What phonetic phenomenon involves sounds becoming similar to nearby sounds?

The correct answer is assimilation. This phonetic phenomenon occurs when a sound becomes more like a neighboring sound, resulting in a change that can facilitate easier articulation or increase the fluidity of speech. Assimilation can occur in various forms, such as progressive or regressive, where a sound affects a following or preceding sound, respectively.

For example, in English, the word "input" is often pronounced more like "imput" in casual speech, where the /n/ sound changes to /m/ because of the following bilabial /p/ sound. This adjustment makes the transition between the sounds smoother.

Understanding assimilation is crucial for analyzing speech patterns and pronunciation variations across different contexts and dialects. This phonetic process not only reflects natural speech tendencies but also illustrates how phonemes interact in spoken language.