What is the test for reversal of a motion where a defendant is denied access to a defense interpreter?

Mindful of the fact this court held in People v. Carreon (1984) 151 Cal.App.3d 559, 198 Cal.Rptr. 843 that "A violation of [the right to a defense interpreter] is reversible error only if an informed speculation by the reviewing court reveals that the defendant's right to effective representation was prejudicially affected under the peculiar facts of the case," (id., at p. 582, 198 Cal.Rptr. 843) defendant argues alternatively that application of the standard developed in Carreon to the instant case also mandates reversal.