I am not sure why people are so against this. People listen to and are persuaded just by the voice of a person all the time, it is called the radio and the telephone. If the chair is talking to you, the person would think magic if the speaking were visible like it grew a mouth, or if it was just audio coming from the chair it could be a concealed speaker or whatever.
But if the person is persuasive they are persuasive, whether it is done in person or just through their voice. As long as you are not trying to pass yourself off as a sentient teapot and there is a reasonable reason your voice is coming from that spot you should be able to use your social skills just fine.