Another approach that may be more readable is simple type conversion. I've added a replacement function to cover instances where people may enter European decimals:
>>> for possibility in "Current Level: -13.2 db or 14,2 or 3".split():
... try:
... str(float(possibility.replace(',', '.')))
... except ValueError:
... pass
'-13.2'
'14.2'
'3.0'
This has disadvantages too however. If someone types in "1,000", this will be converted to 1. Also, it assumes that people will be inputting with whitespace between words. This is not the case with other languages, such as Chinese.
