Engineering Noise Control Software

Fundamentals, subjective response to sound and noise criteria (chapter 1,2,3 and 4)

• calculation of speed of sound in liquids, solids, and gasses
• sound power from sound power level and vice versa
• sound pressure from sound pressure level and vice versa
• sound intensity from sound intensity level and vice versa
• addition/subtraction of coherent sound levels
• addition/subtraction of incoherent sound levels
• combining noise reductions where several paths from source to receiver are involved
• loudness in phons and sones given in octave or 1/3 octave band levels
• calculation of NC, NR, NCB, and RC (as well as spectral character) from octave band data
• A-weighted sound levels from octave or 1/3 octave band linear levels
• allowed exposure time (European, USA criteria)
• daily noise dose from dB(A) noise levels and time of exposure to each level
• hearing damage risk calculations using ISO 1999 and Bies/Hanson methods
• Impact noise dose calculations
• Speech interference calculations

Sound power of sources and outdoor sound propagation (chapter 5 & 6)

• sound pressure at specified distance due to monopoles, dipoles, quadrupoles, line sources (coherent and incoherent), and plane sources, given the source sound power or source strength. Reverse calculations are also available.
• outdoor sound propagation – OCMA, CONCAWE, and Aexact analysis, meteorological effects, ground effects (3 procedures), air absorption
• radiation field of a source (indicates whether observer is in near field, geomtric near field, far field, or a transition region)
• sound power from reverberant room measurements
• sound power from field measurements, semi-reververant field (3 methods), near field measurements, (3 methods), vibration measurements

Room acoustics and sound absorption (chapter 7, Appendices 3, 4 and 5)

• resonance frequency, modal density, modal overlap for rectangular rooms
• room absorption (and room constant) from reverberation time and vice versa (Sabine and Millington-Sette)
• room sound pressure levels from sound power of source in room and vice versa, Sabine rooms, flat rooms (specularly and diffusely reflective walls)
• calculation of statistical absorption coefficient averaged over room from data for individual room surfaces
• calculation of statistical absortion coefficient from material flow resistivity and thickness for material layers, porous materials layers with impervious skin, porous material layers with impervious skin, and perforated sheet of just perforated facing
• design of panel sound absorbers given desired absorption coefficients
• empirical method
• analytical method
• calculation of effect on sound levels in a room of adding a specified amount of absorbing material
• determination of optimum reververation times for specified space size and use

Transmission loss, enclosure design, barriers and pipe wrappings (chapter 8)

• TL calculations for single partitions (both Sharpe and Davy/Hansen methods), STC calculations, isotropic panels, ribbed panels
• TL calculations for double partitions (Sharpe and Davy methods), STC calculations, steel or wooden studs
• Calculation of overall TL for a wall with windows, doors, cracks, etc
• Enclosure noise reduction calculations. Includes cooling air flow requirements, effect of cracks and openings, and effect of enslosure internal conditions
• Outdoor barrier noise reduction. Includes diffraction around sides and top, ground absorption and berrier thickness included, point or line sources, wind and temperature gradient effects included
• Indoor barrier noise reduction, barrier of arbitrary orientation in a rectangular room
• Pipe lagging noise reduction (2 calculation methods)

Dissipative and reactive muffler design and duct breakout noise calculations (chapter 9)

• impedance of orifices, expansion chambers and ducts (resistive and reactive)
• Helmholtz resonator design and noise reduction
• expansion chamber noise reduction
• low pass filter (for reciprocating compressors etc.) design and noise reduction
• small engine exhaust design
• pressure drop estimates for specified dissipative or reactive mufflers
• flow generated noise due to silencers and duct bends
• dissipative muffler design, lined duct attenuation calculations for sound absorptive liners with and without impervious and perforated facings, noise reduction due to reflection at inlet and outlet, correction due to effective expansion in line section
• duct breakout and break-in noise calculations
• lined plenum chamber noise reduction calculations
• exhaust stack directivity and noise reduction vs height calculations

Vibration Isolation and Damping (chapter 10)

• mass on spring isolator
• resonance frequency for damped and undamped systems, frequency of maximum displacement, velocity and acceleration
• force trasmissibility as a function of excitation frequency, resonance frequency and damping
• effect of flexibility in the foundation or mounted mass on the transmitted force
• machine mounted on 4 isolators, resonance frequencies calculations
• vibration absorber design, optimum stiffness and damping for specified mass ratio, vibration amplitude and absorber at resonance
• relation between different damping measures (critical damping ratio, loss factor, logarithmic decrement)

Sound power estimates for specific source types (chapter 11)

• fans
• compressors
• cooling towers
• pumps fluid jets
• control valves
• fluid flow in pipes
• boilers
• turbines
• IC engines
• furnaces
• electric motors
• generators
• transformers
• gears