[2] As of 1993, Huallaga Quechua was spoken monolingually by 66% of the population of its native speakers,[1] the remainder of whom are bilingual primarily in Spanish.

While communication in Quechua still maintains its cultural value within communities, Spanish is preferred for inter-community use.

According to David Weber, the UCLA linguist who published the 1989 grammar of Huallaga Quechua, some now-common phones in Huallaga Quechua are only present in Spanish loanwords and sound-symbolic words, but the language seems to have had no structural influence from Spanish beyond phones and vocabulary.

[2] Voiced stops occur mainly in sound-symbolic words, e.g. bunruru-, 'to rumble [as thunder]', and words borrowed from Spanish, e.g. aabi, 'small bird', from Spanish ave.[2] Huallaga Quechua notably lacks the ejectives and contrastive aspiration of stops present in other Quechua dialects, such as the Cuzco dialect.

The original three-vowel inventory, contrasting only height and backness, is typical across Quechua dialects.

Fine semantic differences may be expressed by vowel length: /kawa-live-ra-PST-:-1-t͡ʃu/NEG→ [kawara:t͡ʃu] /kawa- ra- :- t͡ʃu/live- PST- 1- NEG'I did not live'/kawa-live-:-1-raq-yet-t͡ʃu/NEG→ [kawa:ra:t͡ʃu] /kawa- :- raq- t͡ʃu/live- 1- yet- NEG'I still don't live'In Spanish loanwords, Huallaga Quechua often renders accented syllable stress as vowel length, even if the stress does not fall on the penult.

The maximal syllable structure of Huallaga Quechua is CVC, with V, VC, and CV all being permissible as well.

Two processes, related diachronically, may be hypothesized to explain the development of -ni- insertion and its potential eventual generalization: In Ia, A noun root gains a possessive suffix at the lexical level, feeding IIa, in which -ni- is inserted between each bimoraic-final root and pre-syllable-boundary consonant-initial possessive suffix.