Research Projects

Temporary Hearing Changes Following Recreational VR Music Concert

Temporary threshold shift refers to reduced hearing sensitivity following noise exposure, which then recovers fully within 24 hours. Noise-induced cochlear synaptopathy refers to lasting permanent damage to the synaptic connections between the inner hair cells and auditory nerve dendrites following a severe, temporary threshold shift. It has become clear that not every noise exposure that induces temporary threshold shift will result in cochlear synaptopathy. Less is known about the effects of slight (0-10 dB HL), rather than severe, temporary threshold shifts in humans, be it changes in cochlear nerve response or hearing-in-noise performance. This study analyzed slight, temporary hearing sensitivity changes after viewing a music exposure that is quantifiably a low noise risk: a 90 min live music concert using a commercially available virtual-reality (VR) headset. Notably, music in the VR concert is significantly lower (LAeq: 78.7 dB; Time Weighted Average: 72.7 dB; accounts for 6% of the daily noise limit recommended by NIOSH) than a real-world concert, yet has the potential to contribute to an accessible, standardized study design of temporary hearing changes.

Funding: NIH LRP Clinical Research Award (L30DC019804; PI Grinn)

Improving Automated Hearing Aid Safety and Audibility

The size and shape of the external-ear structures (e.g. pinna, concha, ear canal) amplify and attenuate certain frequencies, which affects the way individuals naturally hear sound – each with a slightly different spectral profile. Unfortunately, the majority of audiologists automatically program hearing aids using an average amount of external-ear amplification (up to 20 dB of error) rather than directly measuring the patient’s unique external ear amplification, which results in under-amplification (poor audibility) or over-amplification (noise-induced hearing loss). In this ongoing project, we test the hypothesis that average estimates of external-ear amplification will improve if they are normed using body height, pinna size, ear canal size, and head circumference, instead of body age.

Funding: NIH R01 (1R01DC020699-01A1; PI Grinn)

Effects of Stress on Hearing-in-Noise Performance

It is known that a higher degree of stress can negatively influence systems of the body. In the case of hearing (and listening), secure vascularization and oxygen delivery to the cochlea is critical to maintaining high metabolic activity and ionic and electrical balance of endolymph. In this study, the Perceived Stress Scale (PSS) questionnaire is administered to human research participants to analyze the effects of stress on a range of listening performance tasks.

Relationship Between Noise Exposure History and Words-in-Noise (WIN) Performance

“Hidden hearing loss” is most broadly used to describe any auditory deficit or complaint that is not overtly evidenced in the standard audiogram. The purpose of this study is to analyze the relationship between participants’ Words in Noise (WIN) scores and their noise exposure history, assessed using the Noise Risk Calculator survey, developed by the National Acoustics Laboratory. If WIN scores are related to high noise exposure, this suprathreshold measurement could potentially serve as a proxy measurement for cochlear synaptopathy in humans with clinically normal audiometric thresholds.

Funding: NIH LRP Clinical Research L30DC019804 (Grinn)

Hearing-in-Noise Deficits and Cochlear Nerve Response in “Normal-Hearing” Firearm Users

A severe degree of temporary threshold shift (>50 dB) induced by powerful noise exposure is known to cause cochlear synaptopathy (i.e. “hidden hearing loss”) in nearly all animal models. However, conclusions surrounding this effect in human models is under significant debate. This study analyzes proxy metrics of cochlear synaptopathy in youth firearm users with healthy peripheral auditory systems.

Funding: 1. American Academia of Audiology New Investigator Research Grant (Grinn); 2. National Hearing Conservation Association Research Grant (Grinn)

Funding: NIH R01 (1R01DC020699-01A1; PI Grinn)

Effects of Variable Hearing Protection Attenuation on Auditory Function in “Normal-Hearing” Firearm Users

This study tests the hypothesis that higher attenuation from ear protection devices not only preserves standard thresholds in the audiogram, but also preserves the more sensitive measures of early noise-induced hearing loss injury (i.e., measures that reflect injury before standard audiometric shifts), such as DPOAEs, Words in Noise test performance, and extended high-frequency audiometry.

Effects of Pre-Cochlear Amplification on Temporary Hearing Threshold Shift Following Virtual-Reality Music Concert

70% of individuals 18-25 years old have attended at least one live music concert. This project analyzes external-ear mechanics that may significantly contribute to making one person more susceptible to temporary hearing threshold shift than another. Participants in this study experience a popular, live music concert inside the laboratory, using a commercially available virtual reality headset.

Funding: 1. CMU Faculty Research and Creative Endeavors Grant (Grinn); 2. NIH LRP Clinical Research L30DC019804 (Grinn)

Effects of Baseline Heart Rate and Blood Pressure on Temporary Hearing Threshold Shift

Already, much attention has been paid to cardiovascular health and hearing threshold correlations – better cardiovascular health has been demonstrated to have an overarching protective value when it comes to preserved hearing. This research focuses on acute, recreational noise exposure, and the relationship between baseline heartrate, blood pressure, and hearing thresholds.

Noise-induced Threshold Shift Relative to Pre-cochlear Amplification in Chinchilla

This animal study is conducted in parallel with the human study (above) predicting individual noise-induced hearing loss risk as a function of pre-cochlear amplification, in addition to identifying proxy metrics of pre-cochlear amplification. This project gives particular relevance to improvement of clinical trial design for otoprotective drugs.

Funding: Support from NIH R01DC014088 (Lobarinas)

A Gold Standard Protocol Musician Hearing Protection Selection and Fitting

One common source of recreational noise-induced hearing loss is music-induced hearing loss (MIHL). Musicians ranging from garage band performers to professional symphony members are at risk for MIHL, as are individuals who simply appreciate music by attending loud performances such as concerts or open-mic sets. Preserving a professional musician’s hearing is not just about preserving what they love to do, but also about preserving what they’re paid to do. Standard occupational hearing protection devices do not fit the needs of musicians for a variety of reasons including poor non-custom fit inside the ears, excessive sound attenuation, and non-flat acoustic filtering. This study builds a literature review from which a gold standard clinical protocol for selecting and fitting musician hearing protection is derived.

Chronic Headphone Use In Office Settings – Occupational Risk of Music-Induced Hearing Loss in the 40 Hour Work Week

This project explores the prevalence of chronic headphone use in office settings (~8 hours a day, 5 days a week), in addition to individual knowledge and perception of auditory risk from headphones that produce high sound-levels for extended periods of time. Participants are surveyed about 1) their headphone-listening habits at work (frequency, duration, intensity), 2) their knowledge of what constitutes “hazardous” noise, and 3) explanation for their willingness (or unwillingness) to adapt safe-listening habits. Lastly, we developed several visual aids that illustrate hearing loss, and we test their motivational effectiveness in the interest of hearing conservation.

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