Government_Minimum_Requirements.pdf

1.0 GENERAL DESCRIPTION

This specification covers the salient design and performance requirements for one (1) hemi-anechoic acoustic chamber to be used for providing an acoustically isolated test environment. Capabilities must provide ambient acoustic noise reduction within a limited space allotment as detailed below.

2.0 CHAMBER SPECIFICATIONS

2.1 Chamber Exterior

The exterior of the chamber shall fit within the following parameters:

• Width: 17’9” (+0%/-10%)

• Height: 14’11” (+0%/-10%)

• Depth: 17’3” (+0%-10%)

2.2 Chamber Interior

2.2.1 The minimum interior workspace dimensions shall be:

• Width: 13'4"

• Height: 12'0"

• Depth: 14'8"

2.2.2 Accessories

2.2.2.1 One (1) panel, 24” x 24” or larger, to allow for the pass-through of cable connectors with a diameter of 5”. Pass-through panel shall be located on the left side of the chamber when looking at the door from the outside.

2.2.2.2 Minimum of six (6) internal low profile light fixtures with an external switch.

2.2.2.3 One (1) panel, 6” x 12” or larger, to allow for the pass-through of four (4) water hoses access to cooling water. Alternatively, a quantity of eight(8) threaded ¾” hose connections, four (4) on the inside and four (4) on the outside of the chamber, allowing for water to pass through. Pass-through panel (or hose connections) shall be located on the left side of the chamber when looking at the door from the outside.

2.2.2.4 A total of six (6) noise level meter mounting mechanisms that allow for height adjustment. Mounting mechanisms shall be affixed roughly in the center of each surface.

Mounting mechanisms shall be placed as follows: one (1) on each wall not containing a door for a total of three (3); one (1) on the door; and at least one (1) on the ceiling.

2.3 Ventilation

The chamber shall be ventilated to allow for passive air exchange such that the chamber does not exceed an average of 10 degree temperature increase in one (1) hour with a 4 kilowatt heat load.

2.4 Door

2.4.1 One (1) manually operated door, with opening bar or knob.

2.4.2 The chamber door shall be hinged on the right hand side of the exterior, opening outward from the chamber.

2.4.3 The chamber door shall be equipped with acoustic wedges or panels to support the acoustic performance requirements of the chamber as specified in SOW paragraph 3.1.

2.4.4 The chamber door shall be a minimum of 7’ wide and a maximum of 8’ wide x 8’ tall.

2.4.5 The chamber door shall be placed in the 17’9” side of the chamber

3.0 PERFORMANCE

3.1 Acoustic Noise Reduction

The chamber shall provide a minimum ambient noise reduction in accordance with the table below.

For purposes of this equipment specification, noise reduction is defined as the reduction in ambient airborne noise outside the semi-anechoic chamber relative to airborne noise within the semi-anechoic chamber. The frequency provided is the octave band center frequency in Hertz (Hz). The Decibel (dB) noise reduction is relative to a sound pressure level of 20 micro Pascals (µPa).

Frequency (Hz) 63 125 250 500 1000 2000 4000 8000 Noise Reduction (dB) -Threshold 10 20 20 20 20 20 20 20 Noise Reduction (dB) - Goal 15 25 25 25 25 25 25 25

3.2 Cut off Frequency

The hemi-anechoic chamber cut-off frequency shall be equal to or less than 250Hz.

4.0 PRE-SHIPMENT TESTING

The contractor shall test the chamber for operation and conformance in accordance with the purchase specifications prior to shipment. Results of the Pre-Shipment Testing shall be delivered in accordance with

CDRL A001.

5.0 ON-SITE ASSEMBLY

The contractor shall conduct on-site assembly of the equipment at the Naval Undersea Warfare Center Division, Newport RI. Upon on-site assembly, the contractor shall test the chamber for operation and conformance in accordance with the purchase specifications. A report on the results of the On-Site Assembly Testing performed shall be delivered in accordance with CDRL A001.

NOTE: The high-bay door is 10’ wide by 12.5’ tall. All items needed for on-site assembly must fit through this door.

6.0 DOCUMENTATION

The contractor shall provide a complete set of commercially available chamber documentation consisting of Operation Manuals, Drawings, Wiring Diagram, and Parts Lists, in accordance with CDRL A002.