Accession Number:

ADA399241

Title:

A High Intensity Infrasonic Acoustic Test System

Descriptive Note:

Corporate Author:

ARMY RESEARCH LAB ADELPHI MD

Personal Author(s):

• Boesch, H. E., Jr.
• Reiff, Christian G.
• Benwell, Bruce T.

Report Date:

2001-11-01

Pagination or Media Count:

64.0

Abstract:

We describe the design, mathematical modeling, construction, and test of an acoustic test system intended to support the performance of high-intensity acoustic effects experiments on large targets at low-sonic to infrasonic frequencies. An early experimental version of the system, HILF1, used a compressed-air source and airflow modulator from the ARL Mobile Acoustic Source MOAS and a single-volume Helmholtz resonator test chamber to achieve sound pressure levels SPL above 140 dB in a 5-cu m volume. Based on results from this system, a more advanced system, HILF2, was designed and built. HILF2 uses a compressed-air source based on automotive superchargers, a low-impedance airflow modulator, and a two-volume Helmholtz resonator test chamber to achieve sustained high-purity sinusoidal sound pressure levels in excess of 155 dB in a 2.5-cu m test volume at frequencies from 2 to 20 Hz.

Descriptors:

• *ACOUSTIC EQUIPMENT
• *INFRASONIC RADIATION
• MATHEMATICAL MODELS
• FREQUENCY
• AIR FLOW
• INTENSITY
• TEST EQUIPMENT
• TARGETS
• MOBILE
• LOW LEVEL
• LEVEL(QUANTITY)
• IMPEDANCE
• SOUND PRESSURE
• MODULATORS
• AUTOMOTIVE COMPONENTS
• COMPRESSED AIR
• NOISE(SOUND)
• SUPERCHARGERS

Subject Categories:

• Acoustics
• Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE