The gel pad at the link below will work with the Peltor Tactical 6/Sound Trap Tactical 6S Hearing Protectors. Please email us for more information.
https://www.opticsplanet.com/peltor-aviation-parts-ac-camelback-gel-sealing-rings-hy80.html
One of the keys to getting the best sounding voice communication will be having the best NRR rating, as well as the environment you're trying to communicate in. With any hearing protection that allow face-to-face conversation, voice will still be muted if your surroundings are loud enough for the hearing protection to be cutting it out.
Here is a video that will help you with that process: https://www.youtube.com/watch?v=rV0VoekV7yc