allophone

This term describes the subtle, physical differences in how we pronounce a sound depending on its position in a word. It focuses on the actual sound produced by the mouth rather than the mental category of the sound. For instance, the p sound at the start of a word often feels like a puff of air, while the p at the end of a word does not, yet the brain treats them as the same letter. In a linguistic context, allophones are essentially the different costumes a single sound wears. They are predictable and automatic, meaning a native speaker usually does not realize they are making these distinctions until they are pointed out by a phonetician.