My natural speaking volume is on the louder end of the spectrum. In in-person conversations visual cues, even just seeing the other people, help me to regulate it, though I can still mess up when I'm not paying enough attention. (Lifelong struggle here.) And on a phone call with one other person I can match my volume to what I hear, and use the volume control on the speaker to set that at a good volume. My problem is with group conference calls.
I was just in a call with two other people where one was much quieter than the other (a not-uncommon problem). My speakers only have one volume setting, so for to hear the one at all the other was loud. I didn't realize until afterwards, but I was matching the loud person's volume, which meant I was bothering a coworker who sits near the conference room. Because the other people didn't have video, I couldn't make use of visual cues and the quiet person never said "hey, could you tone it down?" to either of us.
What techniques can I use to keep my own speaking volume at a reasonable level regardless of the variations in volumes among other speakers on a call? I'd like to prevent the problem, not apologize to coworkers for it later.
I'm aware of this question, but I think the phone aspect (and attendant lack of visual cues) is an important difference. Also, before you ask, my hearing's fine.