Do short-tailed fruit bats suffer hearing damage after noise exposure?

Keegan Eveland1 – kevelan1@jhu.edu
Bluesky: keeganeveland
Instagram: @keveland3

Capshaw G.1,2*
Lauer, A. 2,3,4
Moss, C.F.1,3,5,6

  1. Department of Psychological and Brain Sciences
    Johns Hopkins University
    Baltimore, MD, 21218
  2. Department of Otolaryngology-Head and Neck Surgery
    Johns Hopkins University School of Medicine
    Baltimore, MD, 21205
  3. The Solomon H. Snyder Department of Neuroscience
    Johns Hopkins University School of Medicine
    Baltimore, MD, 21205
  4. Center for Functional Anatomy and Evolution
    Johns Hopkins University School of Medicine
    Baltimore, MD, 21205
  5. Department of Mechanical Engineering
    Whiting School of Engineering
    Johns Hopkins University
    Baltimore, MD, 21218
  6. Kavli Neuroscience Discovery Institute
    Johns Hopkins University
    Baltimore, MD, 21218

*Co-first author

Popular version of 2aAB8 – Noise-induced hearing loss susceptibility in the short-tailed fruit bat (Carollia perspicillata)
Presented at the 190th ASA Meeting
Read the abstract at https://eppro01.ativ.me/web/index.php?page=Session&project=ASASPRING2026&id=4082866

–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–

Hearing is crucial to many animal species that use sound to navigate, communicate, and avoid predators. Despite its importance, hearing in many animals is damaged by exposure to loud sounds. One exception is the echolocating bat, an animal that navigates in the dark using sound alone. While some vertebrates like fish and birds can regenerate the sensory cells that support hearing, mammals cannot, and hearing loss, caused by aging and exposure to loud noise, is common among mammals. This is what makes bats an intriguing case: bats can emit extremely loud ultrasonic calls (110 – 140 dB), the equivalent of a rock concert, yet some species show exceptional resistance to both age-related and noise-induced hearing loss.

However, not all bats are equally resistant to hearing loss; the ability to maintain hearing after noise exposure and into old age appears to reflect the degree of reliance on hearing for survival. For example, the big brown bat (Eptesicus fuscus), uses its hearing to hunt insects and is more resistant to both age-related and noise-induced hearing loss than the Egyptian fruit bat (Rousettus aegyptiacus), a frugivorous species that relies more heavily on vision for navigation and loses its hearing with age. This raises the question: What mechanisms make some bat species more resistant to hearing loss than others?

In this study, we examined noise susceptibility in the short-tailed fruit bat (Carollia perspicillata), which represents an interesting middle ground between these two species. Like the big brown bat, short-tailed fruit bats rely primarily on echolocation for navigation. However, like the Egyptian fruit bat, it feeds mainly on fruit and can supplement echolocation with other senses such as smell during foraging.

We hypothesize that short-tailed fruit bats maintain their hearing sensitivity even after exposure to loud noise, given their reliance on echolocation for navigation. To test this, we measured the bats’ hearing before and after one hour of exposure to intensely loud, 110 dB noise. We used two complementary methods: auditory brainstem responses, which assess auditory nerve and brainstem responses to sound, and otoacoustic emissions, which evaluate the functionality of the sensory cells that support cochlear amplification in the inner ear.

Our preliminary results show no long-term hearing damage following noise exposure, suggesting that short-tailed fruit bats possess protective mechanisms to preserve their most critical sense. These findings strengthen evidence that echolocation-dependent bats protect their hearing against noise damage better than those that primarily rely on other senses (such as vision). Understanding the biological mechanisms underlying this protection could have implications beyond bats and may reveal new strategies for preventing noise-induced hearing loss in other species.

 

Comparison of sonar reliance and hearing loss susceptibility among Egyptian fruit bats, short-tailed fruit bats, and big brown bats.

Meta-Earplugs Reduce Booming Voice Effect, Low-Frequency Rumbling Sounds

More comfortable earplugs mean increased use and lower rates of hearing loss.

Left: Artificial head with metal plate in place of the ear in a lab setting. Right: Person with long hair wearing a gray Meta-earplug in their ear, with a black speaker mounted on a stand in a testing room.

The authors tested the 3D-printed meta-earplug on an artificial head and a group of human participants, demonstrating an effective reduction in low-frequency sound. Credit: Carillo et al.

WASHINGTON, April 28, 2026 — Workplace hearing loss is one of the most common work-related illnesses. While hearing loss is preventable with earplugs, they can be uncomfortable, and users often remove them despite the risks. Low-frequency sounds, such as rumbling traffic and warehouse vibrations, are especially difficult to address because differences in ear physiology allow sound to leak into ears, despite protection from earplugs.

Traditional earplugs also make the user’s voice sound booming and hollow, known as the occlusion effect. It is caused by vocal vibrations that travel through bones and build up pressure on the eardrum when the ear canal is blocked with an earplug.

In the Journal of the Acoustical Society of America, published by AIP Publishing, researchers at…click to read more

From: The Journal of the Acoustical Society of America
Article: Voice clones are easier to understand in noise than their human originals: the voice cloning intelligibility benefit
DOI: 10.1121/10.0043161

More Press Releases

Hearing Loss in Old Age Isn’t Due to Normal Aging

Daniel Fink MD – DJFink@thequietcoalition.org

Program Chair
The Quiet Coalition
A program of Quiet Communities, Inc.
P.O. Box 533
Lincoln MA, USA

Popular version of 4aPP11 – Moderate to severe hearing loss is not part of normal aging
Presented at the 189th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0041135

–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–

Is hearing loss in older people normal? It certainly is common, but the radical conclusion proposed in this summary paper is that it isn’t part of normal aging. Hearing loss in older people, technically called presbycusis or age-related hearing loss, is really the result of exposure to too much noise over one’s lifetime. The hearing loss common in old age is entirely preventable by reducing exposure to loud noise. Figure 1 shows how too much noise causes hearing loss by damaging the hair cells in the cochlea in the inner ear.

Figure 1. Top: Auditory structures from external ear (pinna) to auditory nerve. Bottom: Normal and damaged hair cells. From Centers for Disease Control and Prevention. How does loud noise cause hearing loss?

Why does this matter? If something is caused by normal aging, like thinning gray hair, nothing can be done about it. But if a condition common in old age is due to something that can be changed, like diet, exercise, or avoiding harmful exposures, maybe it can be delayed or prevented entirely.

Many conditions common in older people, once thought to be due to normal aging, have been shown to be preventable. These include obesity, diabetes, high blood pressure, muscle weakness, heart disease, skin cancers, and even dementia. Age-related hearing loss should be added to this list.

A number of studies done in the 1960s in isolated populations not exposed to loud noise found good hearing preserved to age 70. For example, a study of hearing in the isolated Mabaan population in the Sudan published in 1962 found good hearing preserved to age 70. Figure 2 shows that anything more than a 10-decibel hearing loss may not be normal.

Figure 2. Hearing loss in women and men in industrial societies and the non-industrialized Mabaans. Adapted by Kathleen Romito MD from Figure 11 in Kryter KD. Presbycusis, sociocusis and nosocusis. J. Acoust. Soc. Am. 1 June 1983; 73 (6): 1897–1917. https://doi.org/10.1121/1.389580.

Other lines of evidence supporting the conclusion that hearing loss in old people isn’t due to normal aging include:

  • Occupational studies showing exactly how much noise causes hearing loss. This is the basis of noise exposure limits for workers. Everyone’s ears are the same. If noise causes hearing loss in workers, it has to cause hearing loss in everyone.
  • Boys and girls have equal hearing at birth, but by the teen years and into adulthood, women have better hearing than men. [See Figure 2.] Girls and women generally don’t do noisy things like hunting or woodworking, or work in noisy factories or mines or operate heavy equipment.
  • Workplace hearing loss occurs in the frequencies the ear is exposed to. For example, dentists have high-frequency hearing loss in the ear nearest the drill.
  • How noise damages hearing is well-understood, down to the cellular, subcellular, and molecular levels.

What else could cause age-related hearing loss? Some experts mention drugs that damage the ear, hardening of the arteries, genes that cause hearing loss, or nutritional factors, but seem to ignore or downplay noise. The published evidence, though, doesn’t support a major role for any of these other factors.

Recent research supports the conclusion that hearing loss in older people can be prevented. The upper left-hand graph in Figure 3 shows that normal hearing loss in older people is minimal, about 10 decibels at 4,000 Hertz (cycles per second ) as in Figure 2.

Figure 3. Mean audiograms and standard errors of exemplars (filled symbols) and non-exemplars (open symbols) in four audiometric phenotypes. Reproduced with permission from Dubno JR, Eckert MA, Lee FS, et al. Classifying human audiometric phenotypes of age-related hearing loss from animal models. J Assoc Res Otolaryngol. 2013 Oct;14(5):687-701. https://pmc.ncbi.nlm.nih.gov/articles/PMC3767874/

Why does prevention of age-related hearing loss matter? Hearing aids are expensive. Only one-third of older Americans who might benefit from hearing aids have them. Even in countries where hearing aids are provided by the national health insurance program, many people don’t want them. There is a stigma attached to hearing loss and to wearing hearing aids. Also, hearing aids don’t restore normal hearing and don’t work as well as desired in noisy restaurants or at parties,

CDC states that noise-induced hearing loss is the only type of hearing loss that is 100% preventable. Preventing age-related hearing loss is simple and inexpensive: reduce lifetime noise exposure. If something sounds loud, it’s too loud, and one’s auditory health is at risk. Turn down the volume, insert earplugs, or leave the noisy environment and you won’t need hearing aids when you get old.

More information can be obtained from the poster at https://virtual.posterpresentations.com/research/presentation/ID279825/.

Teaching about the Dangers of Loud Music with InteracSon’s Hearing Loss Simulation Platform

Jérémie Voix – Jeremie.Voix@etsmtl.ca

École de technologie supérieure, Université du Québec, Montréal, Québec, H3C 1K3, Canada

Rachel Bouserhal, Valentin Pintat & Alexis Pinsonnault-Skvarenina
École de technologie supérieure, Université du Québec

Popular version of 1pNSb12 – Immersive Auditory Awareness: A Smart Earphones Platform for Education on Noise-Induced Hearing Risks
Presented at the 186th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0026825

–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–

Ever thought about how your hearing might change in the future based on how much and how loudly you listen to music through earphones? And how would knowing this affect your music listening habits? We developed a tool called InteracSon, which is a digital earpiece you can wear to help you better understand the risks of losing your hearing from listening to loud music trough earphones.

In this interactive platform, you can first select your favourite song, and play it through a pair of earphones at your preferred listening volume. After providing InteracSon with the amount of time you usually spend listening to music, it calculates the “Age of Your Ears”. This tells you how much your ears have aged due to your music listening habits. So even if you’re, say, 25 years old, your ears might be like they’re 45 years old because of all that loud music!

Picture of the “InteracSon” platform during calibration on an acoustic manikin. Photo by V. Pintat, ÉTS/ CC BY

To really demonstrate what this means, InteracSon provides you with an immersive experience of what it’s like to have hearing loss. It has a mode where you can still hear what’s going on around you, but it filters sounds based on what your ears might be like with hearing loss. You can also hear what tinnitus, a ringing in the ears, sounds like, which is a common problem for people who listen to music too loudly. You can even listen to your favorite song again, but this time it would be altered to simulate your predicted hearing loss.

With more than 60% of adolescents listening to their music at unsafe levels, and nearly 50% of them reporting hearing-related problems, InteracSon is a powerful tool to teach them about the adverse effects of noise exposure on hearing and to promote awareness about how to prevent hearing loss.

Read the POMA: The InteracSon Immersive Auditory Platform: An initiative for promoting awareness of noise-induced hearing risks

World Hearing Day 2024

The Acoustical Society of America (ASA) takes pride in its mission to generate, disseminate, and promote the knowledge and practical applications of acoustics. This also aligns with one of the objectives of World Hearing Day 2024; to reshape public perceptions surrounding ear and hearing based on accurate, evidence-based information. In support of World Hearing Day[i], we would like to draw attention to a couple Special Issues of the Journal of the Acoustical Society of America (JASA) that delve into the clinical and investigational facets of noise-induced hearing disorders.

Noise-Induced Hearing Disorders: Clinical and Investigational Tools
Guest Editors: Colleen G. Le Prell (Liaison Guest Editor), Odile H. Clavier, and Jianxin Bao

This special issue provides valuable insights into cutting-edge clinical and investigational tools designed to sensitively detect noise injury in the cochlea. Emphasizing the importance of sound exposure monitoring and protection, the collection explores tools available for characterizing individual noise hazards and attenuation. Throughout, there is a concentrated focus on the suitability of diverse functional measures for hearing and balance-related clinical trials, including considerations for boothless auditory test technology in decentralized clinical trials. Furthermore, the issue offers guidance on designing clinical trials to prevent noise-induced hearing deficits such as hearing loss and tinnitus.

World Hearing Day JASA special issue

Issue Highlights

Noise-Induced Hearing Loss: Translating Risk from Animal Models to Real-World Environments
Guest Editors: Colleen G. Le Prell, CAPT William J. Murphy, Tanisha L. Hammill, and J. R. Stefanson

Noise-induced hearing loss (NIHL) stands as a common injury for service members and civilian workers exposed to noise. This special issue focuses on translating knowledge from animal models to real-world environments. Contributors delve into the cellular and molecular events in the inner ear post-noise exposure, exploring potential pharmaceutical prevention of NIHL. The collection includes insights into methods and models used during preclinical assessments of investigational new drug agents, as well as information about human populations at risk for NIHL.

World Hearing Day JASA Special Issue

Issue Highlights

Together, these special issues provide an exploration of noise-induced hearing disorders, offering valuable insights and potential solutions for both clinical and real-world settings. Be sure the share this post to make ear and hearing care a reality for all! For more information about World Hearing Day 2024, visit https://www.who.int/campaigns/world-hearing-day/2024.

[i] Due to an unexpected site wide issue, the posting of this content was unfortunately delayed to after March 3, 2024.