Your article is in great shape. The pictures, graphs, headings and links to larger articles makes for a complete wikipedia article. Your tone is impersonal and detached and does not try to put forth an argument; rather, it is simply providing the facts, which is what we'd expect from a wikipedia article
I would suggest perhaps adding a bit more context to a few of the terms you use. While you provide links for the more complicated terms, it might be useful to give a quick explanation or definition as to what they mean. I understand wanting to keep the text brief and to the point, but as the Wikipedia: Writing Better Articles suggests, you should try and find a balance "between comprehensibility and detail so that readers can gain information from the article." (See https://en.wikipedia.org/wiki/Wikipedia:Writing_better_articles#Evaluating_context). A good question to ask is if a layperson was reading the article, particularly if it was printed out, would they be able to understand everything you are saying? For example, under the heading 'Soprano Voice', consider explain exactly how the mouth creates acoustic impedance.
You make good use of interlinking your article with other Wikipedia articles. However, beware that you are not overdoing it. For example, you interlink the words "opera", "soprano", "frequencies" on multiple occasions. Because of the short nature of our articles, it is not necessary to link it more than once.
You may have a different opinion on this than I do, but I am not quite sure what the purpose of the subscript symbols are in your article (such as "The fundamental frequency, f0,..."). Typically, it would be necessary to do this if you had an equation and wanted to assign meaning to the variables. On the other hand, it could also be used as a shorthand for future use (i.e., using f0 instead of saying fundamental frequency) but you seem to prefer using the full term. You do use them as shorthands once ("the soprano singer needs to tune R1 to match f0 in order to keep the singer's formant"), however in this case I believe it might be clearer to the audience if you simply typed out resonant frequency and fundamental frequency.
This is just a minor tweak, but the in-text footnotes (the superscript numbers) should come after the punctuation. E.g., Example 1.1 ; instead of Example 11.
