Voice quality is an important dimension in human communication, used to mark a variety of phenomena in speech, including prosodic prominence. Even though numerous studies have shown that speakers modify their voice quality parameters for marking prosodic prominence, the impact of these modifications on perceived prominence is less studied. Our investigation looks at the effect of a well-known measure of voice quality, cepstral peak prominence (CPP), on syllabic prominence ratings given by both naive and expert listeners. Employing read speech materials in German, we quantify the role of CPP alone and in combination with other acoustic cues marking prominence, namely intensity, duration and fundamental frequency. While CPP, by itself, had a significant effect on the perceived prominence for most of the listeners, when used in conjunction with the other cues, its impact was reduced. Moreover, when assessing the importance of each of these four cues for determining the perceived prominence score we found important individual variation, as well as differences between naive and expert listeners.