Indian Space Research Organization - Extent of spectral spread 1/3rd Octave Analysis I am a scientist at Indian Space Research Organization (ISRO) and will be representing my team. We work on Telemetry and Data Handling units for our Launch Vehicles.
We are preparing for our upcoming SSLV Launch (Small Satellite Launch Vehicle) and need some information to confirm if we are at par with the industry, or if we need to switch to better available options.
It would be really helpful if you share the name of the company which excel in software or equipment for 1/3rd octave analysis of acoustics signals, that you know of or have used and can vouch for best accuracy.
Please mention what is:

Order of band pass filter

Type of filter (Elliptic/butterworth etc.)

Order of Low pass filter (If one is being used in the design), type of low pass filter, its stop band attenuation and passband ripple.


Your help is duly appreciated.
Warm regards from our entire team at ISRO.

Rekhanshi Varma
Scientist/Engineer 'SC'
Vikram Sarabhai Space Center
Indian Space Research Organization (ISRO)
Office Ph: 04712564741 | Country Code: +91
That's not really a signal processing  question, but here are are some pointers.
3rd octave filters are well defined in ANSI S1.11-2004 and any decent commercial implementation should be fully compliant to the standard. The implementation is rather simple, so compliance isn't much of a problem. It's easy enough to do it yourself and their are ready-made packages in analysis products like Matlab https://www.mathworks.com/help/audio/ug/octave-band-and-fractional-octave-band-filters.html or measurement products like B&amp;K https://www.bksv.com/en/instruments/handheld/sound-level-meter-apps/bz-7132-and-7131-frequency-analysis (no product endorsement intended, but these are reputable names).
One thing to keep in mind: In most real world acoustic problems, the difficult part is NOT the analysis but actually making the measurement and/or data capture. Where and how to place what type of microphones, when and how to capture with what signal, making sure that the signals are neither overdriven nor overly noisy, good signal to noise ratio at all frequencies of interest, good reproducibility, etc.. This requires fare more experience and expertise than the data analysis, so if you want to spend extra money, I recommend you spend it there.
Sound fields are very complicated 3-dimensional phenomena and a microphone only samples a single point in space. Moving a microphone by a few centimeters often makes much more of a difference than any analysis parameter.