Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
speak to, speak with (vv.)
In most uses these combinations are interchangeable: I spoke to [with] her for only a few minutes. In some instances, however, there may be semantic distinctions: Speak to sounds a bit more one-sided, perhaps, than speak with, which may imply more give and take. And in one sense speak to suggests strongly that the speech is to be both one-sided and admonitory: I guess I must speak to him [about his behavior]. Talk works much the same way, except that you speak to [on the subject of] an issue far more often than you talk to an issue.
