README.md

A wav file is a file with an audio header, then slices of pcm audio. To create a wav file from PCM, you need to add a wav header with the correct sample rate

pcm-to-wav.js

// npm install waveheader

const fs = require("fs");
const header = require("waveheader");

const filename = 'file.wav';

fs.writeFileSync(filename, header(0, {sampleRate: "16000"}); // 16000 khz
fs.appendFileSync(filename, fs.readFileSync('audio.pcm'));