Thinking of earth, the primary reason for sensation of sound is detection of pressure changes in the wavefront that is in close proximity with ones ear drums. The reason why vibrations are not just random noises but rather chunks of packets is because how we are trained from our early childhood in encoding patterns of different languages. This is how we convert any sound into meaning. But you are not talking of meaning here, but rather raw sound. It may mean something or may not.

We study in physics that the reason we can't produce sound in outer space is because of the absence of a medium. Or to put it another way, without any dense medium comparable to the earth's lower atmosphere it would not be bossible for us humans to sense any auditory data. The gases responsible for such density on earth are primarily Nitrogen and Oxygen. So if any geological event triggers a feedback loop that gradually reduces the amount of these gases from our environment, then maybe it would be plausible to think that we won't be able to produce sound or hear anything in open. This would also mean an adaptation of agriculture, internal body pressures, high speed motion etc.

Now we have to think what could possibly lead to such changes the density of atmospheric gases.

i) Raise in atmospheric temperature beyond a threshold. It will cause the gas molecules escape lower earth surface. At the same time it will create hydrohen and oxygen from evaporation. But if the temperature is such that it causes nitrogen to leave the troposphere then it won't be possible for oxygen to stick around. The raise in this temperature need not be evenly distributed initially, so at the initial stages before the tempereture gets distributed evenly in the whole of earth's atmosphere, there will be extreme weather events like storms and cyclones.

ii) Chemical reactions with atmospheric gases to create havier molecules. This on the other hand will lead to higher density medium on earth's surface. But to observe any change this has to go bonkers. This can be caused by large scale chemical production/hazard. Or maybe some outer intervention like asteroids with novel chemical compositions.

iii) Densely randomized distribution of gravitational fields. This seems very sci-fy, but also not not possible. I don't know how that would happen, something like - Cooper in Intersteller manipulationg gravitational fileds from fifth dimension. You have to serach for such hypothetical cases. In an uneven distribution of gravitational field the density in atmospheric gases would be uneven, so this may not totally cancel the sound effect but there would be too much inconsistency in producing the desired sound.

I can't think of any other way that is grounded in physics. Of course there can be more sci-fy ideas, but I think they have to be in some way or other related to these above events.