Perceived Noise Reduction & Charting Noise with Decibels (dB)

Sound perception is an intriguing aspect of human physiology that allows us to interpret the auditory information in our environment. At the most basic level, sound is a form of energy that travels in waves. These waves, caused by the vibration of an object, move through a medium such as air, water, or a solid material, and are captured by our ears.

When these sound waves reach our ears, they cause our eardrums to vibrate. These vibrations are then converted into electrical signals by tiny hair cells in our inner ears and are transmitted to the brain via the auditory nerve. The brain then interprets these signals as distinct sounds, allowing us to recognize speech, music, environmental noises, and more.

However, not all sounds are perceived equally by the human ear. This brings us to the concept of sound intensity and how we perceive different levels of sound. Our ears perceive sound more accurately described by the logarithm of the intensity of a sound rather than the intensity of the sound directly. This logarithmic perception aligns with the inherent characteristics of the human ear, which can detect a vast range of sound intensities, from the faintest whisper to the roar of a jet engine.

Deciphering Decibels

In the context of sound, a decibel (dB) is a unit used to express the ratio between two physical quantities, usually amounts of acoustic or electric power. It is also used for measuring the relative loudness of sounds. In simpler terms, a decibel is a measure of sound pressure or energy and is used to quantify the intensity of a sound.

On the decibel scale, 0 dB is identified as the smallest audible sound, and it’s important to note that this scale is logarithmic, not linear. This means that each increase of 10 dB represents a tenfold increase in sound intensity. For example, a 20 dB sound is ten times more intense than a 10 dB sound.

One key takeaway about decibels is that even small increases in decibels can result in significantly louder sounds. Therefore, understanding and managing sound levels is crucial in various aspects of life, from protecting our hearing health to managing noise pollution in our environment.

To get a sense of the effects of sound pressure on the human body, one can consider examples of sounds at various decibel levels. For instance, a quiet conversation at home is around 50 dB, a lawn mower is about 90 dB, and a loud rock concert can reach up to 120 dB.

Decibel Chart: How To Measure Sound

The following decibel chart shows various dB levels and the corresponding reduction in actual sound pressure level (SPL) as well as the human perceived volume reduction for reducing noise levels.