A professional office or studio of a lawyer, architect, real-estate broker, doctor, dentist, artist, engineer, musician or teacher, or member of a similar established profession (but not including an office or establishment of a veterinarian, mortician, undertaker or embalmer) residing on the premises, and including a small professional plate or sign not exceeding one square foot in area as the only display of advertising, provided that:
(a) Not more than 10% of the area of the ground floor of such residence shall be so used.
(b) Not more than one assistant shall be employed in any such professional office or studio.
(c) If instruction in vocal or instrumental music or dancing is given, such studio shall be equipped and used so that sounds therefrom shall not be heard in nearby premises.
(d) Two parking units shall be provided in the rear yard of the premises.