"Can someone who earned a doctorate degree in Field X be referred to as 'doctor'"
I have seen this question all over the internet and on forums. People have all kinds of ideas about this; some of them are spot-on, some are arrogant and ill-informed. The answer to this question isn't that complicated.
If you've earned a doctorate degree, whether that is a MD/DO, PhD (in any field), CScD, EdD, DPT, DC, JD, DDS, AuD, DD, PharmD, PsyD, SLPD, OTD, DNP, ClinSciD, etc., you have earned the right to be referred to as 'Dr. Bennifer Honeypants' (or whatever your name is); if you finished a doctoral degree from a regionally accredited university (this is for the U.S.; not sure how accreditation at universities works in other countries) , you can legitimately and honestly carry the title 'Dr.'
The problem is not with the title 'Dr'...the problem is with people using it inappropriately and/or to mislead. It is unethical for a DPT or AuD(or any non-MD/DO doctor) to enter a patient's hospital room and pretend to be a physician. This works the other way, however; it just as unethical for a MD/DO to enter a physical rehabilitation clinic and let patients believe they are a DPT, or for an MD/DO to enter the physics department at a university and pretend to be a professor of physics.
If an employee at a hospital, with an earned doctorate that is related to the field in which they are working at that hospital, enters a patient's room it is ethical to clarify what field at that hospital they work in (which serves to let the patient know their area of expertise). For instance, the speech-language pathologist with a clinical doctoral degree (SLPD or CScD) at a hospital should introduce themselves to the patient like so: "Hello, I'm Dr. Bennifer Honeypants. I'm your speech-language pathologist today." The DPT with a clinical doctoral degree at a hospital should introduce themselves to the patient like so: "Hello, I'm Dr. Bennifer Honeypants. I'm your physical therapist today." If there is any indication that the patient thinks you are a medical doctor (either through asking you outright or through asking questions that are outside you area of expertise), it is that person's duty to tell the patient, "That's a good question. However, I am not a medical doctor. That would be a great question to ask her/him when you see her/him."). This action absolutely applies to MDs/DOs as well; when seeing a patient at a hospital, the MD/DO should introduce themselves to the patient like so: "Hello, I'm Dr. Bennifer Honeypants. I am your physician today," or "Hello, I'm Dr. Bennifer Honeypants. I am your oncologist." Likewise, if a MD/DO is giving a lecture in a biology department to a class full of PhD candidates, they should tell the room, "Hello. I'm Dr. Honeypants. I am a medical doctor." If you have earned a legitimate doctorate degree from a legitimate university and are on an airplane and someone starts having seizures, and the person next to them shouts out, "Is anyone here a doctor?", you are acting beyond unethically if you rush over and say "I'm a doctor!" when your doctorate degree is a PharmD, SLPD, DPT, etc. and not an MD/DO.
See how easy that is? It seems that most of the arguments about who can and cannot call themselves Doctor on forums and editorials online and elsewhere are nothing more than d*ck measuring contests. If you earned a doctorate from a legitimate university, you have earned the right to be referred to as 'Doctor', but it is YOUR ETHICAL RESPONSIBILITY to not misrepresent yourself to others by clarifying exactly what type of doctor you are.
