Directivity Patterns for Room Acoustical Measurements and Simulations

Directivity Patterns for Room Acoustical Measurements and Simulations PDF Author: Martin Pollow
Publisher: Logos Verlag Berlin GmbH
ISBN: 3832540903
Category : Technology & Engineering
Languages : en
Pages : 192

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Book Description
The acoustics of rooms can be objectively described by the room impulse responses obtained for given transfer paths using measurement or simulation. In practice, the directionally dependent behavior of sources and receivers is often disregarded and thus assumed to be of omnidirectional type. In reality, however, these sources and receivers have specific directivity patterns, which are reported to induce audible differences. In this work a methodology to capture, analyze and process directivity patterns of sources and receivers is described. With the help of surrounding spherical microphone and loudspeaker arrays these directivity patterns are measured to be used in room acoustic applications. Room impulse responses with respect to specific directivity patterns can be realized using compact loudspeaker arrays with known directivity. Applying the results of directivity superposition to the set of measured room impulse responses, the acoustics for specific directivity patterns are found. Using a simulation of the room instead, source and receiver directivity patterns can be included in both wave based and particle based methods. The results of this work facilitate more authentic descriptions of room acoustics for specific source and receiver directivity patterns.

Directivity Patterns for Room Acoustical Measurements and Simulations

Directivity Patterns for Room Acoustical Measurements and Simulations PDF Author: Martin Pollow
Publisher: Logos Verlag Berlin GmbH
ISBN: 3832540903
Category : Technology & Engineering
Languages : en
Pages : 192

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Book Description
The acoustics of rooms can be objectively described by the room impulse responses obtained for given transfer paths using measurement or simulation. In practice, the directionally dependent behavior of sources and receivers is often disregarded and thus assumed to be of omnidirectional type. In reality, however, these sources and receivers have specific directivity patterns, which are reported to induce audible differences. In this work a methodology to capture, analyze and process directivity patterns of sources and receivers is described. With the help of surrounding spherical microphone and loudspeaker arrays these directivity patterns are measured to be used in room acoustic applications. Room impulse responses with respect to specific directivity patterns can be realized using compact loudspeaker arrays with known directivity. Applying the results of directivity superposition to the set of measured room impulse responses, the acoustics for specific directivity patterns are found. Using a simulation of the room instead, source and receiver directivity patterns can be included in both wave based and particle based methods. The results of this work facilitate more authentic descriptions of room acoustics for specific source and receiver directivity patterns.

Software-Based Acoustical Measurements

Software-Based Acoustical Measurements PDF Author: Federico Miyara
Publisher: Springer
ISBN: 3319558714
Category : Science
Languages : en
Pages : 438

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Book Description
This textbook provides a detailed introduction to the use of software in combination with simple and economical hardware (a sound level meter with calibrated AC output and a digital recording system) to obtain sophisticated measurements usually requiring expensive equipment. It emphasizes the use of free, open source, and multiplatform software. Many commercial acoustical measurement systems use software algorithms as an integral component; however the methods are not disclosed. This book enables the reader to develop useful algorithms and provides insight into the use of digital audio editing tools to document features in the signal. Topics covered include acoustical measurement principles, in-depth critical study of uncertainty applied to acoustical measurements, digital signal processing from the basics, and metrologically-oriented spectral and statistical analysis of signals. The student will gain a deep understanding of the use of software for measurement purposes; the ability to implement software-based measurement systems; familiarity with the hardware necessary to acquire and store signals; an appreciation for the key issue of long-term preservation of signals; and a full grasp of the often neglected issue of uncertainty in acoustical measurements. Pedagogical features include in-text worked-out examples, end-of-chapter problems, a glossary of metrology terms, and extensive appendices covering statistics, proofs, additional examples, file formats, and underlying theory.

Acoustical Measurements

Acoustical Measurements PDF Author: Leo Leroy Beranek
Publisher: Acoustical Society of Amer
ISBN:
Category : Science
Languages : en
Pages : 841

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Book Description


Modern Acoustical Techniques for the Measurement of Mechanical Properties

Modern Acoustical Techniques for the Measurement of Mechanical Properties PDF Author:
Publisher: Elsevier
ISBN: 0080531407
Category : Technology & Engineering
Languages : en
Pages : 457

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Book Description
This volume provides an overview of modern acoustical techniques for the measurement of mechanical properties. Chapters include Fundamentals of Elastic Constants; Point Source/Point Receiver Methods; Laser Controlled Surface Acoustic Waves; Quantitative Acoustical Microscopy of Solids; Resonant Ultrasound Spectroscopy; Elastic Properties and Thermodynamics; Sound Speed as a Thermodynamic Property of Fluids; Noninvasive Determination of Sound Speed in Liquids; Introduction to the Elastic Constants of Gases; and Acoustic Measurement in Gases.

Influences of external error sources on measurements of room acoustic parameters

Influences of external error sources on measurements of room acoustic parameters PDF Author: Martin Guski
Publisher: Logos Verlag Berlin GmbH
ISBN: 3832541462
Category : Computers
Languages : en
Pages : 176

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Book Description
Correct and precise measurements of room acoustic parameters are of fundamental importance for subjective room impression characterization and for the physical description of the sound field. This thesis investigates external influences on acoustic measurements and errors of the resulting room acoustic parameters. Theoretical models have been developed to predict these errors and indicate the tolerable limits of the described influences. To validate these models, specially designed room acoustic measurements that separate the individual influence factors have been conducted. Noise has been identified as one of the main influence factors and occurs during every measurement. In this thesis the performance of five commonly used stationary noise compensation methods are systematically analyzed depending on the peak signal-to-noise ratio. Impulsive noise that could also occur during the measurement is investigated separately, as the previously introduced compensation techniques are unsuited to handle the influence. The second part of this thesis analyzes the influence of time variances during measurements. Inter- and intra-measurement temperature changes, air movement, and human-sized scattering objects have been investigated.

Acoustical Evaluation of the NASA Lewis 9 by 15 Foot Low Speed Wind Tunnel

Acoustical Evaluation of the NASA Lewis 9 by 15 Foot Low Speed Wind Tunnel PDF Author: Milo D. Dahl
Publisher:
ISBN:
Category : Acoustical engineering
Languages : en
Pages : 68

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Book Description


Digital Signal Processing in Audio and Acoustical Engineering

Digital Signal Processing in Audio and Acoustical Engineering PDF Author: Francis F. Li
Publisher: CRC Press
ISBN: 146659389X
Category : Technology & Engineering
Languages : en
Pages : 228

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Book Description
Starting with essential maths, fundamentals of signals and systems, and classical concepts of DSP, this book presents, from an application-oriented perspective, modern concepts and methods of DSP including machine learning for audio acoustics and engineering. Content highlights include but are not limited to room acoustic parameter measurements, filter design, codecs, machine learning for audio pattern recognition and machine audition, spatial audio, array technologies and hearing aids. Some research outcomes are fed into book as worked examples. As a research informed text, the book attempts to present DSP and machine learning from a new and more relevant angle to acousticians and audio engineers. Some MATLABĀ® codes or frameworks of algorithms are given as downloads available on the CRC Press website. Suggested exploration and mini project ideas are given for "proof of concept" type of exercises and directions for further study and investigation. The book is intended for researchers, professionals, and senior year students in the field of audio acoustics.

Improved Acoustical Treatment for Engine Test Stands

Improved Acoustical Treatment for Engine Test Stands PDF Author: John T. Welbourn
Publisher:
ISBN:
Category : Absorption of sound
Languages : en
Pages : 104

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Book Description
This report summarizes an investigation and test of improved materials, noise control devices, and methods of application to engine test stands for the purpose ocing radiated noise and in creasing structural durability. Included are excerpts from an acoustical survey of a modified test stand and a full report of the acoustical evaluation of experimental exhaust units for a Transportable Turbojet Engine Test Stand. Exper imental work was performed at Wright-Patterson Air Force Base, Ohio. (Author).

Acoustical Materials

Acoustical Materials PDF Author: Pranab Saha
Publisher: SAE International
ISBN: 0768099463
Category : Technology & Engineering
Languages : en
Pages : 320

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Book Description
What is acoustics? What is noise? How is sound measured? How can the vehicle noise be reduced using sound package treatments? Pranab Saha answers these and more in Acoustical Materials. Acoustics is the science of sound, including its generation, propagation, and effect. Although the propulsion sources of internal combustion engine (ICE) vehicles and electric motor-powered vehicles (EV) are different and therefore their propulsion noises are different, both types of vehicles have shared noise concerns: Tire and road noise Wind noise Vehicle noise and vibration issues have been there almost from the inception of vehicle manufacturing. The noise problem in a vehicle is very severe and is difficult to solve only by modifying the sources of noise and vibration. Sound package treatments address the noise and vibration issues along the path to reduce in-cabin noise. In Acoustical Materials, readers will grasp the science of reducing sound and vibration using sound absorbers, sound barriers, and vibration dampers. Sound provides information on the proper operation of the vehicle, but if unchecked, can detract from the consumer experience within the vehicle and create noise pollution outside the vehicle. Acoustical Materials provides essential information on the basics of sound, vehicle noise source, how these are measured, how vehicle owners perceive sound, and ultimately, how to solve noise problems in vehicles using sound package materials.

Measuring Directional Velocity in Water Waves with an Acoustic Flowmeter

Measuring Directional Velocity in Water Waves with an Acoustic Flowmeter PDF Author: R. H. Multer
Publisher:
ISBN:
Category : Hydraulic engineering
Languages : en
Pages : 40

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Book Description