Crunchy audio with effects

[honest breach]

I made a lowpassfilter effect for my audio when the player is underwater, but the audio sounds crunchy. With noise.

//CreateEvent
lowpass_filter = audio_effect_create(AudioEffectType.LPF2);

//StepEvent
if (swimming) {
    if !audio_bus_main.effects[0] != lowpass_filter {
        audio_bus_main.effects[0] = lowpass_filter
    }
} else {
    if (audio_bus_main.effects[0] = lowpass_filter) {
        var null_effect = audio_effect_create(AudioEffectType.Reverb1);
        null_effect.mix = 0
        audio_bus_main.effects[0] = null_effect;
    }
}

[vivid wind]

There's a double negative in your condition:
if !audio_bus_main.effects[0] != lowpass_filter which leads to it always being true if swimming. This replaces the low-pass filter instance with a new one each step. This essentially resets the filter's internal state each step which is what causes the crackle.

Also if you want to clear an effect, you can set the element in the effects array to undefined

Alternatively, you can keep the effect there all the time and bypass when it isn't needed. For example:

//CreateEvent
lowpass_filter = audio_effect_create(AudioEffectType.LPF2, { bypass: true });
audio_bus_main.effects[0] = lowpass_filter

//StepEvent
if (swimming) {
    lowpass_filter.bypass = false;
} else {
    lowpass_filter.bypass = true;
}