title: The effects of different noise types on heart rate variability in men.
abstract: OBJECTIVE
  To determine the impact of noise on heart rate variability (HRV) in men, with a focus on the noise type rather than on noise intensity.
  
  
  METHODS
  Forty college-going male volunteers were enrolled in this study and were randomly divided into four groups according to the type of noise they were exposed to: background, traffic, speech, or mixed (traffic and speech) noise. All groups except the background group (35 dB) were exposed to 45 dB sound pressure levels. We collected data on age, smoking status, alcohol consumption, and disease status from responses to self-reported questionnaires and medical examinations. We also measured HRV parameters and blood pressure levels before and after exposure to noise. The HRV parameters were evaluated while patients remained seated for 5 minutes, and frequency and time domain analyses were then performed.
  
  
  RESULTS
  After noise exposure, only the speech noise group showed a reduced low frequency (LF) value, reflecting the activity of both the sympathetic and parasympathetic nervous systems. The low-to-high frequency (LF/HF) ratio, which reflected the activity of the autonomic nervous system (ANS), became more stable, decreasing from 5.21 to 1.37; however, this change was not statistically significant.
  
  
  CONCLUSIONS
  These results indicate that 45 dB(A) of noise, 10 dB(A) higher than background noise, affects the ANS. Additionally, the impact on HRV activity might differ according to the noise quality. Further studies will be required to ascertain the role of noise type.
authors.affiliation: Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.
authors.forename: Chang Sun
authors.initials: CS
authors.lastname: Sim
authors.affiliation: Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.
authors.forename: Joo Hyun
authors.initials: JH
authors.lastname: Sung
authors.affiliation: Department of Urology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.
authors.forename: Sang Hyeon
authors.initials: SH
authors.lastname: Cheon
authors.affiliation: Department of Mechanical Engineering, University of Ulsan College of Engineering, Ulsan, Korea.
authors.forename: Jang Myung
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Indoor Environment & Noise Research Division, National Institute of Environmental Research, Incheon, Korea.
authors.forename: Jae Won
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Department of Occupational and Environmental Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea. oemdoc@naver.com.
authors.forename: Jiho
authors.initials: J
authors.lastname: Lee
mesh_terms: D000223:Adaptation, Psychological; D015986:Confounding Factors, Epidemiologic; D004777:Environment; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D009622:Noise; D013315:Stress, Psychological / Q000503:physiopathology; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Autonomic nervous system; heart rate variability; noise