My thoughts on acoustical data

Kundt's tube is an experimental acoustical apparatus invented in 1866 by German physicist August Kundt for the measurement of the speed of sound in a gas or a solid rod. The experiment is still taught today due to its ability to demonstrate longitudinal waves in a gas.

The same type of instrument is used today called an Impedance Tube. *

Impedance tubes can only measure acoustical longitudinal waves. Although longitudinal waves are encountered in the rooms where we work and live, they are not the only standing waves present in Real-world acoustics.

Real-World acoustical data in architectural acoustics is out of date by as much as 60 years. Little research has been undertaken to discover why there are so many errors and wrong conclusions based on inferior testing methods (cheap, easy, and invalid). There's far more that we don't know than we know. The field is riddled with inconsistencies, myth, and opinion. We need the latest data, scientifically obtained, to correct the industry at large. Modeling programs are based on the flawed data and result in compound errors.

I must make a point here about the popular online modal calculators. Most only display axial modes - longitudinal. By limiting the modal functions of an enclosure they risk compound errors in calculation. They are therefore flawed and will lead to wrong conclusions.

I have worked on my room mode calculators for 16 years, building upon Jeff Smanski's work. They're available on my resources page for free download.

Summary:

Always base your work on the best data available - from Laboratory Testing... and don't be a Kundt (Billy Butcher).