When two of my newborn babies spent time in the hospital due to serious medical problems, one of the many things that distressed me was all the noise surrounding them. I wanted them to be introduced to the world differently. I wanted to wrap them in the sounds of home — voices of people who loved them, clatter of dishes at dinnertime, wind in the trees, lullabies sung, books read aloud. Instead there were loud beeping devices, intrusive announcements, squeaking wheels on equipment carts. They heard all sorts of strangers’ voices too, often while those strangers (for the very best reasons) imposed discomfort or pain. When they came home, both times, I noticed the sounds around them more than I normally would just because it was such a blessed relief.
My concern wasn’t overblown. In utero, a baby hears a symphony of prenatal sound that includes the mother’s heartbeat, breathing, and movement. The baby’s auditory system is fully developed by the sixth month of pregnancy and what sounds it hears is a particularly big deal from that time until it reaches six months of age. Here’s what one medical journal has to say:
The period from 25 weeks’ gestation to 5 to 6 months of age is most critical to the development of the neurosensory part of the auditory system. This is the time when the hair cells of the cochlea, the axons of the auditory nerve, and the neurons of the temporal lobe auditory cortex are tuned to receive signals of specific frequencies and intensities. Unlike the visual system, the auditory system requires outside auditory stimulation. This needs to include speech, music, and meaningful sounds from the environment.
The preterm as well as the term infant cannot recognize or discriminate meaningful sounds with background noise levels greater than 60 dB. The more intense the background noise, especially low frequency, the fewer specific frequencies (pitch) can be heard and used to tune the hair cells of the cochlea. Continuous exposure to loud background noise in the NICU or home will interfere with auditory development and especially frequency discrimination. The initial stimulation of the auditory system (speech and music) needs to occur in utero or in the NICU to develop tonotopic columns in the auditory cortex and to have the critical tuning of the hair cells of the cochlea occur. The control of outside noise, the exposure to meaningful speech sounds and music, and the protection of sleep and sleep cycles, especially rapid eye movement sleep, are essential for healthy auditory development.
Hearing is also said to be the last sense to leave us at the end of life, as indicated by electroencephalograms of people in their last hours. (Oftentimes music can reach unconscious and dying people when other stimuli cannot.)
Sound has a way of sinking into us, linking with sensation and emotion to form lasting memories. When I read about refugees forced from their homes by war or famine or rising seas, my sorrow for them (and my admiration for their courage) leads me to think about what sensory experiences they can never fully recapture from their homelands. Keeping one’s own language, foods, and faith alive is vital but I wonder if hunger for the unique sounds left behind ever goes away.
We carry aural memories with us forever. I suspect sounds from early childhood are rooted the most deeply. Here are some of the happiest I can remember. A summer of locusts, the sound cresting and falling like waves. The screen door’s awwaak as it opened and my mother’s voice from somewhere in the house calling “don’t slam it!” The shriek of a swing hung on chains as I swung on my belly watching ants scurry below. My father whistling as he tinkered with some project. News on the radio my mother listened to for a few minutes each morning, all of it inane chatter to me except for ads that lodged in my memory like this one. Planes taking off from nearby Cleveland Hopkins Airport, curving overhead like toys even though adults insisted they were big enough to hold actual people inside (pffft!) Music my father listened to as he graded papers — classical, pop, big band. The creak of our old rocking chair. The indescribable security of lying in bed hearing my parent’s muffled voices.
Imagine sounds from 100 years ago in the place you are now. Perhaps horses on stone-paved streets, vendors hawking their wares from open carts as they traveled through town, afternoon paperboys calling out the latest headlines, church bells tolling the hours, the whistle of steam engines passing in the distance, children playing outdoors everywhere.
Or maybe imagine sounds 100 years in the future, if you can.
What sounds surrounded you as a baby? Your children in infancy? What aural memories make up who you are today?