2019 Premiere Elements timestretch loss of audio bass

I recently started using 2019 Premier Elements to edit videos for dance instruction.  Editing video and audio has worked well, with one exception. When attempting to slow a video to 80 - 90% utilizing timestretch the resulting video and audio are slowed as desired, but the audio exhibits a significant loss of bass, which is critical for dance beat synchronization. The timestretch *maintain pitch* option did not restore the bass loss, and searching the FAQs and INet returned no results. Is there an explanation, option, configuration or process that would address this problem?  Thanks in advance for your assistance!