Hi and thanks for responding to my BN check request!
I used the above-mentioned Spectro program and the sound quality problem is indeed present upon checking the main audio file. Now the suggested 128kbps mp3 is applied as the main audio.
This suggestion certainly helped me learnt how to check for the sound quality and its audio cut-off (to reduce the beatmap file size while keeping the main audio quality). Thank you so much for taking your time here ^_^
(Listing the changes I made)
7/21/2020
Normal
1) Added a note in 03:06:740 (186740|1) for consistency sake.
Hard
1) Changed the notes in 02:47:858, 02:48:564, 02:59:152, 02:59:858 to hand to follow the pattern in 01:17:152 (77152|3,77152|2,77328|0,77505|3,77505|0,77505|1,77858|0,77858|1,78034|3,78211|3,78211|2,78211|0)
2) Added a note in 00:57:034 (57034|0) for consistency sake.
??!!! ehh that's true.
https://osu.ppy.sh/help/wiki/Ranking_Criteria
"Active hitsounds must use the .wav or .ogg file formats. .mp3 files have slight delays, and therefore are reserved only for longer passive hitsounds, such as ambient noises."
I thought there an ongoing proposal about this issue. (but it's actually about using .ogg as the main audio source) (https://osu.ppy.sh/community/forums/topics/1021547)
While there's actually an older thread allowing .ogg as hitsound
(https://osu.ppy.sh/community/forums/topics/945413)
(https://github.com/ppy/osu-wiki/pull/2453)
Fortunately I have the old version I can revert back into lol.
UH OH, I used .ogg file to conserve the file size without realising it's unrankable...
Fixes
1) Changed all .ogg audio files to .wav
2) Changed .ogg suffixes in the hitsounds of all difficulties to .wav
I think I'll take some the relevant tags from this ranked mapset (https://osu.ppy.sh/beatmapsets/1079554#mania/2267030), since this is also a nanawo akari song covered by another hololive member