If it is a calm, windless day I use a low volume call at all distances. If it is windy and you know that the sound is not going to be heard except downwind I use a loud call. Then when they get in to about 100 to 150 yards I switch to a softer call. This has been working for me for the last 50 years. I have many calls but for the soft but ducky sounds I use a Mallardtone or an old Lohman which are both wooden calls. These are what I considermy close in calls. I use a Duck Commander call or RNT or Primos for the times I need real volume. Everyone has their own opinions and ideas but this is what works for me. Good luck!!