30.—(1) The provisions of section 110(2) (review of assessment in case of unforeseen aggravation) shall not apply to an assessment of the extent of disablement in respect of occupational deafness until after the expiration of 5 years from the date of commencement of the period taken into account by that assessment.
(2) The provisions of section 110(2) shall not apply to an assessment of the extent of disablement in respect of occupational deafness which is less than 20 per cent.
31. Subject to the provisions of regulation 30 and notwithstanding the provisions of section 110(5) (leave of medical appeal tribunal required to review assessment in certain cases), a life assessment in respect of occupational deafness made by a medical board or a medical appeal tribunal shall not be reviewed in accordance with section 110(2) (review of assessment in case of unforeseen aggravation) without leave of a medical appeal tribunal, and in the case of a provisional assessment in respect of occupational deafness no such leave shall be required.