"By voice" abilities are for all intensive purposes voice delivered spells with an area of effect equal to the range of the voice.
Voice range is defined by the distance at which you would be able to hear the caster clearly. Essentially, if you can make out what was yelled, you are in the effect area.
Being that this is not a weapon or packet delivered attack, applicable defenses are a bit different.
- Dodge is an invalid defense (you can't dodge a voice)
- Spell Parry is an invalid defense (you can't parry a voice)
- All other defensives apply. Spell Shield, Reflect Magic, Elemental Shield, Poison Shield (it could happen) Cloak, Bane, Resist, Guard. I'm pretty sure that's all of them.
- Being in a Prison would make you No Effect to all "by voice" abilities.
With LoS abilities such as Fear, the caster is who you would need to break LoS with.
I apologize if this was not made known. By voice is one of the ones that are used so frequently across chapters that I forget it is not a rulebook delivery. I will also bring it up at opening ceremonies at our next event. Thank you Mike for bringing it up.
Edit: By voice is actually covered in the rule book on page 97 under Radius
Radius: Radius deliveries include traps,
contact poisons, and monster abilities such as
eye contact or sound of voice. Usually a Hold
is called when a radius attack takes place and
everyone partially within the radius is affected.
Radius attacks can never be Dodged or Evaded.