"In previous version, I notice sprintf would ouput without the apostrophe, whereas now it is (ie 'conditon1' as oppose condition1)"
SPRINTF has never added extra single quotes onto text data (unless they are in the text itself). You are confusing the data content with how data are displayed. A few years back (around 2016?) MATLAB changed how it displayed character vectors (to show them with single quotes), but this is unrelated to SPRINTF() and makes absolutely no difference to the content of the character vector. The displaying using single quotes is explained here:
"...some of the code I once used doesn't seem to work as I once used"
A quick perusal of the help going back to 2009 shows SOUND() has never accepted a character vector input.
"I have a bunch of variables that are my sound files which play perfectly fine when I run them through a standard command ie sound(condition1,44100)"
Then the actual source of your error is bad data design, specifically forcing pseudo-indices into variable names:
The simple solution is to use actual indexing, just like MATLAB is designed for and just as the documentation shows:
"Any help would be gratefully received. "
Never force meta-data into variable names.
