[mizuki-7]

Originally Posted by koumori

None of these tasks impacted her vocals. Her vocal quality is down to many different factors, but not at her taking part in things as a director or producer. It's likely vocal damage which is quite common for artists forced to sing outside of their normal range for years (Namie reported having permanent vocal damage after her PLAY tour, and Utada had damaged vocal chords after her Wild Life tour, as two similar examples)

What Ayu can do best for her voice is to keep practicing good vocal habits, lower the key on some of her tracks that are outside her natural range, and rest her vocal chords properly. At least, that's from my uneducated point of view
As I said before, I'm happy she's surrounding herself with people she trusts now and doesn't feel it's all down to her. I just don't think her workload is what directly impacted her vocals at all.

@Andrenekoi: Yeah, she really has innovated a lot of different ways to evaluate performances.

I agree with what you said but I still think that production is something demanding and tiring and can have an indirect impact on her whole condition.