Sensitiveness
Part of speech: noun
Definition: The ability to perceive sensation. The ability to be aware of (and, usually, react with regard to) the feelings of others.
Sensitivity
Part of speech: noun
Definition: The quality of being sensitiveThe ability of an organism or organ to respond to external stimuliThe proportion of individuals in a population that will be correctly identified in a binary classification test.The degree of response of an instrument to a change in an input signal.The degree of response of a film etc. to light of a specified wavelength.
Example sentence: You could write a song about some kind of emotional problem you are having, but it would not be a good song, in my eyes, until it went through a period of sensitivity to a moment of clarity. Without that moment of clarity to contribute to the song, it's just complaining.