Vision is right up there when it comes to senses but believe me; Sound is also on the top!
In fact Sound is the drive behind an almost blind bat, the SONAR and even the USG machine!
It is all in the sound!
Then again too much sound is also not good! Which is why you have this reflex which is done by the smallest muscle attached to the smallest bone in the body which protects you even when you are asleep or unconscious (to an extent!)!
To think that all this is routine for the flying fox!
The reflex is called the Acoustic Reflex.
The acoustic reflex, also known as the stapedial reflex, is crucial for protecting the inner ear from damage caused by loud noises and for enhancing speech perception in noisy environments. It involves the contraction of the stapedius muscle, which reduces the intensity of sound reaching the cochlea. This reflex also plays a role in speech discrimination, particularly in the presence of background noise. In humans there are in fact two muscles which get contacted namely the stapedius and the tensor tympani!
Of course the primary function of the acoustic reflex is to protect the inner ear (cochlea) from potential damage caused by loud sounds. When a loud sound enters the ear, the stapedius muscle contracts, stiffening the ossicular chain (bones in the middle ear) and reducing the sound’s transmission to the cochlea.
This protective mechanism helps prevent damage to the delicate hair cells within the cochlea, which are responsible for transducing sound vibrations into electrical signals for the brain. This acoustic reflex can also improve speech understanding in noisy environments. By reducing the intensity of background noise, the reflex can make it easier to hear and understand speech, especially low-frequency sounds.
This is the reason why the acoustic reflex test is a standard part of audiological assessments. By the way this reflex is the most social! Even if one ear is stimulated, if everything is working well; both ears are contracted equally!
This is of course more important in Bats!
In echolocating bats, the acoustic reflex acts as a protective mechanism, attenuating the intensity of incoming sounds, especially those produced by the bat itself, allowing them to hear faint echoes without being overwhelmed by their own vocalizations.
Bats use echolocation to navigate and find prey by emitting high-frequency calls and analyzing the returning echoes. These calls are relatively loud, and the acoustic reflex helps prevent the bat’s own vocalizations from damaging its hearing!
By reducing the intensity of self-produced sounds, the acoustic reflex allows bats to maintain their high sensitivity to faint echoes, which are crucial for accurate echolocation. The acoustic reflex is a relatively fast mechanism, with a latency of a few milliseconds, ensuring that the attenuation occurs quickly enough to protect the bat’s hearing during the brief interval between vocalization and the return of echoes. Of course even this tiny gap can cause trouble in the long run!
So while the acoustic reflex provides significant protection, it may not always be completely sufficient, and bats may still experience some level of hearing loss, particularly with age or due to prolonged exposure to loud sounds.
Old age though should not limit anyone! Fauja Singh was one such exceptional personality who became a legend after the age of 80! How he ran!
Such a great tragedy
Heartfelt condolences
Om shanti…
ramadocblog 