Engineering Acoustics. Malcolm J. Crocker

with an air gap of width d.Figure 12.9 Theoretical transmission loss for a double panel predicted by Lo...Figure 12.10 Design of double‐panel system: (a) straight‐through studs; (b) ...Figure 12.11 Transmission loss of double‐leaf and of single‐leaf gypsum boar...Figure 12.12 Wavenumber diagram for a simply‐supported beam.Figure 12.13 Wavenumber diagram for a simply‐supported plate.Figure 12.14 Wavenumber diagram for a hard‐walled rectangular room.Figure 12.15 Mode number counts for beam, plate and room.Figure 12.16 Modal densities for beam, plate and room.Figure 12.17 Spectral density of random force and square of admittance |Y|² ...Figure 12.18 Modal overlap factor definition.Figure 12.19 A band of force and the resonance curves of the resonators that...Figure 12.20 (a) Sketch of a multi‐resonator system response |Y|² to a broad...Figure 12.21 Simple plot of radiation efficiency of a simply‐supported panel...Figure 12.22 Radiation loss factor for a simply‐supported panel.Figure 12.23 Acceleration response of panel driven by a point force.Figure 12.24 (a) Partition panel wall connected to a room; (b) Power flow fr...Figure 12.25 Calculated sound pressure level in room.Figure 12.26 Block diagram showing power flow between two resonant systems l...Figure 12.27 Block diagram representing power flows between coupled systems ...Figure 12.28 Experimental values of transmission loss of 1/8 in. (3.175 mm) ...Figure 12.29 Transmission loss for a double aluminum panel, (panel thickness...Figure 12.30 Transmission loss for a double aluminum panel system of differe...Figure 12.31 Panel acceleration response relative to mass law. ○ experiment;...Figure 12.32 Transmission loss for a double aluminum panel with and without ...Figure 12.33 (a) The cab model split into its separate elements. (b) Power f...Figure 12.34 (a) Attenuation of a sealed box containing 1.2 m² of absorbing ...Figure 12.35 Theoretical prediction of the attenuation of an idealized truck...Figure 12.36 Experimentally measured attenuation of the sealed model enclosu...Figure 12.37 Effect of optimization on TL (− − − before optimization, ——— af...Figure 12.38 Chart for determining the overall sound transmission loss, TL₀,...Figure 12.39 Two common construction faults which allow direct air paths to ...Figure 12.40 Typical noise control measures for piping in buildings.Figure 12.41 Mechanical flanking paths.Figure 12.42 Schematic representation of a typical transmission suite.Figure 12.43 Schematic of the apparatus used to measure normal‐incidence TL ...Figure 12.44 A ¼‐in. (6.4 mm) glass sound transmission loss and STC contour;...Figure 12.45 Sound transmission through some common building materials: 100‐...Figure 12.46 Impact sound transmission measurement procedure.Figure 12.47 Examples of tapping machine levels [20]. The concrete slab is 1...Figure 12.48 Typical wall assemblies using gypsum boards: (a) Single 2 × 4 w...Figure 12.49 Typical Floor/Ceiling Assemblies: (a) Carpet and pad, 3/8″ part...Figure 12.50 A typical floating concrete floor construction of the type comm...Figure 12.51 Sound reduction index of floating floor [129].Figure 12.52 Recommended door seal designs.Figure 12.53 Examples of outdoor noise insulation provided by windows.Figure 12.54 Typical noise and vibration control techniques in a mechanical ...Figure 12.55 Typical wind velocity profiles in city and open country regions...Figure 12.56 Wind flow around a building. (a) section view and (b) plan view...Figure 12.57 Schematic diagram of airflow patterns around a bluff‐body or bu...Figure 12.58 Classification of dynamic effects from wind [137].Figure 12.59 Main types of wind‐induced oscillations: (a) vibration due to t...Figure 12.60 Telecommunications tower with mass distribution, stiffness dist...Figure 12.61 Fundamental frequency f_e of tall buildings.Figure 12.62 Various types of damping [137].Figure 12.63 Friction dampers used in the load‐bearing structure of the now‐...Figure 12.64 Photographs of tuned mass damper (TMD) balls; (a) in Skyscraper...Figure 12.65 Human perception of building vibration due to wind.

      13 Chapter 13Figure 13.1 Typical residential installation of heating, cooling, humidifyin...Figure 13.2 Typical residential installation of a split‐system air‐to‐air he...Figure 13.3 Typical residential installation of heating and cooling equipmen...Figure 13.4 Sources and paths of noise and vibration from a centrally locate...Figure 13.5 (a) Terminology used to describe HVAC system ductwork. (b) (1) g...Figure 13.6 Typical paths in HVAC systems [20]. 1: Structure‐borne path thro...Figure 13.7 Example of an air‐handling unit room with numerous acoustical an...Figure 13.8 The AHU with a greatly improved installation [25]. 1. Keeping a ...Figure 13.9 Frequency ranges of likely sources of sound‐related complaints [...Figure 13.10 Frequencies at which different types of mechanical equipment ge...Figure 13.11 Illustration of a typical HVAC sound spectrum for occupied spac...Figure 13.12 Components of a centrifugal fan.Figure 13.13 Exploded view of a typical axial‐flow fan.Figure 13.14 The three principal types of high‐efficiency centrifugal fans....Figure 13.15 Inline fan sound power level comparison [25]. ibid © ASHRAE Sch...Figure 13.16 A‐weighted sound power level test data for a typical plenum fan...Figure 13.17 Inlet and discharge octave band L_w values for a 925 mm plenum f...Figure 13.18 Sound power level comparison for three types of centrifugal fan...Figure 13.19 Inlet one‐octave band sound power levels L_w of three types of p...Figure 13.20 Sound power level comparison between two prediction methods for...Figure 13.21 Sound power level comparison between two prediction methods for...Figure 13.22 Guidelines for centrifugal fan installations [20]. Notes: 1. Sl...Figure 13.23 Vibration isolation suspension for propeller fans. Note: Positi...Figure 13.24 Noisy and quiet installation of ceiling‐mounted exhaust fans [2...Figure 13.25 Line diagram illustrating the major components of an HVAC syste...Figure 13.26 Guideline for VAV unit installation [25]. Note: Parallel or sid...Figure 13.27 This figure shows a set of curves giving guidance for the selec...Figure 13.28 Acoustical comparison of various building core area layouts [25...Figure 13.29 Mechanical room on ground floor of building. ibid © ASHRAE Scha...Figure 13.30 Very noisy rooftop unit installation [25]. ibid © ASHRAE Schaff...Figure 13.31 Very quiet rooftop installation [25]. ibid © ASHRAE Schaffer Gu...Figure 13.32 A typical floating concrete floor construction of the type comm...Figure 13.33 Floating floor vibration isolators‐molded precompressed glass f...Figure 13.34 Constructional details of floating floors at the base of dividi...Figure 13.35 Relationship between isolation efficiency, disturbing frequency...Figure 13.36 General machinery vibration amplitude severity chart (1 mil = 0...Figure 13.37 Isolation and support of concrete inertia bases from a mechanic...Figure 13.38 Structural support for vibration control of rooftop equipment [...Figure 13.39 A typical method used to provide horizontal restraint for a vib...Figure 13.40 Typical standing wave resonance as observed in a spring isolato...Figure 13.41 Length of flexible pipe connector required to give adequate vib...Figure 13.42 Duct and pipe penetrations through walls. Note: Support pipes a...Figure 13.43 All piping connections to a vibrating source should be resilien...Figure 13.44 Schematic representation of an acoustical plenum chamber.Figure 13.45 Schematic of end‐in/end‐out plenum.Figure 13.46 Speaking tube effect between adjacent rooms and possible soluti...Figure 13.47 Attenuation for lined and unlined sheet metal ductwork [25]. ib...Figure 13.48 Breakout transmission loss for three types of sheet metal ductw...Figure 13.49 In‐duct attenuation for various duct liner thicknesses [25]. ib...Figure 13.50 Variation of static pressure drop across a typical splitter‐typ...Figure 13.51 Construction of typical commercial silencers including a circul...Figure 13.52 Attenuation and noise generation characteristics of typical cyl...Figure 13.53 Duct silencer placement near a mechanical room wall [25]. ibid ...Figure 13.54 In‐duct attenuation of duct silencers and lined ductwork [25]. ...Figure 13.55 Comparative insertion loss of dissipative, film‐lined, and reac...Figure 13.56 Attenuation (dB) at duct termination due to end reflection loss...Figure 13.57 This shows the expected “end reflection” losses for rectangular...Figure 13.58 This shows the attenuation observed in mitre bends in ducts whe...Figure 13.59 Attenuation of rectangular elbows with and without turning vane...Figure 13.60 Attenuation of rectangular and radius elbows (lined and unlined...Figure 13.61 Velocity‐generated sound of duct mitre elbows [20]. Note: Compa...Figure 13.62 A‐weighted sound pressure levels measured 1.5 m (5 ft) from sur...Figure 13.63 (a) Proper and improper airflow condition to an outlet; (b) eff...Figure 13.64 Typical generated sound pressure levels vs. flow velocity for s...Figure 13.65 This figure can be used to estimate generated sound pressure le...Figure 13.66 The effect of installing a damper behind a grille; (a) Without ...Figure 13.67 The effect of partially closing a damper on a 50 cm × 50 cm (20...Figure 13.68 Velocity‐generated sound of 60 cm by 60 cm volume damper [20]. ...Figure 13.69 If possible, dampers should be placed well back behind outlet g...Figure 13.70 Duct breakout.Figure 13.71 Duct breakin.Figure 13.72 Typical radiated sound power levels for dual‐inlet mixing boxes...Figure