The sensation of improving snoring after UPPP is not subjective, actually the sound improves, the problem is that the measurement of snoring is done with subjective methods like analogue visual scales or other type of scales. Nevertheless, although it's a subjective way of measuring, it doesn't mean that the results are subjective.

In fact "a type of UPPP" done with radio frequency (RF) has a randomized controlled clinical trial with placebo (sham RF) and they probe that RF had better results than sham-RF. SEE THIS: Radiofrequency surgery of the soft palate in the treatment of snoring. A placebo-controlled trial.

Stuck BA, Sauter A, Hörmann K, Verse T, Maurer JT.

Sleep. 2005 Jul;28(7):847-50.

Besides the results, although not as good as in the beginning, they stay over the time in a lesser scale that at the beginning of the treatment. SEE THIS: Radiofrequency of the soft palate for sleep-disordered breathing: a 6-year follow-up study.

De Kermadec H, Blumen MB, Engalenc D, Vezina JP, Chabolle F.

Eur Ann Otorhinolaryngol Head Neck Dis. 2014 Feb;131(1):27-31. doi: 10.1016/j.anorl.2013.04.005. Epub 2014 Jan 16.

The problem with surgery is that is impossible to perform double blind clinical trials, and results are not so "clean" and objective as with CPAP or a pill.

Besides, UPPP objectively has results by improving AHI and other PSG findings like nadir O2. SEE this article where surgery vs wait and see it's compared: SKUP3 randomised controlled trial: polysomnographic results after uvulopalatopharyngoplasty in selected patients with obstructive sleep apnoea.

Browaldh N, Nerfeldt P, Lysdahl M, Bring J, Friberg D.

Thorax. 2013 Sep;68(9):846-53. doi: 10.1136/thoraxjnl-2012-202610. Epub 2013 May 5.

Nevertheless UPPP cannot improve to everyone, there are different areas of vibration in the upper airway like the palate, tongue base, lateral pharyngeal walls and even posterior wall in some patients, and UPPP only touches palate and maybe the upper part of the lateral walls, besides surgical technique connote remove the whole structure that vibrates, the second effects would be awful, so although you can stiff the palate, there is still palate that can vibrate.

But I insist, after UPPP, patients improve their snoring.

UPPP is not a very successful surgery. My feeling is that if there is reduction in redundant tissue, there may be less subjective sense of discomfort in the throat. It does not change the opening significantly.

Let me see if I understand your question.

Are you asking why is there *subjective* improvement in cases where there is no *objective* improvement? If that is your question, then my answer is that the relationship between objective snoring intensity and subjective snoring is highly variable. Most studies have not rigorously measured snoring to know whether snoring objectively has improved. Following surgery, the acoustics of snoring might also be changed in ways that might be perceived as less bothersome - even if the same dB level is present. (Pevernagie et al. The acoustics of snoring. Sleep Medicine Reviews 14 (2010) 131-144).

A recurring theme of snoring and OSA is that subjective symptoms correlate quite poorly with objective measurements of snoring or OSA severity. By extension, the subjective response to therapy is not easily predictable by severity characteristics of OSA (see Kingshott et al. Predictors of improvements in daytime function outcomes with CPAP therapy. Am J Respir Crit Care Med. 2000 Mar;161(3 Pt 1):866-71.) The same holds true for snoring and is even more confounded by the fact that snoring is usually appreciated only by the bed partner. (Wiggins CL et al. Comparison of self and spouse reports of snoring and other symptoms associated with sleep apnea

syndrome. Sleep 1990; 13: 245—252.)

While the therapeutic to response to UPPP for OSA is inconsistent, there are cases where it abolishes/mitigates OSA and therefore snoring, in which case the subjective improvement is rooted in objective improvement.