  Since the foundational work of William Labov on the social stratification of
language (Labov, 1964), linguistics has made concentrated efforts to explore
the links between sociodemographic characteristics and language production and
perception. But while there is strong evidence for socio-demographic
characteristics in language, they are infrequently used in Natural Language
Processing (NLP). Age and gender are somewhat well represented, but Labov's
original target, socioeconomic status, is noticeably absent. And yet it
matters. We show empirically that NLP disadvantages less-privileged
socioeconomic groups. We annotate a corpus of 95K utterances from movies with
social class, ethnicity and geographical language variety and measure the
performance of NLP systems on three tasks: language modelling, automatic speech
recognition, and grammar error correction. We find significant performance
disparities that can be attributed to socioeconomic status as well as ethnicity
and geographical differences. With NLP technologies becoming ever more
ubiquitous and quotidian, they must accommodate all language varieties to avoid
disadvantaging already marginalised groups. We argue for the inclusion of
socioeconomic class in future language technologies.
