Are frequencies (always?) intervallscaled?

Dear All,

My basic question is, whether a variable that contains frequency data can be considered as interval scaled?

Some more information on my data:

My data set contains 14 variables per participant (60 participants, in three independent groups of treatment). Each of the 14 variables contains ordinal data (three levels: -1=impairement; 0=no change; 1=improvement).
Based on theoretical considerations, I expect that there is an improvement across the parameters for some groups. I therefore would like to create three new variable that contains the number of impairements (VAR 1), number of improvements (VAR 3), number of "no changes" (VAR 2). My question is, whether these new variables, which are based on ordinal data, are now interval scaled?

If not, what determines the scale level of variables containing frequency data?

I am really looking forward to your replies.