ASTM E2611-24 PDF

Full title and description

Standard Test Method for Normal Incidence Determination of Porous Material Acoustical Properties Based on the Transfer Matrix Method. This ASTM standard specifies a laboratory procedure that uses an impedance/transmission tube, four microphones, and digital frequency analysis to determine normal-incidence transmission loss and other acoustical properties of porous and fibrous materials by deriving the acoustic transfer matrix.

Abstract

This test method defines the four-microphone transfer-matrix technique for measuring normal-incidence acoustic properties (including transmission loss and related parameters) of porous materials using an impedance/transmission tube and a digital analyzer. The standard is written in SI units and includes requirements for instrumentation, measurement procedure, and data reduction used to derive the acoustic transfer matrix. It replaces the previous edition ASTM E2611-19.

General information

• Status: Active standard.
• Publication date: 1 May 2024 (designation E2611-24).
• Publisher: ASTM International.
• ICS / categories: 17.140.01 (Acoustic measurements and noise abatement).
• Edition / version: E2611-24 (revises ASTM E2611-19).
• Number of pages: 14 pages.

Scope

This standard covers the use of an impedance/transmission tube fitted with four microphones and a digital frequency analysis system to measure normal-incidence transmission loss and to derive the transfer matrix of porous materials. It addresses instrumentation, microphone placement, sample mounting, measurement sequence, data acquisition and reduction, and reporting. SI units are designated as the standard units for results. The standard does not attempt to address all safety concerns related to test setup and operation.

Key topics and requirements

• Four‑microphone transfer-matrix measurement technique (impedance/transmission tube based).
• Determination of normal-incidence transmission loss, acoustic transfer matrix, and derived acoustical properties for porous materials.
• Required equipment: impedance/transmission tube, four pressure-microphones, calibrated data-acquisition/digital frequency analysis system, sample holders and seals.
• Calibration, microphone location and phase/level matching, and verification checks to control measurement uncertainty.
• Data reduction procedures to compute transfer matrix elements and transmission loss; results reported in SI units.
• Comparative relationship with two‑microphone impedance-tube methods and international equivalents (see Related standards).

Typical use and users

Used by acoustical test laboratories, materials and acoustic-absorber manufacturers, research institutions, consultants in building and environmental acoustics, and quality-control departments for product development, specification compliance, and comparative performance testing of porous and fibrous acoustic materials. The method is applied where small-sample, normal-incidence transmission and impedance properties are required.

Related standards

Key related standards and practices include the previous edition ASTM E2611-19 (superseded), ASTM E1050 (two-microphone impedance tube method for absorption and impedance), and international standards such as ISO 10534-2 (impedance-tube two-microphone technique). These documents describe complementary impedance-tube techniques for absorption, impedance and related properties; laboratories commonly use them together to fully characterize acoustic materials.

Keywords

4‑microphone, impedance tube, transmission tube, transfer-matrix method, transfer function, normal incidence, transmission loss, porous materials, acoustic impedance, SI units.

FAQ

Q: What is this standard?

A: ASTM E2611-24 is a laboratory test method that specifies the four-microphone transfer-matrix technique for measuring normal-incidence acoustic properties (notably transmission loss) of porous materials using an impedance/transmission tube and digital analysis.

Q: What does it cover?

A: It covers required equipment, microphone locations, calibration and verification procedures, the measurement sequence, data reduction to obtain transfer-matrix elements and transmission loss, and reporting conventions (SI units). It is focused on normal-incidence measurements in a tube environment and does not replace reverberation-room random-incidence methods.

Q: Who typically uses it?

A: Accredited acoustical testing laboratories, manufacturer R&D and QA teams for absorptive and transmissive materials, independent acoustical consultants, and academic researchers performing small-sample normal-incidence acoustic characterization.

Q: Is it current or superseded?

A: E2611-24 is the current (2024) edition and supersedes ASTM E2611-19. The document is listed as active and was published/approved in 2024.

Q: Is it part of a series?

A: It is part of the family of impedance-tube test methods maintained by ASTM and complements two-microphone impedance-tube methods (e.g., ASTM E1050) and corresponding ISO impedance-tube standards (ISO 10534-2). These related standards together provide a suite of methods for normal-incidence absorption, impedance and transmission measurements.

Q: What are the key keywords?

A: 4‑microphone, transfer matrix, impedance tube, transmission loss, normal incidence, porous material acoustics, transfer function.