minecraft-bedrock-json-schemas/source/resource/ui/elements/properties/sound_volume.json

{
  "title": "Sound Volume",
  "description": "The volume of the sound.",
  "anyOf": [
    {
      "type": "number",
      "minimum": 0,
      "maximum": 1
    },
    {
      "$ref": "../../general/item_ref.json"
    }
  ]
}