curl --request POST \
  --url https://api.example.com/frame_synthesis \
  --header 'Content-Type: application/json' \
  --data '
{
  "f0": [
    123
  ],
  "volume": [
    123
  ],
  "phonemes": [
    {
      "phoneme": "<string>",
      "frame_length": 123,
      "note_id": "<string>"
    }
  ],
  "volumeScale": 123,
  "outputSamplingRate": 123,
  "outputStereo": true
}
'

"<string>"