Introducing the Decibel

Noise-induced hearing loss (NIHL) is one of the most common forms of hearing impairment. In order to prevent it, we need to understand what level of exposure to loud noises is safe. But how can you measure something as abstract as a sound’s volume? The solution audiologists use is an interesting unit of measurement called a decibel (abbreviated as dB).

Most people have heard of decibels, and know that more decibels mean a louder noise. Beyond that, however, the decibel is widely misunderstood. We hope you find the following introduction helpful in understanding how the decibel system works. For further information about hearing health, call HearingPlanet’s hearing aid specialists at 1-800-432-7669.

Ratios versus Amounts

The important thing to know about the decibel is that it represents a ratio, not an amount. In other words, there is not an amount of energy called a decibel that can be added or subtracted to achieve a different volume. Instead, a decibel compares the loudness of two different sounds. When we want to determine a noise’s decibel level, we must compare it to a certain predetermined baseline.

When measuring a sound’s intensity, audiologists use a baseline they call “zero decibels.” This is the lowest volume that a sensitive human ear can hear. There is no mathematical reason to call this volume zero decibels; audiologists have simply selected it for convenience. The decibel level of a sound tells you how many times louder it is than the lowest audible noise.

Now, does that mean a 5 dB sound is 5 times louder than zero decibels? Actually, no. The formula for determining decibel levels uses a mathematical function called a logarithm, which follows very different rules from a linear scale.

Understanding Decibel Levels

You do not need to know everything about logarithms to understand a decibel level. All you need to know is that a 10 dB sound is 10 times more intense than a zero decibel sound. Therefore, a 20 dB sound is 100 times more intense than zero (10 x 10). A 30 dB sound is actually 1,000 times zero dB. It may sound confusing, but just remember that you are not working with a linear scale.

The average human range of hearing is about zero decibels to 120 decibels. Past this point, sound becomes painfully loud and may cause permanent damage to the ears.

Contact a Hearing Health Consultant

HearingPlanet’s mission is to help hearing impaired people find the information and technology they need. To speak with a HearingPlanet hearing aid professionals, contact us today at 1-800-432-7669.