The two main distinctive features are voicing and aspiration. A characteristic and unusual trait of Nibel is that aspiration is distinguished in almost all consonants with the exception of some fricatives. Likewise, the voicing opposition carries over to the liquids and nasal. Nibel aspirates, both voiced and voiceless, are characterized by clearly audible breathy voice on a following vowel.
Only about half of the consonants, termed "primary", are found in citation forms. These are marked in bold in the table. The rest ("secondary consonants") occur only as results of consonant mutation; however, mutation may also result in primary consonants.