Engineering Acoustics. Malcolm J. Crocker

Scale of vibration discomfort from British Standard 6841 and Int...Figure 6.21 Response of building in good condition to vibration (*Rendering ...

      7 Chapter 7Figure 7.1 Idealized noise or vibration‐measuring system.Figure 7.2 Sensitivity of (i) an ideal microphone or accelerometer ______ an...Figure 7.3 Sensitivity of an ideal microphone or accelerometer showing upper...Figure 7.4 Inherent noise floor against upper limiting sound pressure level ...Figure 7.5 Comparison of the dynamic ranges of the same four condenser micro...Figure 7.6 Frequency response of an ideal microphone or accelerometer.Figure 7.7 Comparison of the frequency response ranges of four different dia...Figure 7.8 Cross‐section through a 1‐in. condenser microphone.Figure 7.9 Electret microphone using a thin electret polymer layer deposited...Figure 7.10 Cross‐sectional view of piezoelectric microphone.Figure 7.11 Directivity of a microphone with a protection grid at different ...Figure 7.12 Noise measurements using (a) free‐field microphone and (b) diffu...Figure 7.13 Idealized diagram of vibration transducer.Figure 7.14 Transverse and longitudinal sensitivity of accelerometer.Figure 7.15 Mounting of an accelerometer to reduce cable whip noise.Figure 7.16 Effect of mass loading of an accelerometer on the vibration of a...

      8 Chapter 8Figure 8.1 Tyndall's flames [2]. A long flame may be shortened and a short o...Figure 8.2 Tyndall's smoke jets [2]. The amount of shrinkage exhibited by so...Figure 8.3 Rayleigh's copy of Mayer's paper on sound intensity.Figure 8.4 (a) Arrangement of apparatus for wave calibration by means of the...Figure 8.5 Instantaneous spatial distributions of sound pressure, particle v...Figure 8.6 Sound energy and sound intensity.Figure 8.7 Spatial distributions of instantaneous sound pressure, instantane...Figure 8.8 Idealized monopole source of sound.Figure 8.9 (a) Real intensity fluctuations, (b) Imaginary intensity fluctuat...Figure 8.10 Schematic diagram of sound intensity measurements made with the ...Figure 8.11 Schematic diagram of sound intensity measurements made with the ...Figure 8.12 Microphones arrangements used to measure sound intensity.Figure 8.13 Sound intensity probe with the microphones in the face‐to‐face c...Figure 8.14 Three‐dimensional sound intensity probe for vector measurements;...Figure 8.15 Experimental set‐up for measuring sound intensity, (a) near fiel...Figure 8.16 Illustration of the error due to the finite difference approxima...Figure 8.17 Finite difference error of an ideal p–p face‐to‐face sound...Figure 8.18 Pressure increase on the two microphones of a sound intensity pr...Figure 8.19 Error of a p–p sound intensity probe with half‐inch microp...Figure 8.20 Error level Le due to a phase error φ_e of 0.3° in a plane p...Figure 8.21 Coupler for measurement of the pressure‐residual intensity index...Figure 8.22 Maximum error due to a phase mismatch as a function of the bias ...Figure 8.23 The global pressure‐intensity index ∆_pl determined under three d...Figure 8.24 Effective separation results performed by the manufacturer of th...Figure 8.25 Calibrators for calibration of sound intensity calibration in th...Figure 8.26 Sensitivity and gain adjustment using B&K calibrator 3541Figure 8.27 Phase difference determination between microphone pair using B...Figure 8.28 Use of B&K coupler UA 0914 and calibrator B&K 3541 to verify pha...Figure 8.29 Final verification steps in system calibration using free field ...Figure 8.30 Final verification check to see that the sound pressure level (F...Figure 8.31 Normalized systematic error ϕ_e of a p–u system due to...Figure 8.32 A p–u sound intensity probe.Figure 8.33 Hand‐held probe for surface intensity measurement [84].Figure 8.34 Phase shift Δϕ_x from the finite distance between the microp...Figure 8.35 Transducer arrangement for phase shift determination [82].Figure 8.36 Error E in intensity caused by uncorrected phase shift ϕ [8...Figure 8.37 Sound intensity measured on a segment of (a) a hemispherical mea...Figure 8.38 Typical box surface used in sound power determination with the i...Figure 8.39 Sound power level measured by sound intensity of a Caterpillar T...Figure 8.40 Indoor sound power measurement of a reciprocating compressor [90...Figure 8.41 Automated sound‐intensity system used to measure the sound power...Figure 8.42 Garden tractor used for tests of gated sound power [91].Figure 8.43 Measurements of the sound intensity radiated by a vacuum cleaner...Figure 8.44 Sound intensity vectors measured in two planes near a violoncell...Figure 8.45 Oil pan narrow‐band sound power level spectrum determined from t...Figure 8.46 Comparison of sound power level determined for the oil pan from ...Figure 8.47 Narrow‐band sound power level determined from surface intensity ...Figure 8.48 Comparison of sound power level determined for the oil pan from ...Figure 8.49 Radiation efficiency of the oil pan determined at an engine spee...Figure 8.50 Comparison of diffuse field intensities averaged over narrow fre...Figure 8.51 Experimental set‐up for measurement of transmission loss of a pa...Figure 8.52 Transmission loss of a 3.2 mm thick aluminum panel: ‐‐□‐‐...Figure 8.53 Measured and calculated transmission loss of a composite aluminu...Figure 8.54 The transmitted sound intensity measured with a probe with micro...Figure 8.55 Interlaboratory comparisons according to ISO 140‐3 for a single ...Figure 8.56 Interlaboratory comparison for a single metal leaf window (lower...Figure 8.57 Photograph of the aircraft fuselage in the semi‐anechoic chamber...Figure 8.58 Instrumentation used for the measurement of sound transmission l...Figure 8.59 Transmission loss versus frequency for the back passenger window...Figure 8.60 Sound transmission loss versus frequency for different aircraft ...Figure 8.61 Schematic diagram of the experimental set‐up for the measurement...Figure 8.62 Transmission loss of the cylindrical shell measured by two‐micro...Figure 8.63 Experimental results of radiation efficiency at one‐third octave...Figure 8.64 Layout of the packaging machine [101].Figure 8.65 Sound intensity measurement set‐up.Figure 8.66 Sound pressure measurement set‐up [101].Figure 8.67 Convergence of sound power results [101].Figure 8.68 Signal/noise ratio [101].Figure 8.69 Sound power level (SIL) results from sound intensity method. Sou...Figure 8.70 Comparison of final fixed points and scanning values, final fixe...

      9 Chapter 9Figure 9.1 Source‐path‐receiver model for noise and vibration problems.Figure 9.2 Sources and paths of airborne and structure‐borne noise and vibra...Figure 9.3 Source–path–receiver system showing airborne and structure‐borne ...Figure 9.4 Rigid machine of mass m attached to a rigid massive floor.Figure 9.5 Rigid machine of mass m separated from rigid massive floor by vib...Figure 9.6 Relationship between natural frequency f_n of machine‐isolator‐flo...Figure 9.7 Relationship (for a linear isolator) between forcing frequency f,...Figure 9.8 Machine vibration severity chart showing peak‐to‐peak‐ vibration ...Figure 9.9 Typical ranges of material damping loss factors at small strains ...Figure 9.10 Different ways of using vibration damping materials: (a) free (u...Figure 9.11 Paths of direct and reflected sound emitted by a machine in a bu...Figure 9.12 The two main mechanisms believed to exist in sound‐absorbing mat...Figure 9.13 Typical absorption coefficient vs. octave band frequency charact...Figure 9.14 Sound absorption coefficient α and noise reduction coeffici...Figure 9.15 Effect on the sound absorption coefficient α of placing a 2...Figure 9.16 A Helmholtz resonator consists of a neck of radius r, length L a...Figure 9.17 Sound absorption coefficient vs. frequency for a slotted 20‐cm c...Figure 9.18 Slotted concrete blocks faced with fiberglass and covered with a...Figure 9.19 Geometry for a typical perforated panel absorber.Figure 9.20 Variable airspace perforated panels give broader absorption char...Figure 9.21 Porous absorbing material protected by a thin Mylar (polyester) ...Figure 9.22 Slat type of resonator absorber (normally the mineral wool is pl...Figure 9.23 Sound‐absorbing material placed on the walls and under the roof ...Figure 9.24 Sound absorption coefficient α of a 13‐mm thick acoustical ...Figure 9.25 Acoustical enclosure placed in free field.Figure 9.26 Personnel enclosure placed in a reverberant sound field.Figure 9.27 Machine enclosure placed in a reverberant environment.Figure 9.28 Close‐fitting enclosure attenuation in sound pressure level for ...Figure 9.29 Simplified one‐dimensional model for a close‐fitting enclosure [...Figure 9.30 Theoretical close‐fitting enclosure insertion loss performance [...Figure 9.31 Partial enclosure.Figure 9.32 Decrease of enclosure insertion loss, ΔIL, as a function of the ...Figure 9.33 Enclosures with penetrations (for cooling) lined with absorbing ...Figure 9.34 Basic elements of an acoustical enclosure used for machinery noi...Figure 9.35 Major components and cooling airflow of an air compressor [114]....Figure 9.36 Enclosure for a bandsaw.Figure 9.37 Ready‐made modular materials used to make enclosures and barrier...Figure 9.38 Sound waves reflected and diffracted by barrier and acoustical s...Figure 9.39 Attenuation of a barrier as a function of Fresnel number N for p...Figure 9.40 Freestanding