Speech Pathologists M.D.
Most speech pathology issue arise when we are young, as children we tend to skip a sound or two, mispronounce certain letters like "L" or swallow the endings of the words. A trained doctor often works with us a that still young age. However, when learning a new language some sounds that we lack didn't exist in our Native tongue, therefore bringing this issue to adulthood.
Accent Coach and Dialect Development professionals work mostly with career oriented goals. Some career require to sound as a "local" or "native" rather than having a perfect grammar.
This mostly applies to actors, journalists, musicians and singers. Usually when working with a student the goal isn't to clean the accent, but the target multiple at once.
Native Speaker Practice
While learning a language from a different language group, many people forget that sounds (like words) do not align and therefore sound wrong, which may be hard to understand to others.
Practicing with a native speaker helps you hear and sound better, clearer.
The correct pronunciation makes you feel confident and fluent and is considered one of the last steps to fluency.