can be treated as settled [2].
What the fatigue actually looks like at work
In the controlled office experiment, the effect showed up as both feeling more tired and finding it harder to concentrate, at a noise level close to what many open-plan offices actually produce [1]. That matters because 55 dBA is not a loud industrial roar; it is the level of ordinary office hubbub, which makes the finding relevant to everyday desk work rather than only to extreme conditions.
Field data from academic buildings point the same way. Faculty reported more annoyance and more mental fatigue as measured sound levels rose, and the disturbances they named were the small, intermittent ones — nearby conversation, people walking past, doors opening and closing — rather than a constant loud hum [3]. In that setting, lecture rooms mostly stayed within the 55 dBA benchmark, while hallways on upper floors often exceeded it, with peaks up to 89 dBA [3]. The pattern suggests that unpredictable, speech-like interruptions are the ones that wear people down during focus-heavy tasks.
Does everyone feel it equally?
Not necessarily. One study looked specifically at age-related hearing loss and found that sensitivity to irrelevant speech was strongly tied to mental fatigue and perceived workload [4]. The implication is that people who struggle more to separate speech from background sound may pay a higher mental price for the same office — though this is an association observed in that study, not proof that hearing loss causes the extra fatigue.
The evidence also comes with a scope limit worth keeping in view. Most of these findings rest on self-reported fatigue and annoyance, or on short experimental exposures, rather than on long-term measures of cognitive depletion [1][3]. So the direction of the effect is fairly consistent, but how large it is over a full working week, and how much of it is truly the cost of coping versus simple annoyance, is less firmly established.
Can changing the sound reduce the mental load?
If part of the fatigue comes from effortful filtering, then making the soundscape less speech-like or less intrusive should help — and there is early evidence pointing that way. A study using brain (EEG) and self-report workload measures examined natural sound masking in open-plan offices, treating mental workload as the strain that arises when task demands outstrip available cognitive resources [5]. That work is directly aimed at whether acoustic conditions shift mental effort, but it is recent and the abstract-level evidence does not yet establish how much masking reduces fatigue in real offices [5].
The practical reading is that acoustic fixes are plausible fatigue fixes, not proven ones. Reducing intermittent speech and door noise, or adding masking sound, targets exactly the kind of disruption people name as most draining [3][5]. But the strongest current claim the evidence supports is narrower: poor office acoustics is associated with more mental fatigue during sustained work, and the effort of coping with distracting sound is a reasonable explanation for part of that link [1][2][4].
Sources used in this answer
The effects of moderate heat stress and open-plan office noise distraction on SBS symptoms and on the performance of office work.
Open-plan office noise distraction at a realistic 55 dBA increased fatigue and difficulty concentrating in a controlled office experiment.
When Sound Helps or Hurts: Behavioral and EEG Evidence on the Dual Effects of Indoor Acoustic Environments on Office Work Performance
The paper examines indoor acoustics and office work performance through behavioral and EEG measures, assessing mental workload as a possible link between acoustic conditions and performance, while noting this pathway needs stronger evidence.
Noise pollution effects on mental fatigue and noise annoyance among CEA-MMCM faculty members
In academic buildings, higher measured sound levels were positively associated with faculty-reported noise annoyance and mental fatigue, with conversation, foot traffic, and intermittent disturbances named as the main disruptors.
Noise annoyance in open-plan offices and occupant fatigue: A study on the influence of age-related hearing loss
In simulated open-plan office noise, sensitivity to irrelevant speech was strongly correlated with mental fatigue and perceived workload, with the authors suggesting extra mental resources may be needed to cope.
Neurophysiological and perceptual insights into the benefits of natural sound masking in open-plan offices
Using EEG and NASA-TLX measures, the study investigated how natural sound masking in open-plan offices relates to mental workload and mental strain from task demands versus available cognitive resources.