The video at the link below contains the phrase "une belle sonnance" in the subtitles at about 15:37. 'Sonnance' isn't in any of my dictionaries and I'm drawing a blank on Reverso and Linguee as well. The phrase "une belle sonnance" throws up only two google results for me, as does "une belle sonance". The sense in these results seems to be "an attractive sound".
What I hear in the video certainly sounds like 'sonnance', which is evidently what the subtitler heard as well, so I'm wondering whether the speaker perhaps means something else, for example "une belle assonance".
Any ideas? Thanks in advance.