Signal Calibration
All facilities were integrated into a custom-made test cart with a flexible arm holding the loudspeaker (Figure1). All stimuli showed linear correlation between the dial value and measured sound pressure level at the reference point, the difference between those two points was significantly (P<0.001). The average dial to reference point difference (DRD) of sound pressure level is near 0 dB (Table 1). Dynamic range of the loudspeaker output was 20-100 dB SPL in SPC and 40-100 dB SPL in OR.