ISBN-13: 9783319857688 / Angielski / Miękka / 2018 / 429 str.
ISBN-13: 9783319857688 / Angielski / Miękka / 2018 / 429 str.
"This is essentially a mid-level book as far as theory is concerned and a practical guide for everyday work in the field. ... this book should be recommended to students and especially practitioners with scarce access to expensive tools." (Computing Reviews, November, 2017)
Chapter 1. INTRODUCTION
1.1 Acoustical measurements
1.2 Instantaneous and effective (RMS) value
1.3 Sound pressure level
1.4 Equivalent level
1.4.1 Stabilization time for Leq
1.5 Weighted levels
1.6 Exceedance levels
1.6.1 Stabilization time for exceedance levels
1.7 Spectrum analysis
1.7.1 Constant percentage spectrum analyzer
1.7.2 Line spectrum analyzer
1.7.3 Line spectrum and time-frequency uncertainty
1.7.4 Line spectrum and power spectral density1.7.5 Band filters
1.7.6 Transient response of band filters
1.7.7 Parseval’s identity
1.7.8 Effect of spectrum tolerance on Parseval’s identity
1.7.9 Weighted levels computed from one-third octave bands
Chapter 2 UNCERTAINTY
2.1 Introduction
2.2 Resolution, precision, accuracy
2.3 Measurement method and procedure
2.3.1 Direct and indirect measurement methods2.4 Measurement model
2.5 Uncertainty
2.5.1 Type A Uncertainty
2.5.2 Type B uncertainty
2.5.3 Expanded uncertainty
2.5.4 Combined standard uncertainty
2.6 Examples
2.6.1 Relationship between uncertainties in level and pressure
2.6.2 Uncertainty in the correction of environmental conditions
2.6.3 Uncertainty in the calculation of the equivalent level
2.6.4 Uncertainty in A-weighting computed from octave spectrum
2.6.5 Uncertainty in the measurement of sound transmission loss
2.7 Uncertainty and resolution
2.8 Uncertainty and systematic error
2.8.1 Additive systematic error
2.8.2 Multiplicative systematic error2.8.3 Non linear systematic error
2.8.4 Uncorrected systematic errors
2.9 Chain calculation of uncertainty
Chapter 3 DIGITAL RECORDING
3.1 Introduction
3.2 Digital audio
3.3 Sampling
3.4 Digitization
3.5 Signal-to-noise ratio
3.6 Low-level distorsion
3.7 Dither
3.8 Jitter
3.9 D/A and A/D conversion
3.9.1 Digital / analog conversion
3.9.2 Analog / digital conversion
3.10 Pulse code modulation (PCM)
3.11 Differential pulse code modulation (DPCM)
3.12 Delta modulation (DM)
3.13 Sigma-delta modulation (SDM)
3.14 Digital recording devices
3.15 Sound file formats
3.15.1 WAV format
3.15.2 FLAC format
3.16 Project files
3.16.1 AUP format
3.16.2 AU format
3.16.3 AUF format
3.16.4 External access to audio data
3.17 Recording and storage media3.17.1 Hard disk
3.17.2 Flash memory
3.17.3 Optical discs
3.17.4 Digital audio tape (DAT)
3.18 File systems
3.18.1 FAT 32
3.18.2 NTFS
3.18.3 EXT4
3.18.4 HFS+
3.18.5 UDF
3.19 Long-term preservation
3.20 Conclusion
Chapter 4 DIGITAL AUDIO EDITING
4.1 Introduction
4.2 Audacity
4.2.1 Opening an existing file
4.2.2 Recoding sounds
4.2.3 Generating signals
4.2.4 Adding new tracks
4.2.5 Saving a project
4.2.6 Selection
4.2.7 Labels
4.2.8 Selection in the presence of labels
4.2.9 Calibration tone
4.2.10 FFT filters
4.2.11 Spectrogram and spectrum analysis
4.2.12 Noise removal
Chapter 5 TRANSDUCERS
5.1 Microphones
5.2 Polarization
5.3 Preamplifier
5.4 Sound fields
5.4.1 Free field
5.4.2 Diffuse field
5.4.3 Pressure field
5.4.4 Stationary field
5.5 Microphones and sound fields
5.6 Frequency response5.7 Directional response pattern
5.8 Noise
5.9 Distortion
5.10 Micromachined microphones
5.10.1 Frequency response
5.11 Audiometric earphones
5.12 Omnidirectional sources
Chapter 6 DIGITAL SIGNAL PROCESSING
6.1 Discrete signals6.2 Discrete impulse
6.3 A signal as its convolution with a discrete impulse
6.4 Discrete systems
6.5 Finite- and infinite-impulse-response systems
6.6 Difference equation of a discrete system
6.7 Frequency response of a discrete system
6.8 Z transform of a discrete signal
6.9 Z transform of a difference equation6.10 Z transform of a convolution
6.11 Z transform and frequency response
6.12 Solution of a difference equation
6.13 Poles and stability of a discrete system
6.14 Inversion of a rational z transform
6.15 Continuous- to discrete-system bilinear conversion
Chapter 7 BASIC ALGORITHMS FOR ACOUSTICAL MEASUREMENTS
7.1 Introduction
7.2 Opening a .wav file
7.3 Energy average and equivalent level
7.4 Calibration
7.5 Energy envelope
7.6 A weighting
7.7 Statistical analysis
Chapter 8 SPECTRUM ANALYSIS
8.1 Introduction
8.2 Spectrum analysis paradigms
8.3 Digital filters
8.4 Discrete Fourier transform (DFT)
8.5 Fast Fourier transform (FFT)
8.6 Spectrum analysis with the FFT
8.6.1 Line spectrum analysis
8.6.2 The problem of frequencies close to Fs/2
8.6.3 The problem of subharmonic frequencies8.6.4 Precise detection of pure tones
8.6.5 Windows
8.6.6 FFT band spectrum analysis
8.6.7 Spectral density and spectrum averaging
8.7 FFT filters
8.8 Some applications of the FFT
8.8.1 Determination of tonality
8.8.2 FFT convolution
8.8.3 FFT correlation
8.8.4 Critical band filters8.8.5 Determination of transfer functions
8.9 Contrast of algorithms for use in measurments
8.9.1 International Standard IEC 61260
8.9.2 Contrasting algorithms
8.9.3 Procedure
8.9.4 Sound card calibration
8.9.5 Verification of the analyzer response
8.9.6 Contrast of different algorithms
8.9.7 Results
8.9.8 Conclusion
Chapter 9 TESTING OF DIGITAL RECORDERS
9.1 Introduction
9.2 Specifications of the digital recorder
9.3 Tests
9.3.1 Frequency response
9.3.2 Noise
9.3.3 Linearity
9.3.4 Transient response
9.3.5 Uncertainty9.3.6 Conclusions
Further readings
Appendix 1 Glossary and definitions on metrology
Appendix 2 Fundamentals of Statistics
Appendix 3 Statistical dispersion of the RMS value of a stationary noise as a function of the integrating time
Appendix 4 Statistical dispersion of the RMS value of a non-stationary noise as a function of the integrating time
Appendix 5 Statistical dispersion of percentiles
Appendix 6 Envelope of a filtered noise
Appendix 7 Transient response of a third-order bandpass filter
Appendix 8 Combined uncertainty
Appendix 9 Example calculation of uncertainty in the case of a non-linear systematic error
Appendix 10 The sampling theorem
Appendix 11 Structure of a FLAC file
Appendix 12 Document type definition (DTD) for Audacity project files
Appendix 13 Brief description of Scilab
Appendix 14 Fast Fourier transform (FFT)
Appendix 15 Parseval’s identity and symmetry of the DFT
Appendix 16 Spectrum of window functions
Index
Federico Miyara graduated as an Electronic Engineer from the Universidad Nacional de Rosario (UNR) in 1984. He then joined the faculty of his alma mater, first as an assistant teacher and later as an associate professor. There, he founded the Laboratory of Acoustics and Electroacoustics and has served as its director for more than 20 years. Over the years, he has led several postgraduate courses at the UNR, as well as at other universities in Argentina, Spain, Chile, Uruguay and Bolivia.
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.
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