curl --request POST \
  --url https://api.iotools.cloud/v1/tool/decibel-converter \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "refType": "spl",
  "value": "85",
  "unitSpl": "dbspl"
}
'

{
  "tool": "decibel-converter",
  "tool_version": "1.0.1",
  "outputs": {
    "results": [
      {
        "quantity": "dB SPL",
        "value": "85 dB SPL"
      },
      {
        "quantity": "Sound Pressure",
        "value": "0.3557 Pa"
      },
      {
        "quantity": "Pressure Ratio (p / p₀)",
        "value": "17782.7941"
      },
      {
        "quantity": "Intensity Ratio (I / I₀)",
        "value": "3.1623e+8"
      }
    ],
    "reference": [
      {
        "source": "Threshold of hearing",
        "level": "0 dB"
      },
      {
        "source": "Rustling leaves",
        "level": "10 dB"
      },
      {
        "source": "Whisper at 1 m",
        "level": "30 dB"
      },
      {
        "source": "Quiet library / office",
        "level": "40 dB"
      },
      {
        "source": "Normal conversation",
        "level": "60 dB"
      },
      {
        "source": "Busy traffic",
        "level": "75 dB"
      },
      {
        "source": "Vacuum cleaner",
        "level": "80 dB"
      },
      {
        "source": "Heavy traffic / lawn mower",
        "level": "90 dB"
      },
      {
        "source": "Subway / motorcycle",
        "level": "100 dB"
      },
      {
        "source": "Live rock concert",
        "level": "110 dB"
      },
      {
        "source": "Threshold of pain",
        "level": "130 dB"
      },
      {
        "source": "Jet engine at 30 m",
        "level": "140 dB"
      },
      {
        "source": "Firearm muzzle blast",
        "level": "160 dB"
      }
    ],
    "formula": "Sound Pressure Level (reference p₀ = 20 µPa)\n\ndB SPL = 20 · log₁₀(p / p₀)\np = p₀ · 10^(dB SPL / 20)\nPressure Ratio = p / p₀\nIntensity Ratio (I / I₀) = (p / p₀)²"
  },
  "credits_used": 3,
  "credits_remaining": null
}