Hearing loss is a one of the most common chronic conditions. Although it is most common to be diagnosed with hearing loss later in life due to aging, there are multiple causes of hearing loss across the lifespan. One of the main types of hearing loss is noise-induced hearing loss. Some individuals may complain of decreased hearing or word understanding in background noise but when tested, they appear to have normal hearing sensitivity in the standard audiometric frequencies (250 – 8000 Hz). This may be due to decreased hearing sensitivity in extended high frequencies, above 8000 Hz. There is growing evidence that decreased extended high frequency thresholds may be a precursor to noise-induced hearing loss. This study aimed to analyze how noise exposure affects young adult’s extended high frequency thresholds and word identification in noise as well as traditional audiological testing (pure tones, speech recognition, word discrimination in quiet, etc). Young adults (18-25 years old) were recruited through ETSU affiliated social media, ETSU faculty, and word of mouth. An online noise survey was conducted to calculate each participant’s noise exposure. An otoscopic examination was completed on each study participant. Tympanometry was performed to ensure normal middle ear immittance. If an individual did not have normal middle ear immittance they were dismissed from the study. A 12-frequency diagnostic Distortion Product Otoacoustic Emissions (DPOAEs) was performed to check integrity of the individual’s outer hair cells. Speech Recognition testing was completed to determine the lowest level the individual could repeat back 50% of the words correctly. Word Recognition testing was completed to determine the percentage of words the individual could hear and correctly identify at suprathreshold level. Words-in-Noise testing was completed to determine how an individual could hear and correctly identify speech when in the presence of noise. Puretone air conduction was completed at the standard audiometric frequencies: 250, 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz. If an individual had abnormal hearing sensitivity in these frequencies, they were dismissed from the study. Finally, extended high frequency testing was completed at 10,000, 12,500, 14,000, and 16,000 Hz. Data collection is still in progress and will close on March 7th, 2022. It is expected that noise exposure will be negatively correlated to extended high frequency thresholds and word understanding in noise (i.e., participants with more noise exposure will have poorer extended high frequency thresholds and poorer word understanding in noise).

The relationship between hearing sensitivity in the extended high-frequency region (8-16 kHz) and (1) the presence of synchronized spontaneous otoacoustic emissions (SSOAEs) and (2) the strength of click-evoked and distortion product otoacoustic emissions (CEOAEs and DPOAEs) was investigated in 104 ears of 57 young adults. The age range was confined to 16 to 19 years. All subjects had normal hearing in the conventional audiometric frequency range (0.5-8 kHz). Ears with detected SSOAEs had better hearing sensitivity in the extended high-frequency region and also higher levels of CEOAEs and DPOAEs than ears with undetected SSOAEs. The results support the hypothesis that the presence of SSOAEs is indicative of an ear with highly normal cochlear function over a broad frequency range.