Any elected or designated representative of a voluntary association in the industry whose members have an economic interest in any matters covered by Act No. 254 of the Public Acts of 1933, as amended, being sections 475.1 to 479.49 of the Compiled Laws of 1948, shall have the right to appear and be fully heard and fully participate as a party of interest on behalf of his association only in any public hearing conducted by the public service commission relating to matters covered by Act No. 254 of the Public Acts of 1933, as amended, being sections 475.1 to 479.49 of the Compiled Laws of 1948. The same privilege shall be extended to an industrial representative; this section shall not be construed to affect in any way section 7 of this act as added by Act No. 89 of the Public Acts of 1967.