What Is the Sound Pressure Level of a Lawnmower?

Lawnmower Sound Pressure Level

• Sound pressure level is measured in decibels. Most lawnmowers emit a sound pressure level of about 90 decibels. This is on a scale at which 0 decibels is the threshold of hearing and 10 decibels is a barely audible whisper. People who are exposed to decibel levels of 85 or higher for more than eight hours on a consistent basis will gradually lose their hearing. Those who mow lawns can combat this by wearing earplugs or other ear protection.

Hearing Loss Risk Threshold

• The hearing loss risk threshold is around 85 decibels. This means that some sounds -- such as a noisy restaurant, a vacuum cleaner, city traffic, a hairdryer and alarm clock -- do not put you at risk for hearing loss, if exposure isn't beyond reasonable limits. Each of these items has a sound pressure level between 50 and 80 decibels. Not all sounds that cause hearing loss cause immediate discomfort. For example, although your lawnmower may cause hearing loss when it is operated for extended periods of time, you may not feel pain as you use it.

Discomfort Threshold

• Some sounds cause discomfort immediately upon hearing them. These sounds include an air-raid siren, a smoke alarm, live rock music, a horn from an automobile or a clap of thunder. Generally speaking, any sound that emits a sound pressure level of more than 100 decibels may cause discomfort.

Pain Threshold

• The threshold between discomfort and pain is a sound pressure level of about 130 decibels. A gunshot -- which is about 140 decibels -- is an example of a sound that can cause immediate ear pain. Other similar sounds include rocket-launching pad noises and the sound you hear if you are within feet of an exploding cannon.