Unit:
Κατεύθυνση Ακοολογία–ΝευροωτολογίαLibrary of the School of Health Sciences
Author:
Karapatsas Ioannis
Supervisors info:
Αθανάσιος Μπίμπας, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Κωνσταντίνος Παστιάδης, Καθηγητής, Τμήμα Μουσικών Σπουδών, ΑΠΘ
Ιωάννης Ξενέλης, Ομότιμος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Original Title:
Ωτοακουστικές εκπομπές προϊόντων παραμόρφωσης στα 6 kHz ως συνάρτηση του χρόνου μετά από έκθεση σε μουσική
Translated title:
Distortion products otoacoustic emission levels at 6 kHz as a function of time following music exposure
Summary:
Introduction: Current research regarding the exectiveness of otoprotective agents in the prevention of temporary or permanent threshold shift due to noise exposure is seeking objective and reliable biomarkers, able to detect subclinical impairments of cochlear function. Measurements of the distortion products otoacoustic emissions amplitude levels detect the outer hair cell impairment caused by the damaging exect of noise and they are often used as an outcome measure in experimental and clinical studies. In the present study we used a validated TTS inducing paradigm exposing volunteers to music, with the aim of measuring the amplitude changes of DPOAEs at 6 kHz in relation to time.
Method: Adult volunteers with normal findings at the otologic examination and normal pure tone audiometry and tympanometry measurements were recruited. The left ear of thirteen volunteers was exposed to music stimulus by means of headphones, at 100 dBA sound pressure level for a fifteen-minute duration time. DPOAEs amplitude level measurement was performed at six predetermined time points, at 2', 4', 8', 16', 32' and 64' post-exposure. The participants were questioned about tinnitus or aural fullness symptoms at the end of the exposure procedure and about the comfort level they experienced during the exposure to music. Follow-up examination (pure tone audiometry and DPOAEs 6 kHz level measurement) was performed in the next 72 hours.
Results: A decrease in DPOAEs 6 kHz amplitude level was observed for most participants, mainly at the 2' and 4' post-exposure measurement. Gradual recovery of DPOAE amplitude level was detected at sequential measurements, so that at 64' the amplitude level approached the reference values. One volunteer presented an increase of DPOAE amplitude level at 2', followed by a significant decrease at the 4' measurement. In four volunteers we did not record any significant amplitude shift post-exposure. The procedure was well tolerated by the participants, whereas four persons experienced short-term tinnitus. In three volunteers we observed a TTS at the time of follow-up pure tone audiometry.
Discussion: The present study is the first one to record the rate of DPOAEs 6 kHz amplitude level shift in relation to time, following exposure to music stimulus with level and duration features potent enough to cause temporary threshold shift in healthy adults with normal hearing. The observed significant decrease of amplitude level recorded at the first four- minute measurements was succeeded by a gradual recovery of amplitude to the levels of reference values at the 64’ time point. Some volunteers did not present any significant DP amplitude shift, probably due to dixerences regarding personal susceptibility to noise overexposure.
Conclusion: This study records the time-related DPOAEs 6 kHz amplitude level shift that represents the functional impairment of outer hair cells due to noise exposure, confirming the role of DPOAEs as a reliable and sensitive biomarker of current research in the field of noise- induced hearing loss.
Main subject category:
Health Sciences
Keywords:
Distortion product otoacoustic emissions at 6 kHz, Time, Biomarkers, Music-induced hearing loss, Temporary threshold shift
