What Is the Quietest Sound a Human Can Hear?

What's the Quietest Sound a Human Can Hear
June 05, 2020

Have you ever been sitting on the couch with your dog or cat, watching a movie comfortably, when their ears perk up? What could they have possibly heard that captured their attention? They probably heard something outside that you just weren’t physically able to pick up.

Just as we humans can only see the “visible” wavelengths of light in the vast electromagnetic spectrum, we can only hear a small portion in the auditory spectrum.

So what is the quietest sound a human can hear? First, let’s take a look at how we measure sound intensity — decibels.

What Is a Decibel?

Scientists at Bell Telephone Laboratories coined the word decibel in honor of their namesake, inventor Alexander Graham Bell. As a unit of measurement, though, decibels mean nothing on their own. They’re a ratio used as a reference point. For example, it’s some current quantity we wish to define, or “x,” as it relates to our predefined “R” quantity. So then, we must know what R is. But, in this case, it’s the smallest sound the average adult can detect at 1 kilohertz, which can change from person to person.

Typically, zero decibels sound pressure level (SPL) corresponds to 0.000002 Pascals — a measure of vibration or pressure waves that we really hear. So then, zero decibels is the smallest level of sound our ears can detect!

So there’s our answer, in its simplest form. Right?

Wrong. Well, Sort Of

The quietest sound a person can hear is not always 0 dSPL. This absolute threshold of the human hearing range is an average — some people may hear much quieter sounds, while others may be harder of hearing.

Plus, this 0 threshold only applies to tones measured at 1 kHz. This is problematic because our ability to hear doesn’t only derive from the intensity of the sound, but also with the sound’s frequency, or pitch. Human hearing becomes much less sensitive at frequencies below 1 kHz, making the sound pressure we can hear increase 1,000 times. However, for frequencies just above 1 kHz, our hearing threshold can be -9 dbSPL.

So the quietest sound a human can hear, while officially 0 decibels, is actually dependent on the sound’s pitch and the person’s ability to hear.

Protect Your Home at Any Decibel Level With Soundproof Cow

Soundproof Cow wants to protect you from the quietest sounds you don’t want to hear as well as the loudest. We offer Free Acoustic Analysis and Forever Sales to all military veterans and active service members. We have a wide range of soundproofing and sound-absorbing materials so you can keep any unwanted noise out of your life.

We’re so confident in our sound-deadening products and quality customer service that if you’re not 100% satisfied with our product, we’ll do everything in our power to right it. We strive to make every sale unique and want to work with you to find the soundproofing that’s right for your home or business.

No matter the level of decibels or herds… er, hertz, we won’t steer you wrong. Contact us today with any questions you may have about our products.

wave designAuthor

About Kellen Beaver

Soundproof Cow Representative Kellen

Kellen has been a member of the sales team for over a decade. Prior to delving into the soundproofing realm, he was a jack of all trades in the service industry, working both front and back of the house jobs to various degrees. This diversity in experience makes it easy to relate to the needs of a large customer base. He understands noisy environments as well as the importance of aesthetics in a space. Adding something that doesn’t fit the look can be intrusive, so knowing that acoustical needs must fit the interior design is something he’s become very well-versed in. Most of this planning comes from working with both the owner/operators as well as their design team and architects. He has been able to adapt his knowledge in the restaurant industry into projects involving schools, office buildings and large medical facilities when the situation calls for it.

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