Comparative study of a proposed time varying loudness standard.

Abstract

While noise levels are most often quantified using physical quantities including A-weighted sound pressure level, these metrics do not adequately represent the human perception of the noise. For this, loudness is a more appropriate acoustic metric as it describes the perceived acoustic intensity of a sound. Given that real sounds are often unsteady, a most useful loudness calculation will also account for the perceptional phenomena of time and temporal masking. One such model is the DIN 45631-A1. However, this standard takes a less common approach in that it does not fully describe a methodology to calculate the unsteady loudness. It instead offers a more general procedure along which it provides open-ended checks and balances for verifying the progress through the various calculation steps. The caveat of this is that while conditions specified by this standard may be satisfied, it has been suggested that varying results may be achieved due to the procedure’s open architecture. Using several commercial software applications which purport to follow the DIN standard, this study investigated several of these commercial applications and compared the calculated results for several common time varying inputs to determine the extent to which compliance with DIN 45631-A1 results in identical loudness scores.

Sound Absorption Coefficient Analysis for Composite Made of Agricultural Waste

“…The impedance tube method requires a short test time with a small sample size, therefore, this method is often used in research. The impedance tube used in this study is the Brüel & Kjaer impedance tube kit with a system consisting of a 4206-type impedance tube with two 4187-type ¼ inch condenser microphones, a 2716C amplifier, and a Xi LAN acquisition module type 3160-A-042, and connected to PC hardware via PULSE LabShop software version 1.16.0 [18]. The basic principle of this method is that in the impedance tube, a sound source (speaker) is installed at one end of the impedance tube, and the sample material is placed at the other end.…”