RESUMO
The purposes of this investigation were two-fold: (1) to determine whether differences between measured ear canal diameter and actual earplug size affect sound pressure levels in the ear canal during exposure to high levels of noise; and (2) to determine if individuals would select the insert earplugs that conform to their measured ear canal diameter if the decision were left to them. The results indicate that: (1) very small differences between measured ear canal diameter and actual earplug size affect considerably the sound pressure levels in the ear canal during exposure to high levels of noise; (2) individuals typically select earplugs that are smaller than their measured ear canal dimensions when the decision is left to them; (3) the most skilled technician cannot always determine ear canal sizes due to limitations of available measuring instruments.
Assuntos
Meato Acústico Externo/anatomia & histologia , Dispositivos de Proteção das Orelhas , Equipamentos de Proteção , Adolescente , Adulto , Tomada de Decisões , Feminino , Perda Auditiva Provocada por Ruído/prevenção & controle , Humanos , MasculinoAssuntos
Dispositivos de Proteção das Orelhas , Audição , Equipamentos de Proteção , Comunicação , Dispositivos de Proteção das Orelhas/normas , Estudos de Avaliação como Assunto , Dispositivos de Proteção da Cabeça , Perda Auditiva Provocada por Ruído/prevenção & controle , Humanos , Ruído , Equipamentos de Proteção/normas , Padrões de ReferênciaRESUMO
Audiograms were obtained on eight binaural chinchillas trained on a shuttlebox avoidance procedure. Four of the animals were exposed to three successive levels of an octave band of noise centered at 63 Hz: 100 dB SPL (74 dBA), 110 dB SPL (84 dBA), and 120 dB SPL (94 dBA). The other four animals were also exposed to three successive levels of an octave band of noise centered at 1000 Hz: 75 dB SPL (75 dBA), 85 dB SPL (85 dBA), and 95 dB SPL (95 dBA). All exposure durations were 75 h. Little threshold shift (TS) resulted from the lower two exposure levels of the 63-Hz noise band. At the 120-dB exposure level, maximum TS of 43 dB occurred at 2000 Hz. Permanent threshold shifts (PTSs) of 16 dB at 2000 Hz and 11 dB at 1400 Hz were found. Exposure to the three levels of the 1000-Hz noise band produced TSs of 20, 45, and 61 dB at 1400 Hz. The 95-dB exposure level resulted in PTSs of 6 dB at 1400 Hz and 9 dB AT 2000 Hz. The major results were (1) high-frequency hearing loss to a low-frequency noise and (2) that noise bands matched within 1 dBA were not equally hazardous as dictated by damage-risk criteria. The 63-Hz noise band produced nearly twice as much PTS as the 1000-Hz noise band.
