Assessment and characterization of sound pressure levels in Portuguese neonatal intensive care units

Abstract

In NICU, systematic exposure to sound pressure levels above the recommended can affect both ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 neonates and staff. This study aimed to evaluate the sound pressure levels in three Portuguese NICU and the noise perception of staff. The measurements were performed with a sound level meter, considering the location of the main sources of noise and the layout of the units. A questionnaire was applied to assess noise perception of professionals. The staff classified the environment (regarding noise) as -slightly uncomfortable‖ (41.1%) and 48.4% considered it as -acceptable‖. In addition, the majority (55.5%) considered -equipment‖ as the most annoying source of noise. The results showed that noise levels were excessive in all the evaluated areas of the NICUs, exceeding international guidelines, with the levels ranging between 48.7 dBA to 71.7 dBA. Overall, there is a need for more research in order to verify the effectiveness of some actions and strategies to reduce the impact of noise in NICU.

Influence of the NICU on the Acoustic Isolation of a Neonatal Incubator

“…Numerous studies affirm that neonatal intensive care units (NICU) are noisy environments exceeding recommended sound levels (1)(2)(3) and that high noise levels have a significant impact on the health of preterm infants (4)(5)(6)(7)(8). The American Academy of Pediatrics uses the U.S. Environmental Protection Agency noise standards for hospitals (45 dB during the day and 35 dB at night) and recommends avoiding sound levels over 45 dB in NICU environments (9,10).…”

“…The spectral content of NICUs shows a predominance of low frequencies (3,32), with the addition of some mid-high frequency Abbreviations: D, Level difference isolation index; DnT, Standardized level difference isolation index; HVAC, Heating, ventilation, and air conditioning; L in , Noise level inside the incubator; L in_63 , L in_125 , L in_250 , L in_500 , L in_1000 , L in_2000 , L in_4000 , Noise level inside the incubator at the band frequencies of 63, 125, 250, 500, 1,000, 2,000, and 4,000 Hz, respectively; L out , Noise level outside the incubator; L out_63 , L out_125 , L out_250 , L out_500 , L out_1000 , L out_2000 , L out_4000 , Noise level outside the incubator at the band frequencies of 63, 125, 250, 500, 1,000, 2,000, and 4,000 Hz, respectively; Nabs, Room with acoustic absorbent covering; NICU, Neonatal intensive care unit; Nreverb, Room with reverberant surfaces; R ′ , Apparent sound reduction index; RIR, Impulsive response of a room; RT, Reverberation time; RT in , Reverberation time inside the incubator; RT in_63 , RT in_125 , RT in_250 , RT in_500 , RT in_1000 , RT in_2000 , RT in_4000 , Reverberation time inside the incubator at the band frequencies of 63, 125, 250, 500, 1,000, 2,000, and 4,000 Hz, respectively; RT in_Nreverb , Reverberation time inside the incubator measured in the room with reverberant surfaces; RT out , Reverberation time outside the incubator; RT out_63 , RT out_125 , RT out_250 , RT out_500 , RT out_1000 , RT out_2000 , RT out_4000 , Reverberation time outside the incubator at the band frequencies of 63, 125, 250, 500, 1,000, 2,000, and 4,000 Hz, respectively; SPL, Sound Pressure level; RT out_Nreverb , Reverberation time outside the incubator measured in the room with reverberant surfaces; T 0 , Reference reverberation time of the standardized level difference equation defined by the ISO16283-1; T, Reverberation time of the receiver room within the standardized level difference equation; T20, Time in which the sound pressure level decays 20 dB multiplied by 3; T30, Time in which the sound pressure level decays 30 dB multiplied by 2.…”

“…Most studies have used Leq, which is the energy contained in the entire spectrum, to evaluate noise in NICUs and incubators; there have been some exceptions, including the studies carried out by Santos et al, Hernández Molina et al, and Fernández Zacarías et al (3,33,36). However, this parameter does not indicate which frequencies are dominant.…”

The Effectiveness of Noise Reduction Interventions in Neonatal Intensive Care Units

“…Consequently, premature neonates hear sounds nearly similar to normal infants (Eggermont 2017). The range of hearing stimulation threshold in the 28-27 week is 40 dB and reaches 13.5 dB at 42 weeks of gestation, indicating continued evolution of the auditory nerve pathway through the term (Manske 2017;Santos et al 2018).…”

Results of an Acoustic Incubator Cover among Preterm Infants: Incubators and Modes of Respiratory Therapy

“…Ambient neonatal intensive care unit (NI-CU) noise continues to exceed American Academy of Pediatrics (AAP) guidelines [1][2][3][4][5][6][7][8] . Incubators provide some attenuation in SPL from ambient noise depending on model and proximity of operating respiratory support modes [9][10][11][12][13][14][15] .…”