Auditory progress bars (APBs) are aural stimuli designed to convey time progression. To investigate the relationship of APBs and workload ratings during a telephone holding context, two APBs were tested alongside ethnographically-validated caller secondary behaviors in a multitasking procedure. Predictions based on Multiple Resources Theory were found to be absent or in the opposite direction, in that an electronic musical APB was rated higher than a voice-based APB in workload as measured by NASA-TLX and task performance. Differences between APBs were manifest through both overall workload ratings and NASA-TLX subcomponent scores. Results indicate that workload measurement can be noisy, particularly when task demands are low to moderate, and that the small effect of APB type may be less important than other considerations for APB design.