What is sound?

According to Oxford Languages, sound is defined as “vibrations that travel through the air or another medium and can be heard when they reach a person’s or animal’s ear.” If that’s the case, can we say that physical vibrations, like ultrasounds or infrasounds, which humans or certain animals cannot hear, are not sounds? Or what about tinnitus or auditory hallucinations, where no physical vibrations exist but are perceived by the brain—can these be considered sound?

The human audible range is typically described as 20 to 20,000 Hz, but this can vary with age and hearing loss. A sound at around 18,000 Hz, for instance, might be audible to some individuals but not others. In this case, is it still sound?

In essence, sound can be understood as something relative, based on each individual’s perception. Even if a sound is not perceived by everyone, if I can hear it, I could still call it sound. Conversely, if a sound is universally audible but I cannot hear it, then I cannot recognize it as sound. This makes sound a subjective experience.

This relativity of sound also manifests in situations where sounds are commonly heard by many. Take, for instance, a Christmas carol playing at Christmas evening. A person spending a happy time with their loved one may find the music joyful and romantic, while someone who has lost someone dear around Christmas might hear the same carol as somber or even sorrowful. Physically, the sound remains the same, yet the perception of it differs depending on the listener’s emotions and experiences. It might be worth considering whether this idea should be explored further under the concept of sound’s relativity.

Among people with hearing impairments, there are those whose condition is caused by damage to the eardrum or auditory organs, either congenitally or acquired, and those whose impairment is due to damage in the brain regions that process electrical signals from the auditory organs. While the latter type of hearing loss is currently difficult to rehabilitate, the former can sometimes be partially restored using various assistive devices. One such device is the cochlear implant, which sends electrical signals directly to the auditory nerve, enabling sound perception for people with hearing loss. However, the sound they perceive is quite different from what people with typical hearing experience. It often sounds mechanical or muffled, like hearing underwater.

This serves as a compelling example of the relativity of sound. In fact, Wonwoo Lee from South Korea has utilized this concept to create music specifically designed for cochlear implant users, allowing them to share a musical experience with those who have normal hearing.

The relativity of sound is not only an intriguing topic for reconsidering the very definition of sound itself but also a concept that can be harnessed to create new forms of art with entirely different purposes. Exploring this idea could be fascinating because it opens up possibilities for producing art that is based on individual perceptions and experiences of sound. By acknowledging the subjective nature of how sound is received and processed, we can craft artistic expressions that resonate differently with each listener, ultimately creating unique, personalized experiences.