1. Thebroadbandsourceisawhitenoiseelectronicsignalfedtotheacousticdrivers. ThepartialOASPL(POASPL)of thesignalmeasuredover400-3000Hzissetatthereferencemicrophone. Allacousticpressuresateachfrequencyare then measured simultaneously. The highest POASPL achievable for all liners at the reference microphone is currently 140 dB [1]. 4. Multitone
2. ThetestmatrixforthesixsamplesisshowninTable2,wherethedifferentsourcetypesarelistedalongwithSPL test conditions for each. Please note that the broadband source is referring to the POASPL for the frequency range of interest. For all source types, 400-3,000 Hz is captured, where the swept-sine source has a frequency resolution of ∼5 Hz, while the stepped-sine source has a frequency resolution of 200 Hz. The broadband source has a signal analysis bin width of 6.25 Hz. For the multitone test conditions, source excitations of multiple frequencies utilize the samefrequenciesthatwereusedforsingle-discretetoneswiththestepped-sineapproach. Additionally,"HG"refersto harmonic frequency groups, while "NHG" refers to nonharmonic frequency groups. SPL cases of 120/140 dB and 140/120 dB refer to alternating SPL tones between simultaneously excited frequencies of a given multitone condition, where 120/140dBreferstoalternatingdBvalues of 120, 140, 120, and vice versa for 140/120 dB.
3. Frequency (Hz) 500 1000 1500 2000 2500 3000 0