For a two-paragraph historical narrative of the dominant ninth chord in European and European-influenced music, see this post: link.
I have published an updated index to this blog and to essays about scale degree ^6 and the dominant ninth chord on the Texas ScholarWorks platform. Here is the link. The date for this was November 5, 2024. I have made several posts since then; please see individual blog entries for those.
For a list of all the essays I've posted to Texas ScholarWorks, go to the front page of the UT Faculty/Researcher Works section: link. If you click on Filters/Author, my name will come up as one of the most frequent contributors.
On 18 December 2024, I published the fourth and last part in my most recent series: Dominant Ninth Harmonies in Music from 1900 to 1925, Part 4. Here is the link.
In the final sentences of the two-paragraph historical narrative, I wrote that "already by 1920 the dominant major-ninth sound was considered passé by younger concert composers and was often actively avoided." Two posts on 5 December 2025 explored this idea with music by Paul Creston, William Schuman, and Robert Muczynski. In general I rely on music in the public domain and on what is legally offered online, and thus it is difficult for me to survey work after 1930, the current copyright barrier year in the United States. I visited a local research library for access to these pieces and made my presentations according to fair use practices.