Splitting S1 Site

: An S4 is a low-frequency sound occurring just before S1. Clinicians differentiate them by pitch; the initial sound in an S4-S1 pair is lower in frequency than the second, whereas in a split S1, both components typically share a similar pitch.

For more complex splitting, you can use the re.split() function from Python's re (regular expression) module: splitting s1

You can also specify a maximum number of splits: : An S4 is a low-frequency sound occurring just before S1