There are definitely "deficits", i.e. sounds that we never learn to produce or distinguish because they aren't used by any of the languages we speak. In fact, w

There are definitely "deficits", i.e. sounds that we never learn to produce or distinguish because they aren't used by any of the languages we speak. In fact, we all have a lot of deficits: "Linguists estimate that the world’s languages use 800-plus phonemes [basic sounds]. Any given language will use only a subset of these, typically a few dozen."[1] Examples that might be familiar to an English speaker include the French "u" sound and nasal vowels, which are clear to a French person but difficult for an English speaker to distinguish, or the tones in Chinese language (which I still can't distinguish well despite studying Chinese). And these deficits definitely contribute to the strange foreign accents we develop when learning new languages. But an accent is not innately tied to those deficits. Hugh Laurie learned a very good American accent without losing his English accent. I even picked up the ability to speak with a bit of British accent when I lived in Europe, but still normally spoke with my American accent. 1: https://www.csmonitor.com/The-Culture/Verbal-Energy/2016/0128/The-800-phonemes-of-the-tiniest-linguists https://www.csmonitor.com/The-Culture/Verbal-Energy/2016/012...