Active Hearing Protectors and Audibility of Critical Communications

Details

• Personal Author:
  Bernstein L ; Brammer, A. J. ; Cherniack, Martin G. ; Peterson, D. R. ; Trahiotis T ; Bernstein L ; Brammer, A. J. ; Cherniack, Martin G. ; Peterson, D. R. ; Trahiotis T
• Description:
  A proof-of-concept hearing protection device (HPD) has been developed to improve the speech intelligibility of a built-in electronic communication channel while maintaining the audibility of a tonal warning sound external to the HPD, and adequate attenuation of environmental noise. The proof-of- concept device has been constructed from the mechanical components of a commercial hearing protector, and electro-acoustic and electronic components selected or developed as a result of the research conducted in this project. The device employs digital signal processing to divide the audio frequency range into separate, contiguous frequency bands that can be programmed to function independently. There are two separate and independent digital controllers. One controller is programmed to provide active noise cancelation to reduce environmental noise. The second is employed to control signals in the communication channel, which can be derived from a (remote) electronic communication source or from the environment external to the HPD. It is programmed to enhance the audibility of desired sounds, by adjusting the magnitude of the desired signal compared to that of the undesired noise. The performance of the proof-of-concept device has been established by measurements involving human subjects under conditions of environmental noise and communication that do not pose a risk to hearing, and in simulation for other conditions. A probe microphone with a miniature plastic tube that is inserted in the ear canal has been developed to record sounds at the eardrum. The microphones are used to measure the attenuation of HPDs. Psychoacoustic tests have been developed to determine thresholds for the perception of pure tones, thresholds for the perception of pure tones or warning sounds in noise, and speech understanding in noise. A surrogate objective measure of speech intelligibility has been implemented to permit the performance of the proof-of-concept device to be evaluated in simulation (Speech Transmission Index - STI). By these means, it has been shown that the sound level at the ear can be automatically reduced by frequency and level to the extent required to avoid noise-induced hearing loss, while simultaneously minimizing over-protection from noise and so maintaining situational awareness. It has also been shown, by improved word scores when subjects wear the proof-of-concept device and by increased or acceptable STI values in simulation, that the intelligibility of speech in the communication channel can be improved while maintaining adequate control of environmental noise. It has further been shown that the audibility of a tonal warning sound external to the proof-of-concept device is not degraded compared to wearing a traditional passive circumaural HPD. We thus conclude that the hypotheses, and aims, of the original proposal have been confirmed by the performance of the proof-of-concept device. [Description provided by NIOSH]
• Subjects:
  Hearing Hearing Loss Hearing Loss, Noise-Induced Noise Noise, Occupational Occupational Health Safety
• Keywords:
  Auditory Protection Communications Equipment Equipment Design Hearing Loss Prevention Hearing Protection Noise Exposure Noise Induced Hearing Loss Noise Protection
• Series:
  Grant Final Reports   ; Grant Final Reports  
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report ; Final Grant Report
• Place as Subject:
  Connecticut ; OSHA Region 1
• CIO:
  National Institute for Occupational Safety and Health (NIOSH) ; National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs ; OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health ; Workplace Safety & Health
• Location:
  North America ; North America
• Pages in Document:
  1-24
• NIOSHTIC Number:
  nn:20058829
• NTIS Accession Number:
  PB2022-100294
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R01-OH-008669, 2012 Nov; :1-24
• Contact Point Address:
  Dr. Anthony J. Brammer, University of Connecticut Health Center Ergonomic Technology Center, Department of Medicine, 263 Farmington Avenue Farmington, CT 06030
• Email:
  brammer@uchc.edu
• Federal Fiscal Year:
  2013
• NORA Priority Area:
  Construction ; Manufacturing ; Construction ; Manufacturing
• Performing Organization:
  University of Connecticut School of Medicine and Denistry, Farmington, Connecticut
• Peer Reviewed:
  False
• Start Date:
  20060801
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20120731
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:f60226a69f656f5e04622079623b1fb67da1d25d4c272fa9b68901c9027a85bfa4fafaf5ea3bed0f2de58459ee2704956c153fe8792cb7f6c7851ae657d2a615
• Download URL:
  https://stacks.cdc.gov/view/cdc/218957/cdc_218957_DS1.pdf
• File Type:
  [PDF - 734.60 KB ]