Spl Distance

{
  "asOf": "2026-10-11T14:38:35.934Z",
  "changeDb": -18.0618,
  "dbPerDoubling": 6.0206,
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "distanceM": 8,
  "intensityWPerM2": 0.000015624999999999987,
  "levelAtReferenceDb": 90,
  "levelDb": 71.9382,
  "notChecked": [
    "air absorption, which grows with frequency and distance (several dB per 100 m at high frequencies)",
    "reflections, reverberation and diffraction (indoors the level stops falling near the reverberant level)",
    "…3 more"
  ],
  "pressurePa": 0.079056942,
  "reasons": [
    "Inverse-square law: the level falls 20 log10(r2/r1) dB.",
    "Ideal free field: real rooms and air absorption change this."
  ],
  "referenceDistanceM": 1,
  "soundPowerLevelPointSourceDb": 100.9921,
  "source": "Free-field spherical (20 log10) and cylindrical (10 log10) spreading; p0 = 20 micropascal; I0 = 1e-12 W/m2, computed locally",
  "spreading": "point",
  "summary": "90 dB at 1 m becomes 71.938 dB at 8 m (point source, 6.02 dB per doubling of distance).",
  "verdict": "COMPUTED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://audio-calc.x402tookit.com/spl-distance?distance=8&level=90&refDistance=1&source=point'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://audio-calc.x402tookit.com/spl-distance?distance=8&level=90&refDistance=1&source=point' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Faudio-calc.x402tookit.com%2Fspl-distance
const res = await pay("https://audio-calc.x402tookit.com/spl-distance?distance=8&level=90&refDistance=1&source=point");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://audio-calc.x402tookit.com/spl-distance?distance=8&level=90&refDistance=1&source=point")
    print(res.status_code, res.text)