What do rock concerts, jet planes, and boom cars have in common? They all produce sounds within the 140-145 decibel range. At this site, an interactive table demonstrates real-world sounds ranging from 0-140 decibels. You can compare sounds made by mosquitoes, snowmobiles, drills, power saws, and other objects. A Flash-based "interactive sound ruler" measures the decibels associated with each type of sound and identifies the decibel range in which exposure to these sounds becomes harmful.
This Flash-based site provides a great real-world context for understanding the way sounds and decibels are related. Students are given a combined visual approach, via the interactive ruler, and an auditory approach, via sounds of diesel engines, rock bands, etc. This is a good activity for younger, auditory learners because the science is not too difficult. Students can apply this knowledge at home by making a list of loud and soft sounds.