Is it legal for an employer to tape employees conversations in the work place.

No, in NY that is a criminal offense and should be reported to the police. Video recording is legal, even in secret, but not secret voice recording.

Taping employee audio (without consent of at least one in the conversation) would usually violate section 250.05 of the NY Penal Law. That's why I always advised employers to use surveillance cameras that videotaped what could be seen but not heard (i.e. no mic on the camera).
But...please be sure you did not give consent to this when you signed a thousand documents on your first day of work in HR.

Audio recordings of employees are usually not allowed in New York State.

This answer does not constitute legal advice and you should contact an attorney to confirm or research further any statements made in this answer. Any statements of fact or law I have made in this answer pertain solely to New York State and should not be relied upon in any way in any other jurisdiction.