Incoherent.  Is this not the word you use when you cannot understand someone for they are making no sense?  There are various things that can cause one to become incoherent:  mental confusion, ingested substances, fear, lack of focus … Coherence is necessary to communicate not only in this earthly realm, but most especially with the so-called higher realms.  How do you become coherent?  Cleanse the energetic body regularly of dissonant energy, find balance in your life, become centered, heal emotional wounds, practice presence … all of these lead to a greater ability to get in touch with other aspects of the Self.  Become coherent at will and you will connect.