The cost-benefit and cost-effectiveness of a work-directed intervention implemented by the occupational health service (OHS) for employees with common mental disorders (CMD) or stress related problems at work were investigated. The economic evaluation was conducted in a two-armed clustered RCT. Employees received either a problem-solving based intervention (PSI; n = 41) or care as usual (CAU; n = 59). Both were work-directed interventions. Data regarding sickness absence and production loss at work was gathered during a one-year follow-up. Bootstrap techniques were used to conduct a Cost-Benefit Analysis (CBA) and a Cost-Effectiveness Analysis (CEA) from both an employer and societal perspective. Intervention costs were lower for PSI than CAU. Costs for long-term sickness absence were higher for CAU, whereas costs for short-term sickness absence and production loss at work were higher for PSI. Mainly due to these costs, PSI was not cost-effective from the employer's perspective. However, PSI was cost-beneficial from a societal perspective. CEA showed that a one-day reduction of long-term sickness absence costed on average €101 for PSI, a cost that primarily was borne by the employer. PSI reduced the socio-economic burden compared to CAU and could be recommended to policy makers. However, reduced long-term sickness absence, i.e., increased work attendance, was accompanied by employees perceiving higher levels of production loss at work and thus increased the cost for employers. This partly explains why an effective intervention was not cost-effective from the employer's perspective. Hence, additional adjustments and/or support at the workplace might be needed for reducing the loss of production at work.

Objectives. Common mental disorders (CMDs) are among the main causes of sickness absence and can lead to suffering and high costs for individuals, employers and the society. The occupational health service (OHS) can offer work-directed interventions to support employers and employees. The aim of this study was to evaluate the effect on sickness absence and health of a work-directed intervention given by the OHS to employees with CMDs or stress-related symptoms.

Methods. Randomisation was conducted at the OHS consultant level and each consultant was allocated into either giving a brief problem-solving intervention (PSI) or care as usual (CAU). The study group consisted of 100 employees with stress symptoms or CMDs. PSI was highly structured and used a participatory approach, involving both the employee and the employee’s manager. CAU was also work-directed but not based on the same theoretical concepts as PSI. Outcomes were assessed at baseline, at 6 and at 12 months. Primary outcome was registered sickness absence during the 1-year follow-up period. Among the secondary outcomes were self-registered sickness absence, return to work (RTW) and mental health.

Results. A statistical interaction for group × time was found on the primary outcome (p=0.033) and PSI had almost 15 days less sickness absence during follow-up compared with CAU. Concerning the secondary outcomes, PSI showed an earlier partial RTW and the mental health improved in both groups without significant group differences.

Conclusion. PSI was effective in reducing sickness absence which was the primary outcome in this study.

Previous research has shown that semantic-based tasks are negatively influenced by semantic aspects in background speech. Collaboration is an important task in open-plan study environments and is a semantic task which might be disrupted by background speech. Therefore, the aim of this study was to analyze the influence of irrelevant background speech on student-collaboration. Participants worked in pairs to solve spot-the-difference puzzles, by using the 'DiapixUK' collaboration task, while they were exposed to different background sound scenarios. The composed sound scenarios varied in semantic content (mother tongue and foreign language background speech)and reverberation time (short vs long), the latter affecting speech intelligibility. Although a longer reverberation time decreases the intelligibility of background speech and a foreign language decreases meaningfulness of speech, no significant changes in performance were found. On the other hand, the data show an increased perceived disturbance for a longer reverberation time, which we interpret as an increased difficulty of interpersonal communication in the collaboration task due to the increased level of the background speech. The quiet reference condition was the most preferred sound condition which is in line with both the effect of a low background sound level and the absence of semantic interference. 

It is not unusual that people have to write in an environment where background speech is present. Background speech can vary in both speech intelligibility and location of the sound source. Earlier research has shown disruptive effects of background speech on writing performance. To expand and reinforce this knowledge, the present study investigated the role of number of voices and sound source location in the relation between background speech and writing performance. Participants wrote texts in quiet or in background speech existing of one or seven voices talking simultaneously, located in front of or behind them. Overall, one voice was more disruptive than seven voices talking simultaneously. Self-reports showed that sound from the front was more disruptive compared to sound from behind. Results are in line with theory of interference-by-process, attentional capture and the cross-modal theory of attention. The relevance of the results for open-office environments is discussed.

Aim

The aim of this contribution is to review parts of the knowledge gathered so far about the effects of background speech on writing performance and to discuss the implications for open-plan offices.

Background

Irrelevant background speech is amongst the most often mentioned sources of annoyance at work and it can impair writing performance. Thus, performance and health are challenged when working in open-plan offices wherein background sound is commonplace. To investigate the effects of irrelevant background speech on writing in a more detailed way, five studies were done. Study one investigated whether the semantic properties of the irrelevant background speech contribute to disruption of writing processes. A follow-up study investigated the relationship between Speech Transmission Index and writing fluency. In study three, Experiment 1 explored the appreciation and effectiveness of several ways of masking background speech. Experiment 2 studied whether background speech from simultaneous talkers (i.e. 3, 5 and 7 talkers compared to 1 single talker) lead to distraction. Study four investigated the combined effects of task interruptions caused by task shifting and task interruptions caused by background speech. The fifth study investigated whether sound source location and inattention could modulate the relation between background speech and writing fluency.

Methods

All studies had experimental within-subject designs. Participants wrote stories while they were exposed to different sound conditions.

Results

Study one revealed that meaningful speech disrupted writing performance compared to meaningless rotated speech and quiet. Study two showed that disruption kicks in with relatively low speech intelligibility. In Experiment 1 in study three, the most effective and appreciated way of masking background speech was with multiple voices and Experiment 2 revealed that performance was worst with 1 background voice and best with 7 voices. Study four showed that it took 10-15 seconds to reach the same writing speed after an interruption as before. In study five, results showed that high inattentive individuals might profit from low intelligible background speech located behind them. Self-reports revealed that speech coming from the front was perceived as more distracting compared to speech coming from behind.

Conclusions

The most important result is that writing fluency is highly sensitive to the intelligibility of background speech. This suggests that the designs of noisy work environments should be adjusted for the tasks that have to be executed. Writing should be done in a quiet environment with minimal risks for task interruptions.

The overall aim of the four experimental studies included in this dissertation was to investigate the influence of background speech on writing performance. In Paper I, a manipulation of speech intelligibility of background speech, by using the Speech Transmission Index (STI), revealed disruptive effects at lower STI values (i.e. with relative low speech intelligibility) than expected, based on an earlier developed model. This showed that writing is more sensitive to disruption from background speech than previously thought.

Experiment 1 in Paper II addressed the question whether the sound of babble, sound of water waves, or pink noise is the most effective and appreciated way of masking background speech to reduce its intelligibility and thereby its disruptiveness. Masking with babble was best. Experiment 2 in Paper II followed this finding up by showing that the disruption of writing by background speech is a function of the number of voices talking in the background—less voices, more disruption.

Paper III investigated the combined impact of background speech and task interruptions on writing performance. Background speech (which was played during the whole condition) after an interruption was expected to prolong the time it took to resume the same writing speed as before the interruption. This hypothesis was not confirmed, but participants’ self-reports showed that the combination of task interruptions and background speech convey a particularly high workload.

Paper IV explored what role sound source location and individual differences (inattention, noise sensitivity and working memory capacity) play in the disruption of writing by background speech. Self-reports showed that speech in front of the individual was perceived as more distracting compared to speech from behind. Other results in the same study showed that high inattentive individuals profit more from less intelligible speech located behind them than attentive individuals and high noise-sensitive individuals were more distracted by highly intelligible background speech than by less intelligible background speech.

The most important and replicable finding in this dissertation is that writing fluency is very sensitive to disruption from background speech; a finding relevant for the design of open work environments. In work areas where writing is a common task, the aim should be to create quiet work areas.

Huvudsyftet med de fyra experimentella studierna som den här avhandlingen omfattar var att studera hur bakgrundsprat påverkar skrivandet av en text. I Artikel I manipulerades taluppfattbarheten (Speech Transmission Index; STI) i bakgrundspratet genom att till olika grad maskera talljudet med ett brusljud. Ljudet spelades sedan upp medan deltagarna arbetade. Resultaten visade att störningarna i skrivprocessen uppträder redan för lägre STI värden (d.v.s. redan vid låg taluppfattbarhet) än vad som förväntades baserad på en tidigare utvecklad modell.

Experiment 1 i Artikel II studerade vilket ljud (babbel, vågor eller brus) som är det mest effektiva och uppskattade för att maskera bakgrundsprat och reducera taluppfattbarhet i bakgrundsprat. Resultaten visade att babbel var bäst. Experiment 2 i Artikel II följde upp det här resultatet genom att visa att störningen från bakgrundsprat vid skrivande beror på antalet personer som pratar samtidigt i bakgrunden - färre röster, mer störning.

Artikel III fokuserade på hur skrivandet påverkas av att det, utöver bakgrundsprat, även finns andra avbrott i skrivuppgiften. Hypotesen var att bakgrundsprat (som spelades upp under hela betingelsen) direkt efter avbrottet skulle öka tiden det tar att nå samma skrivhastighet som före avbrottet. Den här hypotesen bekräftades inte, men deltagarnas självskattningar visade att kombinationen av avbrott och bakgrundsprat leder till en upplevelse av ökad arbetsbelastning.

Artikel IV undersökte huruvida ljudkällans position i rummet, samt individuella skillnader (uppmärksamhet, arbetsminneskapacitet och ljudsensitivitet) modererar hur bakgrundsprat påverkar skrivandet. Självskattningar visade att bakgrundsprat som kommer framifrån upplevs som mer störande än bakgrundsprat som kommer bakifrån. Resultaten visade även att personer som har en låg förmåga att bibehålla uppmärksamheten gynnades mer av bakgrundsprat med låg taluppfattbarhet som kom bakifrån än personer som har hög förmåga att bibehålla uppmärksamheten. Vidare var ljudkänsliga individer mer distraherade av bakgrundsprat med högre taluppfattbarhet, jämfört med lägre taluppfattbarhet.

Det viktigaste resultatet, som även replikerades mellan de olika studierna i den här avhandlingen, är att skrivprocessen är mycket känslig för bakgrundsprat; ett resultat som är relevant vid design av t.ex. öppna kontorslandskap. I arbetsomgivningar där skrivuppgifter är vanligt förekommande, bör tysta utrymmen skapas.