Final answer:
The test described is used to assess nasal resonance in speech. No difference when the nares are pinched suggests hypernasality, while a big difference indicates a possible nasal obstruction.
Step-by-step explanation:
The exercise described in the question relates to assessing a patient's nasal resonance when speaking, which is important in identifying certain speech disorders or nasal obstructions. When the patient is asked to repeat sentences with their nostrils pinched closed, we can observe changes in the quality of their speech.
If there is no difference between the nose held and nose released, it suggests that the nasal passages are not contributing to the resonance of speech, which could point towards hypernasality due to a problem with the velopharyngeal mechanism. This mechanism normally closes off the nasal passages during the production of most speech sounds. If there is a big difference when the nares are pinched, it suggests that the nasal passages are typically contributing to speech resonance, so the problem could be related to a nasal obstruction.