In Chamorro, a typically neutralized contrast between mid and high vowels is preserved before intervocalic laryngeals. This preservation of contrast is shown to be an instance of patterned exceptionality. Rather than being a result of syllable structure or the typical lowering pattern of high to mid vowels in Chamorro, this exceptionality is instead conditioned by perceptual factors. The phonetic context provided by intervocalic laryngeals provides external cues pertaining to the quality of the preceding vowel, enabling the preservation of underlying contrast. This paper will demonstrate that laryngeals allow more robust acoustic information for perceiving vowel height (F1) when compared to supralaryngeal consonants. The continuation of vocalic F1 into and through the laryngeal provides more cues to the preceding vowel’s quality, allowing an underlying mid-high contrast to surface faithfully in this “exceptional” environment. This supports theories that integrate phonetic information into the synchronic phonology. The licensing of contrast provided by intervocalic laryngeals carries with it both typological and experimental predictions regarding the patterning of laryngeal consonants and the perceptual environment they provide.