In human society, much of the quality of life is dependent upon the hearing mechanism. In a society based on telepathy, it must not be assumed that the aliens have lost their ability to hear through eons of evolution; their communicative abilities might well have evolved and developed as a normal part of their genetics (if, indeed, they have genetics). Thus, the non-hearing society would not have the benefit of the aesthetic world that comes with hearing. All musical forms (and perhaps dance), which enriches and fulfills our lives in innumerable ways and which are some of the earliest and most important artistic expressions for all human societies, would be nonexistent in a telepathic society. It means that the aliens might have no built-in aesthetic sense and/or inner emotions satisfied by rhythmic and melodic notes produced by patterned tones and beats.
The normal visual cues that both deaf and hearing humans rely upon for complete communication are, in telepathic communication, not present. The aliens do not use their hands to gesture expressively. The subtle and wide range of expression that humans can use — cynicism, irony, sarcasm, drama — seems to be limited for the aliens, and the range of communicative expression that comes from subtle facial movements is almost nonexistent. Abductees do not report the use of “body language” to communicate subtleties and nuance, although it is possible that aliens may have incorporated this into their telepathic communication without abductees being able to recognize it.