Abstracts Submitted: 250
Number of Users: 295
View Abstracts Submitted
Back to home Page
Nowadays, in room acoustic assessment, impulse response is usually obtained using MLS or Swept-Sine signals. Despite their many advantages, in preliminary and orientation studies, simplified methods of creating an input signal that allow to evaluate the acoustic condition of a given room are still used. Due to the lack of information on the full acoustical characteristics of these sources, the results obtained that way should be treated only as informative. Commonly available literature describes number of results of similar research about non-standard sources, nevertheless the attempt to classify them on their characteristic features has a significant cognitive value. In the paper, research of impulse responses and acoustical parameters determined on them were made on the basis of measurements carried out in one of auditory rooms at AGH University of Science and Technology in Cracow. The measurements were made with accordance with the ISO 3382-2:2008 (Acoustics - Measurement of room acoustic parameters - Part 2: Reverberation time in ordinary rooms). Sound signals were recorded using a measuring system equipped with a class 1 free-field microphone, G.R.A.S. 46AE, and then analyzed using Dirac software. Five types of sound sources were selected for the analysis: hand claps, explosions of balloons with various shapes, a plastic bag, a paper bag, and a plank hitting the floor. Inflated balloons were punctured with a pin at the center (from above/from the side), bags were struck with an open hand. Clapping and hitting with a board were done in a repeatable way. For the purpose of comparison, acoustical parameters of the same room were also obtained by using Bruel & Kjaer commercial measuring equipment. The analytical part of the paper focuses on the differences in parameter values: three methods of decay curve evaluation – early decay time, EDT, T20, T30, and other parameters: impulse-to-noise ratio, INR, bass ratio, BR(RT), treble ratio, TR(RT), central time, TC, speech and music clarity indicator, respectively C50 and C80, definition D50 and four parameters describing speech transmission in a room: STI (female), STI (male), STIPA (female), STIPA (male). In addition, the reverberation time values obtained from the measurements were also referred to the theoretical values determined according to the Sabine and Eyring formulas. Differences in parameter values for particular frequency bands allowed the authors to classify examined sound sources due to their suitability to the purpose as well as scope of the research. The result of the research and classification will be the increase of knowledge in the selection of the input signal source for specific applications. Choosing the best source or combination of sources will provide better results in preliminary research of room acoustics or their subjective evaluation.
© Copyright 2017 All Rights Reserved