28 engineering calculators - each on its own bench, with live graphs, schematics and slider controls that work as well on a phone in the plant room as on a desk. Every tool ends with the theory behind it.
Decibels, weightings, bands and the physics of sound waves.
Combine incoherent sound sources energetically, or strip background noise out of a measurement.
Convert between levels in dB and physical quantities: pressure, intensity, power, velocity, acceleration, voltage.
IEC 61672 weighting curves, and the overall dB(A) / dB(C) of an octave-band spectrum.
Centre and edge frequencies for 1/1 to 1/24-octave bands per IEC 61260, with filter shapes.
How long is a sound wave? Wavelength, period and wavenumber in air, water and solids.
Ideal-gas speed of sound vs temperature, including the effect of humidity in air.
Frequency shift for a moving source or observer - with an audible pass-by simulation.
Outdoor propagation, barriers and hearing-conservation metrics.
Geometric spreading from point and line sources: the inverse-square law in practice.
Predict sound pressure level from sound power, directivity and room absorption. Find the critical distance.
Path difference, Fresnel number and the Maekawa estimate for a thin screen.
ISO 9613-1 air absorption coefficient vs frequency, temperature, humidity and pressure.
OSHA and NIOSH dose, TWA and the EU daily exposure level L_EX,8h for a working shift.
Reverberation, room modes, partitions and resonators.
Octave-band RT60 of a rectangular room from its surface finishes and occupancy.
Axial, tangential and oblique standing waves of a rectangular room, with pressure maps.
Mass law, coincidence frequency and a sound reduction index estimate for single-leaf panels.
Resonance of a cavity and neck - bass traps, bottles, ports and silencers.
Standing-wave frequencies of open and closed tubes with end corrections.
Oscillators, isolation, absorbers and continuous structures.
Displacement, velocity and acceleration at a frequency - peak, RMS and peak-to-peak - on a tripartite nomograph.
Natural frequency of a single-degree-of-freedom system from mass and stiffness or static deflection.
Bode magnitude, phase and Nyquist plots of a damped oscillator: receptance, mobility, accelerance.
Transmissibility and isolation efficiency of resilient mounts - and the deflection you need.
Den Hartog optimal tuning and damping of a dynamic vibration absorber.
Euler–Bernoulli bending modes for common boundary conditions, with animated mode shapes.
Condition monitoring, balancing and severity assessment.
BPFO, BPFI, BSF and FTF of rolling-element bearings, plotted on a simulated spectrum.
Permissible residual unbalance per ISO 21940-11 (formerly ISO 1940-1).
Classify broadband machine vibration into evaluation zones A–D (ISO 10816 style).
FFT set-up, window functions and waveform statistics.