Page 25 - Fall 2008

Table 1. Average equivalent sound pressure levels (Leq) for operating room surgeries by category (Reprinted with per- mission from reference 38. Copyright 2007, Acoustical Society of America).
uncommon. In future work, we intend to conduct studies linking specific acoustical events, such as the use of a bone saw, to measured sound pressure levels.
Noise in an adult emergency department
The constant flow of patients, doctors, nurses, and mov-
ing equipment in emergency departments all contribute to
one of the most dynamic sound environments in the hospi-
39
The Leq measured throughout the department were on average 61–69 dB(A). These levels are roughly 5–10 dB(A) higher than those measured previously at a variety of in-
2
patient units of the same hospital. The triage area at the
entrance to the department had the highest Leq at 65–73 dB(A). The measured sound pressure levels were particular- ly high in the speech frequency band. The high levels due to speech are not surprising given the large amount of verbal communication in the emergency department.
Neuro-ICU acoustics and staff response
In this study, sound measurements and staff perception evaluations were conducted in a neurological intensive care
22,23
stant monitoring by the nurses.
Average Leq values of 53–58 dB(A) were measured near
the patients. Dosimeters (body mounted microphones) worn by the staff revealed values 13 dB(A) higher than stationary microphones on average. Other acoustical metrics investigat- ed in this study were found to give a more detailed impres- sion of the sound environment than was achieved from the
overall level descriptors. Examples included statistical level distributions, restorative periods, and indoor noise criteria evaluations of spectral content. Figure 1 shows an example result from this study that presents statistical distributions of peak and maximum levels measured over five days. As shown on the figure, LMax exceeded 50 dB(A) and LPeak exceeded 70 dB(C) over 90% of the time. The behavior of noise over time was further investigated by analyzing the occurrence and length of quieter or “restorative” periods. For example, it was found that the mean length of Leq restorative periods (where Leq was below 50 dB(A) for a minimum of 5 minutes) was 9 and 13 minutes for the day and night, respectively.
Nursing staff members completed questionnaires regarding general reactions to the ICU environment as well as perceived psychological and physiological reactions. Questionnaire results indicated that 91% of those surveyed perceived noise as negatively affecting them in their daily work environment. They perceived the noise as contributing to stress symptoms such as irritation, fatigue, tension headaches, and difficulties concentrating. Some of the nurs- es in the study believed the alarm environment in particular was related to negative reactions such as influencing their ability to perform job tasks or affecting their sleep after an intensive work day. Many of the nurses were willing to con- sider alternative systems such as vibrating or visual alarms. Other studies have raised concern over the alarm environ- ment, noting the difficulties in detecting alarms due to fac- tors such as the sheer density of signals, masking effects of
Twenty-four hour noise measurements were conducted in an adult emergency department to gain a better under- standing of the soundscape in this busy space. The data were analyzed to determine the Leq, LMin, and LMax levels as well as frequency distribution in octave bands.
tal.
The data were analyzed to determine the Leq, LMin, LMax, and LPeak levels as well as fre- quency distribution in octave bands. The patients in the Neuro-ICU were sedated most of the time and required con-
unit (Neuro-ICU) over five days.
40,41
from previous work also indicate that even experienced staff
background noise, and the hearing acuity of staff.
Results
members incorrectly identify many alarms.
Aural connectivity for ICU staff
42
This on-going study examines how architectural design and material properties influence the concept of “aural con- nectivity” where staff members rely on localization of audito-
24 Acoustics Today, October 2008
Fig. 1. Statistical level distributions of peak and maximum levels measured in a neurological intensive care unit. Y-axis represents the percent of time that (a) LAFMax and (b) LCPeak exceed values shown on the x-axis (Reprinted with permis- sion from ref. 22, Copyright 2008, Acoustical Society of America).