The RETSPL values of ISO 389-5 cannot be used to do Extended High Frequency testing that is comparable with the the golden standards Sennheiser HDA200 earphones. The newly determined RETSPL values of the KUDUwave™ are comparable with the golden standards Sennheiser HDA200 headset calibrated to ISO 389-5. The EHF RETSPL values of the KUDUwave™ are 13.5 dB for 9000 Hz, 12.5 dB for 10,000 Hz, 21.5 dB for 11,200 Hz, 25.5 dB for 12,500 Hz, 32.4 dB for 14,000 Hz and 41 dB for 16,000 Hz.
The first study is large enough with a good randomised trial to determine the RETSPL of extended High Frequencies. The RETSPL value of 10 kHz was determined in the second study where the other RETSPL values were validated.