I haven’t had a “quacking” sensation with speech, but I’ve experienced speech that sounds somehow clipped. This event would typically occur when the barometric pressure changes. It’s nowhere’s near as noticeable with my aids in, but before I got the aids (at age 30-odd), it was really unbearable, making it difficult to comprehend speech.
So my advice is twofold: 1.) see if there is a “trigger” event causing this sensation (weather change, flying at altitude, food allergy, medication being taken, etc.,) and 2.) get in to see your audiologist to see what frequency ranges can be adjusted to mitigate that affect.
While I have a fairly FLATLINED audiogram, I tend to want the lower frequencies of speech boosted with a bit of high frequency turned down so the ambient sounds aren’t “shattering” in their sharpness. Hope that helps!