ACOUSTICS
absorbing barriers in the room and/or around the beds in order to reduce the amount of sound reaching the patients’ head position. These would need to be designed in order not to affect the patients’ comfort, communication, and general wellbeing.
Electronics students looked into an option of using active noise control (ANC) to combat sounds of certain frequencies present in the ICU environment.2,3
ANC
relies on the use of adaptive filtering techniques similar to ones used in high- end headphone technology, in order to cancel undesired signals with an ‘anti- noise’ signal. These two signals would destructively interfere, creating the desired zone of silence (Fig. 1) at a desired position, in this case at the patient’s bed and head position in particular.
Accurate measurement of sound pressure levels The project also looked at designing a reliable and accurate method to measure the sound pressure levels (SPLs) at a number of locations in the room (i.e. ICU) over a long period of time, and safely log those measurements for further retrieval and analysis. An option to record not just the SPLs, but also the actual sounds causing the highest noise levels, has been considered, but not implemented, in this relatively short study. Although this would give a better insight into types and causes of noise in the ICU, due to privacy issues, a method to detect and remove any conversation (i.e. human speech) from the recordings would have to be developed and implemented before this approach could be used. The project’s short duration did not allow this option to be properly investigated.
The project was proposed by Dr Branislav Vuksanovic, Senior lecturer at the School of Energy and Electronic Engineering at the University of Portsmouth. As part of the project we visited Queen Alexandra Hospital in Portsmouth, and collaborated with the Acoustics and Vibration Research Group at the University of Valladolid in Spain. The project is, in fact, an ongoing, rather than a completed one, the overall goal being to develop, and, if possible, implement and test, several ideas that will then be further considered and pursued in future years during further ‘Group Project’ modules at the University of Portsmouth.
Completed work Public Survey
A questionnaire consisting of 14 questions was put to the general public and healthcare staff to gain some initial data and current opinions on noise
Stress
Frustration/annoyed Lack of sleep Anxiety
Lack of peace
Struggle with communication Confusing
Poor mood/Feeling bad Can’t relax/rest Causing discomfort Worried/scared Recovery time Other
0 3 4 25 7 3 11 14 5 10 15 20 Percentage
Figure 2: Pubic perceptions of how noise affects hospital patients, based on the survey findings.
‘‘ The ANSYS
Workbench software is an engineering ‘problem-solving’ software that allows various scenarios to be simulated within a variety of disciplines
levels within hospital settings. The questionnaire was shared across social media, and distributed using other forms of communication. Feedback was collected from 135 respondents, 68 of whom had experienced an ICU environment, with the remaining 29 hospital personnel. The ‘quality of the recovery environment within a hospital is clearly considered key to effective recuperation. Indicative results on the effects of noise on patients in a hospital setting are shown in Figure 2.
A similar study completed in 2011 found that the principal impact of excessive
noise on patients was lack of sleep. This is reflected in Figure 2, with 32% of the responses highlighting the same impact. Among the other major impacts on patients that are particularly worth noting are: n ‘Can’t relax/rest’. n ‘Become stressed’. n Recovery time is affected.
The upshot of the findings is that excess noise needs to be combated if patients are to recover successfully.
Acoustic modelling
Acoustic modelling enables the sound field and pressure levels to be predicted, which is important when considering different materials and designs for rooms. I-Simpa software, developed by scientists in France, is a sound propagation modelling software system that has the ability to be applied to complex geometrical domains. Material properties can be set, and 3D CAD models imported into the software for analysis. The frequencies of sound sources can also be set. Various calculations can be carried out to achieve noise maps, reverberation times, lateral sound levels, ‘and more’. Figure 3 shows an I- Simpa simulation.
Figure 3: An I-Simpa simulation. 26 Health Estate Journal October 2019
The ANSYS Workbench software, meanwhile, is an engineering ‘problem-solving’ software that allows various scenarios to be simulated within a variety of disciplines, including vibration, fluid dynamics, and heat transfer. It is the popular choice in industry to validate ideas before being sent for production, as ANSYS puts it, ‘saving time, energy, and resources’.
25 30 35 4 5
8 8
15 32
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160
