Noise Calc

Noise Calc is a calculator designed to quickly estimate noise levels in outdoor environments and semi-reverberant fields.

It is a useful tool for acoustic technicians in the field, as well as for other professionals dealing with machine noise. We have specifically designed a section for those who design and install heat pumps, air handling units (AHUs), chillers, and other noisy outdoor machinery.

The first section performs logarithmic summation in decibels: this is useful, for example, when multiple machines are nearby, and their known sound energy levels need to be summed (dB values must be added with dB, or dBA with dBA; sound power levels (Lw) can be summed together; sound pressure levels (Lp) can also be summed, but only if measured at the same distance from the source).

The second section performs a logarithmic difference in decibels: this is useful when the ambient pressure level and residual pressure level are known, helping to determine the energy level of the sound source at a given point.

The third section evaluates sound pressure attenuation with distance: if the pressure level (Lp) in decibels is known at distance d1, the result at d2 can be estimated (however, measurements taken with a phone should be avoided, and care must be taken to ensure that d1 is not too close to the source and that d2 is not affected by sound reflections).

The fourth section evaluates sound propagation in free-field conditions, considering the sound power level (Lw) of the source and whether it is near one, two, or three surfaces (excluding reflections from other objects).

The fifth section estimates the noise reduction effect of a sound-insulating barrier. It performs a simplified frequency-by-frequency calculation and returns the number of decibels by which the noise will be reduced (if the frequency is unknown, 500 Hz is typically used).

The sixth section is particularly useful for technicians and installers of outdoor machinery. Given the data from the technical sheet (either power or pressure at the manufacturer-declared distance), the machine's position near one or more surfaces, and the distance to the nearest neighbor's window, the app will indicate whether there are significant issues in complying with municipal noise zoning regulations).

The seventh section allows for a differential limit calculation.

The eighth section evaluates sound propagation in a semi-reverberant field.