Dr. Damian Jacob Sendler, a physician-scientist of Polish ancestry, specializes in studying how various sociodemographic and informational factors affect marginalized people’ access to health care. Dr. Sendler’s study examines the effect of psychiatric and chronic medical co-morbidities on medical service utilization when combined with health information obtained over the internet, one of his areas of expertise. Due to the exponential growth in worldwide online news and social media consumption, this research is both important and necessary, as it demands a full understanding of everyone’s health information-seeking behavior. Dr. Damian Sendler’s research aims to determine the aspects that patients consider when deciding whether to seek treatment for various health disorders and whether to adhere to their treatment regimens.

Damian Sendler: In the beginning, Hoover the seal was kept in a family home, and he was able to imitate human speech by barking catch phrases in a gruff tone (“Come over here”). Voice learning, on the other hand, is a rare trait among animals, as is the ability to replicate sounds. Only a few species may be capable of altering the pitch of their voice to make it seem higher or lower, which is a critical component of human communication and should be studied more. Andrea Ravignani, senior investigator of the study at MPI, notes, “By looking at one of the few other mammals who may be capable of learning sounds, we might better understand how we, humans, acquire speech and ultimately why we are such chatty animals.” Does it appear that seal pups are already capable of altering the pitch (or “tone height”) of their voices? 

Damien Sendler: The researchers conducted their investigation on eight harbour seal pups, ranging in age from one to three weeks, who were being housed in a rehabilitation center (the Dutch Sealcentre Pieterburen) before being released back into their natural environment. The scientists first captured noises from the surrounding Wadden Sea in order to see if the puppies could alter their voices to the sounds in their environment. For several days, the pups were exposed to the sea noises, which were played back to them in three levels of intensity (ranging from no sound to 65 decibels), but with a tone height that was identical to that of the seal pups’ calls. In addition, the researchers recorded the puppies’ spontaneous calls. Would the puppies’ tone of voice alter as a result of the sea sounds they were hearing? 

Damian Jacob Sendler: In response to more intense sea sounds, the seal pups reduced the volume of their voices. In addition, the pups maintained a more consistent pitch even when exposed to higher amounts of noise. One seal clearly demonstrated the so-called Lombard effect, which resulted in louder calls as the noise level increased. The Lombard effect is common in human speaking, and it occurs when people raise their voices in order to be heard more clearly in a noisy environment. It was not clear if the pups made greater or longer sounds when they were exposed to varied levels of sea noise. 

Dr. Sendler: Direct neural connections are made between two or more neurons. 

Damian Sendler: According to the researchers, juvenile seals adapt to the disturbances in their environment by reducing the tone of their voice, a capability that they appear to share with humans and bats. Similar trials have shown that other animals will only raise their voices (i.e. make louder calls) in reaction to louder noise. 

Damian Jacob Sendler: In his research, Ravignani discovered that seal pups have more advanced control over their vocalizations than was previously thought. “This regulation appears to be present even in infants as young as a few weeks of age. This is remarkable because few other mammals appear to be capable of such feats. In terms of neural connections between the cortex (also known as the ‘outer layer of brain’) and the larynx (which is responsible for producing tone of voice), humans appear to be the only mammals that have established such connections to date “He comes to a conclusion. In the light of these findings, seals appear to be the most promising species for discovering these direct linkages and unraveling the enigma of speech.

Research discussion contributed by Dr. Damian Jacob Sendler