In a recent blog article over at James Boldin’s Horn World blog, James discusses a recent visit to the University of Louisiana-Monroe by Dr. Eldon Matlick, who is the Horn Professor at the University of Oklahoma.
His blog article briefly covers some of the topics that Dr. Matlick discussed with the ULM Horn Studio, and one that I found most interesting was the procedure that Dr. Matlick used to tune a horn.
From James’ article:
Here is the procedure Dr. Matlick suggested for tuning the double horn. Fingerings in [ ] assume a standard double horn, standing in the key of F.
1. Play third-space C  (adjust F tuning slide)
2. Play third-space C  (adjust first valve slide on the F side)
3. Play third-line B-flat , then match [T1] (adjust first valve slide on the B-flat side)
4. Play fourth-line D , then match with [T12] (adjust second valve slide on the B-flat side)
5. Play third-line B-natural [T2], then match with  (adjust second valve slide on the F side)
6. Play second space A , tune, then match with [T12]
7. Play second space A [T3], tune slightly low (adjust third valve on B-flat side), then match with  (adjust third valve slide on F side)
The steps are for a “normal” double horn, standing in F, with no independent Bb tuning slide. His tuning procedure (which you can find in the article linked above) is interesting in that he not only uses the “normal” 8th and 6th partials to tune the horn, he also uses the 9th partial on some fingerings.
I wrote an article about tuning the double horn, and while I still like my approach, Dr. Matlick’s definitely seems a bit faster and maybe a bit more elegant while still being thorough and covering all the main single and combination fingerings.
I’ve been trying to learn a new horn I purchased a few months ago, and I’ll certainly be giving this system a try on that instrument.
In the mean time, there are definitely some very interesting tidbits about Dr. Matlick’s pedagogical approach to read about, and if you haven’t read my tuning page (along with slide reference images) you may want to check that out if you have issues playing in-tune.