This variationist sociotonetic study is the first to use free-speech data for exploring tone. Due to the challenges of analyzing tone in free-speech data, prior work on sociotonetics has been limited to relatively formal speech styles: word lists, sentence frames, and phrase lists. But connected speech styles, including free speech and reading passages, are important for segmental sociophonetics and most other linguistic variables. Using field data from the Sui language of China, this paper develops a practical approach for analyzing tone variation in connected speech data, and then applies it to a specific research question about dialect contact in exogamous Sui villages. Results show that some types of intra- and inter-speaker tone variation in connected speech can be effectively analyzed, although other types of tone variables are neutralized in this speech style.