Hey, I wanted to know if there was a way to do custom sounds for animals (I am looking for "mooEvent" for example and then play sound when this event is called). Thank you.

Is the animal's class yours or do you want to modify the existing animal's sound?

If it's the former then you can return your custom sound event in EntityLiving#getAmbientSound(for sounds that happen over time), EntityLivingBase#getHurtSound(for the sound the entity makes when hurt) and EntityLivingBase#getDeathSound(for sound that plays on death).

If the entity isn't yours then subscribe to a PlaySoundEvent, check whether the sound playing is the one you want to replace and if it is one use PlaySoundEvent#setResultSound to change the sound.

Ok thank you. I'll try this ! (2nd case)

It works well with this code for those who are interested in

@EventBusSubscriber
public class SoundsHandler {
		
	@SubscribeEvent
	public static void onSoundPlayed(PlaySoundAtEntityEvent  event)
	{				
		if(event.getSound() == SoundEvents.ENTITY_COW_AMBIENT)
		{
			event.setSound(SoundInit.ENTITY_COW_AMBIENT);
		}
	}

}

where SoundInit.ENTITY_COW_AMBIENT is your custom sound. Thank you.