Listening comprehension and vocabulary knowledge are closely intertwined. Vocabulary knowledge (size) has been found to be a strong predictor of successful listening comprehension even when listening is done under adverse conditions. Previous research has focused on advanced proficiency, or native level listeners. This study aims to fill a research gap by studying the improvements to listening comprehension in speech-shaped noise of ten intermediate level French as foreign language learners enrolled at French courses at an American university. This study focuses on whether a 4-hour instruction on diplomatic French vocabulary terms, using a background speech-shaped noise presented at a +5dB signal-to-noise ratio would increase the comprehensibility of unfamiliar accented speech, from nine different speakers in intermediate level learners of French as a foreign language. The results show that intermediate level listeners improved their listening comprehension skills, and that vocabulary training was the most important factor. Findings also show that intermediate-level listeners can adapt to unfamiliar accented speech, and that the listeners can be taught advanced-level vocabulary when it is presented as language for specific purposes and under adverse listening conditions.