(a) This Code section shall apply to all counties of this state which according to the United States decennial census of 1970 or any future such census have a population of 150,000 or more.

(b) In any county of this state referred to in subsection (a) of this Code section, a stenographer is authorized to be present and in attendance upon the grand jury while any witness is being examined by the grand jury. Before attending the grand jury, the stenographer shall take the following oath:

"I do solemnly swear that I will keep secret all things and matters coming to my knowledge while in attendance upon the grand jury, so help me God."

(c) The district attorney of the circuit in which the county is located shall appoint the stenographer and fix the compensation therefor, such compensation to be paid by the county.

(d) The stenographer is authorized to take and transcribe the testimony or any part of the testimony of any witness who testifies before the grand jury and to furnish the transcript of testimony to the grand jury or the district attorney. The stenographer shall be incompetent to testify at any hearing or trial concerning any matter or thing coming to the knowledge of the stenographer while in attendance upon the grand jury.

(e) In any county of this state having a population of 200,000 or more according to the United States decennial census of 1970 or any future such census, a recording device may be used in lieu of the stenographer provided for in subsection (a) of this Code section. Any person transcribing testimony from such recording shall be incompetent to testify at any hearing or trial concerning any matter or thing coming to the knowledge of the person from the recordings.