§ 9-605. Sound level reduction (SLR) design requirements.

(a)

General requirements. The SLR requirements found in section 9-604 may be achieved by any suitable combination of building design, choice of building materials and execution of construction details in accordance with established architectural and acoustical principles. The SLR requirements shall apply to all occupied rooms having one (1) or more exterior walls or ceilings, when furnished in accordance with the intended final usage of the room.

No new building or structure for which an SLR of 25, 30, or 35 is required by section 9-604 may be constructed unless and until a building permit therefore has been issued by the county. No such permit shall be issued unless and until conformance with the requirements of section 9-604 is indicated by plans and specifications for the building or structure.

Prior to granting a certificate of occupancy/completion, one (1) of the following must be completed (at the expense of the builder/owner):

(1)

A filed test by a qualified consultant to verify the SLR of the building; or

(2)

A certification of design criteria by a qualifiedacoustical consultant that verifies the SLR of the building.

(b)

Verification testing procedure/SLR design information. Sound level reductions shall be determined for at least four (4) aircraft fly-over events by a typical air carrier-sized jet aircraft for each room tested. The resulting value assigned to the room shall be the average value of the individual fly-over events. Using the noise signal generated by an individual aircraft fly-over event, outside and inside noise levels may be measured simultaneously. The noise levels measured outside and inside the room may be observed directly by simultaneously reading the maximum noise levels on two (2) sound level meters; or the outside and inside fly-over event may be recorded on magnetic tape, and the required noise level reduction determined by the analysis of the recorded signals. In either case, the two (2) measuring systems used for outside and inside noise measurement must satisfy the requirements for a type 11 sound level meter according to ANSIU S1.4-197. The two (2) systems shall be calibrated prior to and following the fly-over events so that they indicate the same level within one (1) decibel for the same noise, using suitable calibration procedures as specified by the manufacturer. For calculations undertaken for purposes of meeting the requirements assumed outside spectrum shown in Figure 2 [incorporated herein by reference only].

(Ord. No. 2000-07, § 2, 3-21-00; Ord. No. 2001-26, § 1.O., 12-18-01)