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

Staff experience of sound environment in operating rooms built with non-absorbing
modules
Maria QUINN 1
2

Saint-Gobain Ecophon, Sweden

ABSTRACT
Modular solutions for operation rooms made of glass and metal adversely affect the sound environment as theabsorption of sound is non-existent. The requirement for Reverberation Time (T20) in operating rooms isaccording to Swedish Standard 25268 < 0.6 seconds. Modules without additional acoustic supplement arecalculated to around 2.0 seconds.
In our research the modular ceiling was replaced with an Absorption Class A ceiling according to ISO 11654.
Both normal sized rooms (65m²) and the Hybrid room (105 m²) were treated with absorbents. To gain better
understanding on the sound environment we also measured Speech Clarity (C50) in addition to reverberation
time. All acoustic requirements were fulfilled and this paper aim to evaluate how the staff perceives the soundenvironment in these rooms. Information will be obtained by questionnaires sent to 78 staff at Sundsvall
hospital. The hospital performs 11000 procedures a year in 15 operating rooms. Procedures contains ofcommon surgical, gynecological and orthopedic operations, as well as hernias, cancer, ear-nose-throat andfractures. Operating times varies from short to long and staff alternates within all procedures, the unit is open
during evening and night for emergencies. Questionnaire consists of both multiple-choice and open
questions.
Keywords: Operating room, Staff, Sound environment

1. INTRODUCTION
Noise levels have steadily increased in hospital over the last >40 years, both day time and nighttime (1). The noise level in operating rooms can be particularly difficult and research shows tha t thismay affect the ability of the staff to perceive proper oral instruction; it also affects their perceived
stress and well-being. Sound peaks can reach 110dB when saw and drill are in use (2). Kracht,
Busch-Vishniac and West showed, in a study from 2007 in Johns Hopkins Hospital, that orthopedic
surgery was found to have the highest L eq at approximately 66dB(A). Neurosurgery, urology,
cardiology and gastrointestinal surgery followed closely ranging from 62 -65dB(A). For neurosurgery
and orthopedic surgery peak levels exceeded 100dB over 40% of the time (3).
Medical errors due to noise are a safety concern that needs to be prevented in all possible ways.
Staff reports that they find it difficult to properly hear what is being said and misunderstanding s, due
to reduced intelligibility, is a common problem (4). Misunderstandings might not be of life threatening
sort but seem to delay procedures such as that the wrong size of requested material is collected fromoutside the operating room (2).
It can also be difficult to determine the origin of alarm signals from the technical devises due toreflection of the soundwaves between walls, floor and ceiling. Assessment of distance and direction isvery well developed for the human ear in a setting without disturbing reflexes but it will be negatively
affected in a confined space with multiple sound sources.
What can be done to reduce noise? It requires a combination of actions; use of sound absorbing
materials to deal with excess sound energy and unwanted reflectio ns, functional and operationalsounds from the medical technical devices as well as their alarm sounds and settings together with1
2

maria.quinn@ecophon.se
www.ecophon.com/se

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alteration of human behavior (5). Sound absorbing material can improve the sound environment asshown in several studies and the effect has impact on both staff work environment, wellbeing andstress as well as patient experience of received care (6, 7).
In this building project, the client had chosen a complete package solution for the operating rooms
with a modular solution that enables great flexibility for future changes in the building. All thetechnology and displays available on the wall surface are integrated in the module unit. This gives
maximum use of surface and is functional and hygienic. The visual impression of the room is beautiful
and perceived as pure and aesthetic and building time is heavily reduced and often enable the ongoingwork in other operating rooms to continue without much negative affect from the building area as withtraditional building work. However, there is a disadvantage of modular solutions; floors, walls andceilings adversely affect the sound environment as the absorption of sound is more or less non -existent.
This is due to the module material properties of glass and metal, which instead of decreasing thereverberation time instead contribute to increase it. The requirement for reverberation time inoperating rooms is according to Swedish Standard 25268 0.6seconds or lower (8). Verification thatthese requirements have been met can be achieved in one of two ways. Either an acousticalmeasurement according to SS 3382-2:2008 (9,10) or a calculation of the values in conjunction with aninspection of the building site.
With the building materials used and the shape of most room types we find that sound waves arebeing reflected back and forward with very little sound absorption and decrease of the sound energy.
Hard, reflective materials affect sound in a non-desirable way and sound pressure level is far
exceeding the World Health Organization limit of L eq 35dB(A) (11). The metal ceiling included in themodular package (Hospitaltechnik, DE) was decided to be replaced by a sound absorbing ceilinginstead. The same grids and original measurement for the ceiling tiles was used. The product chosen
was a glass wool mineral absorbent Ecophon Hygiene Performance™ 40mm (Saint-Gobain Ecophon,SE) with Absorption Class A, α w 1,0 (12,13). The absorbent fulfill all cleaning requirements for highspecialist area (methods, cleaning agents and disinfection according to national practice). Absorption
Class A is the highest class and has a very good ability to absorb sound energy. It was used as acomprehensive ceiling solution with the exception of the Laminar Air Flow (LAF) ventilation,pendants and lighting, giving coverage of approximately 80% of the total ceiling area. No absorbents
were mounted on the wall. Reverberation time (T20) was measured to 0,6seconds after the ceiling had
been installed
Sundsvall Hospital is a Regional hospital with approximately 11000 visits/year. It consists of 15
operating room of 65m2 where all but one has advanced ventilation, laminar air flow (LA F). The
Hybrid operating room of 105m 2 has been used as a normal operating room during the first year after
installation and the hybrid usage started after the collection of answers in this survey. Procedures
contains of common surgical, gynecological and orthopedic operations, as well as hernias, cancer,
ear-nose-throat and fractures. Staff rotates in all rooms and work with all procedures mentioned. The
majority of procedures are planned ahead but emergency procedures are a part of the weekly work andcan also be done during late evening and during the night. Operating times varies from short tomedium and long. Staff normal working hours are either 8,5 hours or 9,5 hours per shift, during thenight shift another five hours of on call duty is added. A lunch break of 45min is mandatory and thestaff can leave the operating department during that time. In the operating room all operating staff
wears a full head coverage and mouth protection, anesthetic and assisting staff only have the haircovered.
The staff consists of 28 registered operating nurses, 32 registered anesthetic nurses, 18 assistingnurses and a fluctuating number of surgeons. Surgeons are not included in this survey. All 78 nursing
staff have been employed more than two years meaning that they worked in the previous
non-refurbished operating rooms and have experience of a different working environment. The survey
consists of 13 multiple choice questions and one question with a possibility to add comments in freewriting.

2. METHOD
The survey consists of three more general questions around the sound environment in the operating
room with a four scale answer possibility (such as does the sound environment affect the patients
wellbeing). Followed by eight question with a specific aim towards different issues (such as ability tohear the direction of a sound source) with a three scale answer possibility. Nest question is a multiple
choice question that includes human speech, technical equipment and sounds from the room (such as

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ventilation, opening of doors). The technical equipment question was presented as operating sounds(such as engine, fan), functional sounds (such as suction, sawing) and alarm sounds (such as bloodpressure, heartbeat). The following question regarded their function and placement in the room where
they stated if being part of the operating team or the anesthetic team. Next question asked if they had
been employed at this department for more or less than two years. Last question was and open question
where the respondents could express any comment in free text.
All 78 staff were invited to take the survey during a four-week period in February and Mars 2019.
Surveys was distributed by the department manager to their individual post boxes with an introduction
letter explaining the reason for the survey and the contact details to the author. Surveys wereanonymous and respondent were to place it in a common envelop that was posted to the author at thefinishing date. The collection of data could have been performed digitally but the department manager
believed it would be less work for staff to fill in the paper as they had very limited time accessing acomputer. In total we received 30 answers and they were processed in a digital tool for numericalpresentation and graphs.

3. RESULT
30 answer were received and 15 came from the operating staff, abbreviated OR in the following text,
and 15 from the anesthetic staff, abbreviated AN. All respondents have worked in the ward since
before the reconstruction i.e. more than 2 years. Most staff have worked there for many years and theturnover on staff is low. In the free field to comment five comments where received, four out of thosewere from the AN staff.
Q1: Does the sound environment have an impact on your ability to do a good job? The soundenvironment seems to be of significance as 90% answered very important (43.3%) and rather
important (46,7%) to this question but two respondents from the AN staff thought it had very little(6,7%) significance.
Q2: Does the sound environment affect how the patient feels? When turning the focus towards thesignificance of the sound environment for the patience wellbeing, the importance is expressed as very
important (33,3%) and rather important (40%) with a total of 73,3%. Meaning that 1/3 of the staff
didn´t think the sound environment had much importance for the patient during surgery. There was nodifference between the answers from OR and AN staff.
Q3: How do you experience the sound environment in general in the operating room? The staff
seemed very content with the sound environment in general in the operating room. Very good (17,2%)
and good (65,5%) gives a total of 82,7% that is happy with the present environment. Five peopleanswered poor (17,2%) but no one answered very poor (0%). There were more staff on the OR teamanswering that it was poor (24,1%) than on the AN team (13,3%). Only one of those (AN) left acomment in the free text box about the functional sound of gas extraction. Comparing to the previous
enquire (14) with a total of 154 staff (mixed OR and AN) the overall perception of the soundenvironment scored more positively in this survey. The previous one scored very good 0%, good 16,7%,
poor 71,3%, very poor 12%. Overall positive responses.
Q4: The sound environment affects my well-being? Only one person (3,3%) didn´t think that thesound environment affected their wellbeing at all. 63,3% thought it had an impact (agree fully) and
33,3% answered that it partly had an impact. The OR staff scored 80% on agree fully and 20% on agree
partly as to compare with AN staff scoring 46,7% on both.
Q5: It is easy to perceive speech in the operating room. Roughly half of the respondents choose themiddle alternative agree partly to this question. 11 out of 30 people thought it was easy to hear spoken
communication, fully agree (36,7%), and 3 out of 30 did not agree at all (10%). The groups did not
differ much on this question. Comparing to our previous enquire (14) the respo nses agree fully hasrisen from 11% to 36,7% and the do not agree has fallen from 22% to 10%!
Q6: The sound environment feels comfortable? The majority agreed fully that the soundenvironment felt comfortable (26,7%) or agreed partly (66,7%) with a total positive score of 93,3%.
There was a slight overweight to the fully agree in the AN group. Two people did not agree at all andchoose the do not agree option. The overall difference between the two groups may be connected toboth work tasks and placement in the room as the possible disturbances differs somewhat as shown in
Q11.

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Q7: It is easy to hear where the sound is coming from. The majority of answers (67,7%) agree
partly, 30% agree fully and one person (3,3%) does not agree at all. Comparing the two groups the AN
staff were more positive on being able to determine the direction of the sound source as shown in
Figure 1.

Figure 1 - Q7: It is easy to hear where the sound is coming fromCould this be that they primarily have their focus on the sounds coming from the medical technicalequipment located in their zone in the operating room? The direct sound reaches them with no
obstacles interfering? Comparing with the previous enquire (14) the fully agree group has risen from
11% to 30% and the do not agree at all lowered from 21% to 3%!
Q8: The sound environment makes it easy to concentrate. Only 6,7% answers fully negatively withdo not agree at all. 30% are positive (agree fully) and a large section of 63,3% says agree partly. Therewas very little difference between the two groups. There is however a striking difference to theprevious enquire (14) with the agree fully rising from 10% to 30% and an even larger shift in the do notagree with a decrease from 52% to 6,7%. The staff in this survey found it considerable more easy toconcentrate.
Q9: The sound environment sometimes causes us to misunderstand each other. 13,3% (four people)
answers do not agree, but the majority of answers agree partly meaning that 67,7% relate the soundenvironment to the risk of misunderstandings occurring in the operating room. 20% agrees fully thatsuch misunderstandings may be related to sound. There is no difference between the two groups. As acomparison to the previous enquire (14) the perceived risk of misunderstanding has fallen from 83% to67,7%. The fully agree has halved from 41% to 20%.
Q10: The sound environment feels good even when we are many and have a stressful shift. The
agree fully (20,7%) and do not agree (17,2%) shows two opposite answers very distinctly with the restchoosing the mid-alternative agree partly. Sub diving it shows that OR staff feel more affected whenwork conditions are more strained and more staff are present in the room. Their do not agree scores
26,7% as compared to the AN that only scores 7,1%. Understanding this may be expla ined by thenature of the work, if the stress level increases it might be more likely that it is on the OR side of theprocedure there is a complication and need for more staff and quick decision and handling of more
instruments?
Q11: What type of sounds are disturbing? Human sounds such as speech is seen as disturbing by
44,8% of the respondents, AN staff had a slightly higher score than OR. Machine made sounds are
divided into three categories where the operating sounds (such as engine or fan) is seen as disturbing
by 89,7% and functional sounds (such as suction, sawing) are seen as disturbing by 93,1% of the staff.
Alarm sounds (such as for heartrate or blood pressure) scores lower with 51,7% as shown in Figure 2.
Other sounds in the room (such as ventilation or closing doors) rate the lowest of 17,2%. In both total
score and divide into the two groups, functional sounds by the machines are the most disturbing noise.
27 out of the 29 respondents ticked this option in the survey. OR staff were not as distur bed by alarmsounds and other sounds in the room as the AN staff. Possibly related to their placement in the roomand distance to the technical equipment as well as often having their back against the room facing thesurgical site?

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Figure 2 - Q11: What type of sounds are disturbing?
Q12: Your professional role. 50% of the respondents was part of the Operating (OR) team and 50%of the Anesthetic (AN) team. The assisting nurses was part of the OR team.
Q13: How long have you been working at the operating ward in Sundsvall. All of the respondents
had worked in Sundsvall for more than two years. All staff had experience working in the previous,
older localities to compare with the newly built operating rooms.

4. DISCUSSION
The staff in this survey seem to share the same view as operating staff in general; that the soundenvironment affects both their ability to perform well at work and that it has an impact on thewell-being of the patients. They show great contentment with the general sound environment in th e
newly built modular operating rooms and have expressed that they clearly both felt and heard a
difference in sound manifestations. The sharpness of sounds is described to have been softened and theclatter less apparent.
The main findings in this survey would be that it seems easier to perceive speech in the newly built
operating rooms compared to the country average in previous results (Q5). It also seems as if it iseasier to determine the direction of the sound source (Q7) even though ears are fully co vered during
procedures, possibly affecting the ability to determine the direction and the dist ance to the soundsource (15). In addition to this, the inner circle of staff in the sterile zone will by default have theirbacks toward most other staff in the room, thus affecting their ability to practice both lip-reading andvisually overlook the whole room and the actions done by other staff. Speech Clarity (C50) in theoperating rooms are measured to 5,6dB(A) which correlates well with the optimal values for goodspeech communication, normally considered 6-10dB(A). C50 are likely to rise as well when there are
more people and equipment in the room during a procedure. The combination of a C50 of 5,6dB(A)and a reverberation time (T20) of <0,6 seconds was thought to be favorable values for the perceptionof a good sound environment and ability to interpret human speech. But interpretation of sound is
individual and the perception of what is considered noise can vary as it is dependent on more factors
then sheer combination of mathematical numbers.
Noise also affects our cognitive response and influences our ability to concentrate, our short term
memory, level of fatigue and motivation to “go the extra mile”. These effects of sound are not always
taken into proper consideration when designing the operating room even though it is known thatmisunderstanding in oral instructions is common (2,16) The positive results in Q7 implicates that the
newly built modules with sound absorbers improved this acoustical challenge. Results from Q8
implicates that it is easier to concentrate in the newly built operating rooms compared to an average as
the agree fully tripled and the do not agree fell from 52% to 6,7% (14).
Most disturbance comes from the technical equipment where the functional and operative sounds
are considered the most annoying, followed by the alarm sounds and human speech. Manufacturers
should be advised to pay close attention to these sounds and these sound parameters should beconsidered in tenders as well. Insulation, cooling, length of tubes and pipes may be altered for lessdisturbance. Alarm sounds can in some cases be replaced or combined with other ways of calling for7837

the anesthesiologist attention. Q9 brings attention to the cause of misunderstanding due to the soundenvironment and there is substantial lowering of the perceived risk compared to previous results.
Additionally, staff also expressed that patients often comment on how quiet, calm and soft the soundenvironment is in the operating room and the adjacent corridor.
Highly specialized localities such as the operating room often have ventilation systems thatgenerally add to the sound pressure level but also cause disturbances in ability to interpret speech andalarm signals due to unwanted sound wave reflections from hard surfaces (3). Sound disturbances fromthe advanced ventilation system are often mentioned as disturbing but this did not occur at all in thissurvey. The option of sounds generated by ventilation or other additional sounds like doo r closing
scored low (CRC Medical, SE). However, we find that a large amount of unwanted sounds come fromthe technical equipment. This part of the problem needs to be addressed by the manufacturers of thedevices and proper acoustic demand set in tenders so that the purchase of each device is put in context
with the rest of the sound producing devices (Q11). Human behavior also contributes to which soundor noise level will be dominant in a situation. Most people agree that necessary verbal information is anatural part of the work environment but some people are more sensitive to other unnecessary
conversations, some would like music to be played in the operating room whereas some see it asunwanted sounds e.g noise.

5. CONCLUSIONS
The results showed that the sound environment has importance for the nurse ’s possibility to
conduct their work in a good manner in the operating room. There can be a challenge in interpreting
where different sounds are coming from and considering that the support mechanism as lip reading arelimited due clothing requirements, and the ears of the staff normally are covered, room condition needs
to be optimally acoustically prepared. The risk of misunderstanding should not be neglected and an
operating room with the required reverberation time (T20) of 0,6 seconds should be met. In
conjunction with measured speech clarity it might be easier to determine how the sound environment
will be perceived by the staff? It would be interesting to compare staff perception in operating rooms
with higher and lower C50, it might be a good indicator for future building recommendations? These
operating rooms were acoustically treated with 40 mm absorption class-A products, normally themodular concept consists of a metal ceiling with more or less no sound absorption. Comparing theresults in this survey with the average of the previous enquire, implicates that improvement can bemade from existing operating rooms and modular constructions, were the metal ceiling is replacedwith sound absorbing tiles, and it may improve the sound environment as perceived by the staff.

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