Foghorn Noise Levels

This weekend I visited Portland, Maine. I went to the Portland Head Light (which is essentially a lighthouse) located at Fort Williams Park. For a little bit of background, the Portland Head Light was first constructed in 1787 with $750 from the General Court of Massachusetts to protect Portland from British attacks. Another $1500 was added for the completion of the lighthouse in 1791. You can read more on the history of the lighthouse here.

While visiting the lighthouse, the fog horn was going off every 10 seconds. It was a rainy day and there was a lot of fog in the area. Of course, I had to go as close as I could using my Decibel app and capture how loud the foghorn was. You know, for science.

The maximum reading I captured was 107 dBa. Of course, my phone is not calibrated but that is approximately the level of intensity of the sound.

I am not really surprised at the loudness because the fog horn has a job to do: warn ships in foggy conditions that there is land near so they do not crash. It MUST be loud to be effective.

So to the right of the lighthouse is a building where the fog horn components are located. Here is a picture of what the door says on that building that houses the fog horn. They called it the Whistle House. Check out that warning label: Hazardous Noise may cause Hearing Loss. Ear Protection Required.

Now around the building walking towards the water is the actual fog horn. It was gated off but this is where I took my reading and captured 107 dBa as the max! Another great warning sign: Danger! High Intensity Fog Signal; Keep Away! As a safety professional, I had to know what the approximate noise level was! So I did not keep away as the sign said. But I was only there for about 20 seconds with my Decibel App, capturing two times when the horns went off.

Then I took a picture of around the building of the actual foghorn!

OK so 107 dBA… is that actually loud?

YES, it is loud! OSHA says that if you are exposed to noise levels above 85 dBA for an 8-hour time-weighted average, then you must go into a hearing protection program since this level of noise has the potential to cause hearing damage. If noise exposure is greater than 90 dBa, then you are required to wear hearing protection. Of course, this was a lighthouse for visitors, who only stay for minutes at a time, but the workers who work at the lighthouse could potentially be exposed to these types of levels if they are consistently working around the foghorn such as making lighthouse repairs, yard work, etc. To put the 107 dBa into perspective, a motorcycle at 25 feet away is around 90 dB and a normal car driving at 65 mph at 25 feet is 77 dB.

I know I was supposed to be enjoying the history but I had to take a second and capture how loud this foghorn really was. I am sure foghorns have only gotten louder since they were created but it is a great engineering control that is put in place to warn ships when there is fog! Foghorns have to be loud to be effective. If it was only 70 dBA, well, there would be a lot more sunken ships around the coasts…

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