Why do English speakers sometimes raise the pitch of their voices when not asking a question?

Question

When recording myself, I found that I sometimes raised the pitch of my voice when not asking a question, and not when asking a question. Why is this?

Answer 1

There is a practice, called 'uptalking', or 'upspeaking', alleged to have originated independently in the western USA ('Valley Speak' has been implicated), and also in Australasia (New Zealand has been suggested).

The high rising terminal (HRT), also known as upspeak, uptalk, rising inflection, upward inflection, or high rising intonation (HRI), is a feature of some variants of English where declarative sentence clauses end with a rising-pitch intonation, until the end of the sentence where a falling-pitch is applied.

High Rising Terminal (Wikipedia)

Final rising pitch – popularly known as “uptalk” – is an intonation pattern that involves rising pitch at the end of a sentence. It has been documented throughout the English-speaking world: in the US, Australia, and New Zealand; it has also been documented among ELT students.

Uptalk - myth and fact (Cambridge ELT)

Many native speakers (especially older ones) find uptalking annoying or irritating, although it is not as new as many suppose.

Answer 2

English vocabulary, pronunciation, inconsistency, and elocution provide rich opportunities for expression. It’s a blessing, that’s all.

Edit

As was requested in a comment, your variations are part and parcel of your desired expression.