At least since the turn of the millennium, adolescents growing up in linguistically and culturally diverse neighborhoods of European cities have developed innovative ways of speaking, which are often referred to as "multiethnolectal". To investigate the phonetic features of multiethnolectal Swiss German, a research project is currently carried out in the city of Zurich. Forty-eight adolescents were recorded in different speaking styles, and in a subsequent perception experiment, these speakers were rated by other adolescents on how multiethnolectal they sound ("Screening Score"). In the present contribution, we analyze the transcripts of a picture description task, focusing on lexical and phonetic innovations with respect to traditional Zurich German. We assume that adolescents who are perceived as speaking rather multiethnolectal Zurich German show more Standard German interferences both on the lexical and the phonetic level. Indeed, the Screening Score is a statistically significant predictor for the number of interferences. In addition, the probability of purely phonetic interferences as opposed to lexical interferences increases with higher Screening Scores.