Is all hearing protection the same? No, so the easiest way to compare products is to use a rating system.

In the United States, the system is the NRR [Noise Reduction Rating]. The current range of NRR extends from 0 to 33 decibels.

The Canadian system, based on levels (A-C) or grades (1-4), is explained at http://www2.worksafebc.com/pdfs/hearing/hearing_protection_devices_selection.pdf

Check out http://www.cdc.gov/niosh/topics/noise/ for a great website that includes the Hearing Protector Compendium, a searchable database for selecting hearing protectors available from US hearing protector manufacturers, and NIOSH Power Tools Database, information covering sound power levels and sound pressure levels and downloadable exposure files.

The Canadian Centre for Occupational Health & Safety describes hearing protectors at http://www.ccohs.ca/oshanswers/prevention/ppe/ear_prot.html

For more information and rating from the European Union, Australia, and New Zealand, see “Sound Source: Understanding Ratings” http://www.hearforever.org/tools-to-learn/sound-source-understanding-ratings