The second of Hayne's stages of acquisition is early production, during which learners are able to speak in short phrases of one or two words. They can also memorize chunks of language, although they may make mistakes when using them. Learners typically have both an active and receptive vocabulary of around 1000 words. This stage normally lasts for around six months.
The third stage is speech emergence. Learners' vocabularies increase to around 3000 words during this stage, and they can communicate using simple questions and phrases. They may often make grammatical errors. The stage after speech emergence is intermediate fluency. At this stage, learners have a vocabulary of around 6000 words, and can use more complicated sentence structures. They are also able to share their thoughts and opinions. Learners may make frequent errors with more complicated sentence structures. The final stage is advanced fluency, which is typically reached somewhere between five and ten years of learning the language. Learners at this stage can function at a level close to native speakers.
The time taken to reach a high level of proficiency can vary depending on the language learned. In the case of native English speakers, some estimates were provided by the Foreign Service Institute (FSI) of the U.S. Department of State, which compiled approximate learning expectations for a number of languages for their professional staff (native English speakers who generally already know other languages). Of the 63 languages analyzed, the five most difficult languages to reach proficiency in speaking and reading, requiring 88 weeks (2200 class hours), are Arabic, Cantonese, Mandarin, Japanese and Korean.