Background and objective: The present study provides reference data on the auditory discrimination of phonemes in a population normal-hearing of native Spanish-speaking from Chile. The objective is to determine if the lengthening of phonemes affects the ability of auditory discrimination. Participants, materials and method: The sample consisted of 40 subjects between the ages of 19 and 36 who were subjected to an auditory discrimination task of a series of 35 pairs of words. These words presented differences with respect to the duration of one of the consonants phonemes. To achieve the objectives, pairs of words without modifying any phoneme were compared with those in which the duration of the phoneme was doubled (2 x), tripled (3 x) and quintupled (5 x), in addition to the comparison intercategories. Results: The results show that the subjects have difficulty discriminating between phonemes that have the smallest acoustic differences in duration, especially when comparing the phoneme that is double (2 x) and the phoneme that is triple (3 x) their natural duration. These results are also observed when comparing by specific type of phoneme, since in all (/s/, /n/, /t/ and /ʝ/) except /r/, the comparison that presented the most difficulty was that of the word with the phoneme is felt at double and triple the natural duration. Conclusion: The perceptive capacity of the subjects decreases to the extent that the stimuli are more similar in their duration.