What are some alternatives?
When comparing Digital Level Meter and AudioTool, you can also consider the following products
Sound Meter - Professional sound level meter in your pocket! Features: ------- ¦ direct reading in dB
LMMS - Make music with a free, cross-platform tool
Sound Level Meter - You can measure the environmental noise in decibels.
Ardour - Record, edit, and mix on Linux, Mac OS X, and Windows.