Many audiologists are aware that the human hearing range typically spans from 20 Hz to 20 kHz, which may slightly decrease as we age, possibly down to 12-15 kHz. However, it’s always more intriguing to surprise your colleagues with lesser-known facts.
So, for your next audiological trivia challenge, consider asking, “Which species can hear up to 300 kHz?”
This question is sure to amaze your audience or colleagues, as hearing frequencies this high are almost unbelievable. While our favorite audiology trivia game might not make a comeback at the annual American Academy of Audiology Convention, these unique audiology facts could help you win other trivia contests!
Dolphins, for instance, possess hearing sensitivity about ten times greater than humans and can detect sounds in an incredibly high frequency range, roughly around 160 kHz. This high-frequency hearing is crucial for their communication and echolocation abilities. Interestingly, dolphins have very small ears located behind their eyes, which is often overlooked by many.
Another remarkable fact is that bats were long believed to have the highest frequency hearing, reaching up to 217 kHz, which they use for echolocation. By emitting high-frequency calls and analyzing the returning echoes, both bats and dolphins essentially “see” their surroundings in detail.
Traditionally, scientists thought that bats determined the size of nearby objects based on the strength of these echoes. However, a recent study challenges this notion. According to Castro (2011), what truly matters to bats is an echo parameter known as “sonar aperture,” which refers to the spread of angles from which echoes reach the bats’ ears. A larger spread indicates a larger object.
If you want to outshine your competition in the trivia contest, you can impress with your knowledge of bat hearing, their use of echolocation, and the limitations of their hearing. But you’ll be a tough contender to beat if you also mention that the Greater Wax Moth can hear up to a remarkable 300 kHz. While the echolocation abilities of bats are fascinating, the Greater Wax Moth’s hearing capabilities surpass them all.
Greater Wax Moth. Image credit: Univ. Florida
Incredible Hearing of Moths
Research conducted in Glasgow, Scotland, UK strongly supports the idea that these moths possess an astonishingly high-frequency hearing ability. Dr. James Windmill, from the University of Strathclyde’s Centre for Ultrasonic Engineering, has uncovered the remarkable sensory capabilities of these moths, offering new possibilities in the field of air-coupled ultrasound. According to Windmill, “We were genuinely surprised to discover that these moths can detect sound frequencies at this level. We aim to leverage this discovery to enhance our understanding of air-coupled ultrasound.”
He goes on to explain:
“While it’s not entirely clear how these moths have evolved to hear such high frequencies, it’s possible that they’ve developed this skill to improve communication and avoid predation by their natural enemy, bats, which use similar sounds.”
Before Dr. Windmill’s team’s research, previous attempts to test the hearing of the greater wax moth had been abandoned as they couldn’t detect frequencies beyond 100 kHz. Dr. Windmill’s team used a vibrometer to measure how the moths’ ears responded to sound waves, in addition to monitoring electrical signals in the auditory nerve.
They observed that as the sound frequency increased, the auditory response eventually disappeared at 300 kHz.
Do we Really Care?
While the Greater Wax Moth’s ability to hear up to 300 kHz may seem interesting, it holds significant importance. Ultrasound communication in the air is notably challenging as high-frequency signals quickly lose strength in this medium.
Notably, animals like bats use ultrasound for communication, and now, it’s evident that the Greater Wax Moth has a more advanced use of sound than bats. These research findings provide a valuable foundation for Dr. Windmill and his team to advance their knowledge of ultrasound, particularly in terms of transmitting and receiving ultrasonic pulses in the air.
With unparalleled frequency sensitivity in the animal kingdom, this moth is well-equipped to adapt to any changes in bat echolocation calls, in what appears to be an ongoing evolutionary struggle between bats and moths.
Dr. Windmill’s diverse research team is currently applying their biological insights into insect ears to create micro-scale acoustic systems. By exploring the extraordinary capabilities of the moth’s ear, they hope to develop new technological innovations, such as miniature microphones.
References:
- Castro, J. (2011). New picture of bats acoustic sense emerges. Live Science. Retrieved January 17, 2017.
- Moir, H., Jackson, J., & Windmill, J. (2011). Extremely high frequency sensitivity in a ‘simple’ ear. Biology Letters, 2013; 9 (4). Retrieved January 17, 2017.
About the author
Robert M. Traynor, Ed.D., is a hearing industry consultant, trainer, professor, conference speaker, practice manager and author. He has decades of experience teaching courses and training clinicians within the field of audiology with specific emphasis in hearing and tinnitus rehabilitation. He serves as Adjunct Faculty in Audiology at the University of Florida, University of Northern Colorado, University of Colorado and The University of Arkansas for Medical Sciences.
**this piece has been updated for clarity. It originally published on January 19, 2017
