Buddhist ritual song from Japan
The overtones in Shōmyō are even more pronounced than in Tibetan monk singing. They are so clear in solo singing that you can write them down in notes. And the overtones occur reproducibly in the same syllables. This means at least that the second formant for identical vowels is very precisely adjusted and always adapted to the partials of the voice. Whether the overtones are conscious to the singer, or whether they are sung in a targeted way, I could not find out from the literature so far. If you can tell me more about it, please feel free to comment.
For the faculty of hearing is beyond All thought, beyond both mind and body.