Auditory Progress Bars (APB) were originally intended to augment Visual Progress Bars (VPB) to create multimodal displays. More recently, APBs have been tested in absence of VPBs for use in the on-hold telephone setting. In this setting, APBs are a viable option for communicating the probable time remaining in the on-hold wait. However, past studies measure the effectiveness of APBs retrospectively, which is appropriate for understanding how accurately callers can judge how long they have been waiting on hold, but is not appropriate for determining if APBs are intuitively communicating the probable time remaining in the wait-which is more relevant to the caller's needs. Here, we measure the effectiveness of 3 distinct APBs prospectively which is more consistent with the caller's concern of how much longer the wait will be before their call is answered. Furthermore, we make APBs more similar to VPBs by playing the APB's endpoint before the APB's beginning point. We found evidence that the accuracy of prospective estimations is a product of APB design, and that the awareness of the endpoint has no affect on the accuracy of prospective estimations.