PROCEEDINGS of the
23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

Physiological, psychological, and performance effects of officenoise
Jenni RADUN 1; Valtteri HONGISTO1; Henna MAULA1, Ville RAJALA1, Darin AL-RAMAHI2, MikaSCHEININ2
1

Turku University of Applied Sciences, Finland
2

University of Turku, Finland

ABSTRACTBACKGROUND. Colleagues’ speech is a common disturbance in offices, especially in open-plan offices.
Irrelevant speech influences cognitive performance and subjective ratings of acoustic satisfaction as well as
environmental satisfaction. However, only few studies have examined simultaneously physiological,
performance, and psychological consequences background speech has on humans.
AIM. The purpose was to compare psychological experiences, cognitive performance, and physiologicalresponses in two sound conditions: speech and silence.
METHODS. We tested 21 subjects in the speech group and 19 subjects in the silence group (sound level ofventilation 35 dB LAeq). Speech was played at sound level 65 dB LAeq, which people were supposed to ignore
while making cognitive tasks and answering questionnaires. The sound condition lasted on average for 48
minutes. Participants’ performance, psychological experience and various physiological stress reactions (e.g.
stress hormone levels, heart rate variability) were measured.
RESULTS. The speech group had lower performance and higher physiological stress level than the silencegroup. Speech was subjectively estimated more annoying and loading, but less tiring than silence.
PRACTICAL IMPLICATIONS. This study shows that speech influences experience, performance, andphysiological stress level. Therefore, its influence should be minimized in offices, where work requiring
concentration is needed.
Keywords: Irrelevant speech, Stress reaction, Office noise

1. INTRODUCTION

Noise and lack of privacy are the two most important disturbances in open-plan offices (1).
Negative effects of poor acoustic environment in office are for example increased distraction, reduced
privacy, increased concentration difficulties, and increased use of coping strategies (2). Irrelevant
speech is one of the most disturbing type of noise in the office setting, since it has been shown to
influence cognitive work performance and subjective disturbance (3). In addition, working under
office noise can make people to exert, i.e. to put more effort into their task to keep the performancelevel as high as without the noise. Both noise and exertion can cause stress. For example, a study
comparing a typing task in silence and in office noise, which included speech among other noises,
found an increase in adrenaline levels when working under office noise (4). The study found nodifference in typing performance nor in cortisol and noradrenaline levels, but after office noise
condition people tried to solve less puzzles and they made less postural adjustments to their officefurniture (4). Another study examining the influence of office noise found effects on memory of words,
but no other effects on performance or cortisol or norepinephrine levels (5). One more study foundjenni.radun@turkuamk.fi; valtteri.hongisto@turkuamk.fi; henna.maula@turkuamk.fi;
ville.rajala@turkuamk.fi; 2 darin.al-ramahi@utu.fi; mschein@utu.fi
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due to influence of office noise higher exertion in the head and contrary to expectations lower bloodpressure (6).
Speech has been identified as more disturbing for performance than other noise types (7). Not
many studies have examined how working under speech influences performance, psychologicalexperience and physiological stress reaction.
The purpose was to compare psychological experiences, cognitive performance, and physiologicalresponses in two sound conditions: speech and silence. We expect that speech increases stress level,
reduces performance, and increases negative subjective ratings compared to silence.

2. METHOD
2.1 Participants
Forty people participated the study (22 females, age mean 25 years, min. 19 years, max. 37 years).
All participants had normal hearing that was tested in the beginning of the experiment. All participants
gave an informed consent before participating the study. The ethics committee of Hospital District ofSouthwest Finland approved the study (ETMK Dnro 20/1801/2018).
2.2 Sound conditions
There were two sound conditions: silence and speech. Silence was wideband noise presented atsound pressure level 35 dB LAeq . The condition corresponds to typical ventilation sound in open-plan
offices. Speech was a radio dialogue at 65 dB LAeq . Both silence and speech had a one-third-octave
spectrum that was interpolated from the standardized human speech spectrum (8). Silence was on the
background during the whole experiment, except for the speech group, when speech was on during
the experimental phase.
2.3 Participants division into sound conditions
Participants were divided into two experimental groups (two sound conditions) according to theirgender and noise sensitivity (NS) score, which was asked when they registered themselves asvolunteers. NS was measured with Weinstein’s noise sensitivity scale (9). Based on our previous
sample of 184 respondents, we defined the points, which divided observers into three equal groups:
high, middle, and low NS. These points were used to divide the observers equally into different soundconditions. Table 1 presents the participants in different sound conditions in relation to their NS scores.
Table 1 – The number of participants in each sound condition and the distribution of high, middle and low
noise sensitivity (NS) participants. The number in brackets represents participants from whom all blood
samples were successfully acquired.
Sound condition
Silence
SpeechTotal

2.4

High NS4 (4)6 (3)10 (7)

Middle NS Low NS
7 (5)
8 (6)
7 (6)
8 (5)
15 (10)15 (12)Total
19 (15)21 (14)40 (29)Measures2.4.1 Psychological (subjective) measures
After each task, the participants rated how much background sound irritated, bothered or annoyedthem (annoyance) and how demanding or loading performing the tasks was (workload). The scale forboth questions was from 0 “Not at all” to 10 “Extremely”. The perceived fatigue was measured using
Swedish Occupational Fatigue Inventory (SOFI), which gave three scales: tiredness, lack of energy,
and lack of motivation (10).
2.4.2 Performance measures
N-back is a working memory task, where the participant responses whether the current stimulus is
the same as n stimuli back (11). Three difficulty levels were used n = 0, 1, 2, and 3. Each time, 30+n
repetitions of each difficulty level were performed.
Serial recall tasks are also working memory tasks examining how well the participants can keep alist of numbers in their mind. Digits from 1-9 were presented in a random order and participants were2369

asked to write the correct order 10 seconds after the last digit was presented. 11 series were used. Twovariations of the task were used: visual serial recall (VSR), where the numbers were presented visuallyon the display and auditory serial recall (ASR), where the participants heard the numbers fromheadphones.
2.4.3 Physiological (stress) measures
The physiological stress measures used were stress hormone concentration (cortisol andnoradrenaline) determined from plasma, heart rate variability (HRV) measured with a heart ratemonitor around participants’ chest, and blood pressure. Plasma was taken from the peripheral venous
access catheter that was placed in participants’ arm in the beginning of the experiment. From HRV,
the LF/HF relation was determined. It describes the activity of parasympathetic and sympathetic
nervous system. The larger values mean greater sympathetic nervous system activity, which means
more stress. This relation is here called HRV LF/HF, which was calculated for periods of each cognitive
task separately (VSR, ASR, and N-back).
2.5 Procedure
Procedure is described in Figure 1. Silence (35 dB ventilation sound = silence) was present in theroom in every phase except in the experimental phase where the actual sound condition (silence or
speech) was presented.
The experiment started at 11.45 each day and lasted on average for 3 h 19 min. Afternoon waschosen because diurnal variation in cortisol concentration is the largest in the morning. In the
preparation phase, first the heart monitor and then the catheter were put on and hearing was tested.
This was followed by the practice phase, where all tasks were explained and rehearsed. The baseline
phase and experimental phase involved the same cognitive tasks and subjective estimations but theexperimental sound was presented only in the experimental phase (silence or speech). Two participants
were tested at the same time. The blood samples were taken 6 times during the experiment. Bloodpressure was measured each time after taking the blood sample. In the questionnaire 1 (Q1),
participants reported their current state and other background information. Psychological estimations
related to sound were estimated several times during the experiment. Annoyance and workload were
estimated after each task (8 times) (IQ1 and IQ2) and SOFI was filled each time after N-back task (4times) (IQ2). In the restoration phase, participants filled questionnaires (Q2 personality and Q3 finalquestionnaire) with the silence in the background. The results from these two last questionnaires will
not be reported in this article.
2.6 Statistical analysis
To reduce the influence of individual differences, the difference between experimental phase andbaseline phase was estimated for the psychological and most physiological measures (experimental
phase – baseline phase). However, cortisol concentration showed the expected diurnal changes incortisol levels, but also there seemed to be large differences possibly due to excitement in the baseline
phase. Therefore, with cortisol we used the restoration phase measurement as the reference(experimental phase - restoration phase). The performance measures showed more variation in
performance in the baseline phase than in the experimental phase possibly due to excitement of theexperiment as well as learning the tasks. Therefore, we examined the performance measures with adirect between groups comparison without comparing them to baseline performance.
The groups were compared with each other using repeated measures analysis of variance, if theexperimental phase had more than one observation from each participant on that variable. In thosecases, time was the within-subject variable, sound condition was the between-subject variable andnoise sensitivity was the covariate. If there was just one observation on that certain variable from theexperimental phase, then univariate analysis of variance was used with sound condition as the
between-subject variable and noise sensitivity as the covariate. From the performance measures of Nback task, only 3-back is reported here, since it was the only that filled the requirements of repeatedmeasures analysis of variance. Greenhouse-Geisser correction was used, if the sphericity assumptions
were not filled (ASR and VSR interaction).

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S tage/ Time Task
0 min Recruitement questionnaire
Preparation
phase

Informed consent
Putting on catheter and heart rate monitor

30 min Hearing test
Practice phase

Questionnaire 1 (Q1)
Visual serial recall
N-back25 min Auditory serial recall
Baseline phase

Visual serial recall
Intermediate questionnaire 1 (IQ1)
N-back (Time 1)
Intermediate questionnaire 1 (IQ1)
Auditory serial recall
Intermediate questionnaire 1 (IQ1)
N-back (Time 2)

50 min Intermediate questionnaire 2 (IQ2)
10 min BreakExperimental
phase

Visual serial recall
Intermediate questionnaire 1 (IQ1)
N-back (Time 1)
Intermediate questionnaire 1 (IQ1)
Auditory serial recall
Intermediate questionnaire 1 (IQ1)
N-back (Time 2)

50 min Intermediate questionnaire 2 (IQ2)
Restoration phase Questionnaire 2 (Q2)
20 min Questionnaire 3 (Q3)
Wholeexperiment: 3 h
20 minTaking off catheter and heart rate monitor
Receiving the reward
End

Figure 1 – The procedure of the experiment. Red lines denote when the blood sampling took place and thegrey area when the experimental sound was on.

3. RESULTS

Psychological measures are reported in Table 2, where the numbers describe the difference between
experimental and baseline phases. Therefore, the results report whether the experimental phase wasestimated differently between the sound conditions, when taking into account the baseline phase.
Speech was considered more annoying than silence (F(1,37)=33.0, p<0.001). Workload was larger inspeech (F(1,36)=8.6, p=0.006). Unexpectedly, tiredness was larger in silence (F(1,37)=10.0, p=0.003).
Performance measures are reported in Table 3. In auditory serial recall task, the last numbers weremore difficult to remember during the speech than during silence (F(4,152)=5.2, p=0.001) (Figure 2).
In visual serial recall, there was no similar effect (F(5,170)=1.4, p=0.247). In addition, theperformance accuracy was lower in 3-back task during speech than during silence (F(1,37)=5.1,
p=0.029).
Table 4 shows the results of the physiological measures. Again, the numbers in Table 4 describe
the difference between experimental and reference phases (either the baseline phase or the restoration
phase) to reduce individual differences. The results report whether measurements in the experimental

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phase were different in the sound conditions, when taking into account the reference measurement.
The difference in cortisol levels between the restoration phase and the experimental phase was higher
in speech than silence (F(1,27)=4.3, p=0.048). Two physiological measures, noradrenaline and
HRV LF/HF, showed different interaction depending on the sound condition in relation to time. With
time, noradrenaline level in the silence condition increased, while it stayed steady in the speech
condition (F(1,29)=7,8, p=0.009) (Figure 3). N-back was the only task that was done twice during theexperimental phase, which enables the examination of time in HRV LF/HF. From first to second N-backtasks, HRV LF/HF increased in speech, while the value stayed the same in silence (F(1,35)=6,2, p=0.018)(Figure 4). This indicates that stress increased with time during speech.
Table 2 – The difference between psychological estimations in the baseline phase and the experimental
phase. Negative value means that the value is higher in the baseline phase. Positive value means the
opposite.

Sound condition
Speech(mean)

Variable

Silence
Reference phase (mean)

Annoyance***

Baseline

0.18

4.91

Workload**

Baseline

-0.35

1.03

Tiredness**

Baseline

0.57

-0.75

Lack of energy

Baseline

0.35

0.49

Lack of motivation

Baseline

0.14

-0.27

*p <0.05; **p <0.01; ***p <0.001

Table 3 – The difference in performance accuracy [proportion of correct answers (PCA)] between soundconditions.

Sound condition
Variable

Silence(mean)

Speech(mean)

Auditory serial recall (ASR) x

0.59

0.52

Visual serial recall (VSR)

0.59

0.56

3-back *

0.89

0.84

*p <0.05; **p <0.01; ***p <0.001
x=The interaction between background noise and position was
significant.

Figure 2 – The proportion of correct answers (PCA) per position of the digit for the two sound conditions inauditory serial recall task (ASR). The error bars denote the 95% confidence interval.

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Table 4 – Physiological measures in the two sound conditions. The means show the difference between thereference phase and the experimental phase. If the value is negative, the value in the reference phase ishigher. If the value is positive, the value is higher in the experimental phase.

Sound condition
Variable

Silence
Reference phase (mean)

Cortisol [nmol/l] *Restoration

Speech(mean)

-8.62

36.56

Noradrenaline [nmol/l] x
Baseline
Systolic blood pressure [mmHg] Baseline

0.22

0.02

2.90

0.83

Diastolic blood pressure [mmHg] Baseline

-0.49

-0.85

HRV LF/HF ASR
HRV LF/HF VSR

Baseline
Baseline

-0.28
-0.06

0.15
-0.32

HRV LF/HF N-back x

Baseline

-0.13

0.04

*p <0.05; **p <0.01; ***p <0.001
x=The interaction between background noise and time was significant.

Figure 3 – Interaction for noradrenaline levels and time for the two sound conditions. The values represent
the averages of the difference between the measurements in the baseline phase and the experimental phase.

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Figure 4 – Interaction for HRVLF/HF N-back and time for the two sound conditions. The values represent the
averages of the difference between the baseline phase and the experimental phase.

4. DISCUSSION

Working in speech influences performance, psychological experience, and physiological stressmeasures. Speech was estimated more annoying and loading than silence, but it was also estimated asless tiring than silence. This might be due to the energetic radio dialogue used as speech. In speech
condition, remembering the last words in auditory serial recall task was harder than in silence andthe accuracy of 3-back task was lower. The decrease in performance due to speech is in line with otherresearch (7). Absence of the effect of sound condition on performance in visual serial recall was
unexpected, since some studies have found an effect of speech on performance during visual serial
recall task (12,13).
Speech increased cortisol levels. Previous research has found no effect of office noise on cortisol
levels (4–6). However, in these studies, the background sound was office noise that contained only
some speech, and in this study, speech involved an entire radio program (continuous dialogue). In
addition, the level of speech was higher in our study than in previous studies (4) and (5), 55 and 51
dBA, respectively. Contrary to expectations, there was a statistically significant interaction innoradrenaline levels and time; however, we interpret the effect to be so small that it is not
physiologically significant. The stressfulness of speech with time can be seen in HRV LF/HF N-back,which level rises with time during speech but not during silence.

5. CONCLUSIONS

Irrelevant speech corresponding to the sound level of normal conversation is considered annoying
and loading, it decreases performance at least in tasks requiring cognitive working memory processing,and produces physiological stress reaction. With time, these effects can be harmful for employees’
health and motivation. For these reasons, special attention should be given for reducing speech noise
in offices. For this reason, Finland has set new building regulations concerning e.g. the room acoustic
target values in open-plan offices (14).

ACKNOWLEDGEMENTS

The study was part of Anojanssi –project, which was funded by Business Finland, Turku Universityof Applied Sciences, Ministry of Environment Finland, Ministry of Social Affairs and Health Finlandand collaborating companies and associations.

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