Question- how to get noise from FilmPass() like in Chapter Eleven 02-post-processing-simple-passes.html?

[dman777]

From Chapter Eleven 02-post-processing-simple-passes.html, where is the noise coming from in var effectFilm = new THREE.FilmPass(0.8, 0.325, 256, false);?

The orbiting is not causing the noise effect, because when I remove the orbit animation, it is still there. It's not coming from the textures, because when I remove them, the noise effect is still there.

I've tried using THREE.FilmPass() in my own experiment and I can not make the noise effect. Instead, I just get the normal scan line effect without the noise.

    var renderPass = new THREE.RenderPass(scene, camera);
    var effectFilm = new THREE.FilmPass();
    effectFilm.uniforms.grayscale.value = false;
    effectFilm.uniforms.nIntensity.value = 3;
    effectFilm.uniforms.sIntensity.value = .3;
    effectFilm.uniforms.sCount.value = 2048;

    effectFilm.renderToScreen = true;

    var composer = new THREE.EffectComposer(renderer);
    composer.addPass(renderPass);
    composer.addPass(effectFilm);