Testing methodology Test Gear: Laptop: Acer Aspire 5024WLMi (AMD Turion 64-bit 3000+, 512MB DDR, 80GB HD)
Soundcard: Creative Labs SB Live! 24-bit External
Microphone: IBF-Akustik EMM-8, serial number 31070504
SPL-calibrator: IBF-Akustik SC-1, serial number 0503003
Programs used: TrueRTA, SpectraPro, ETF5
I measured the frequency response of the soundcard using RMAA 5.5 program and it was +/- 0.3 dB 10 Hz - 15 kHz. Without a correction file, the frequency response of the microphone is +/- 1 dB 10 Hz - 20 kHz or +/- 0.3 dB 10 Hz - 5 kHz. With a correction file both soundcard and microphone frequency responses are corrected to flat. Microphone was calibrated on 31.7.2005 by IBF-Akustik, the reference microphone used was B&K 4133. The measured frequency response of the pre amp is +/- 0.1 dB 10 Hz - 20 kHz. The frequency response of the whole measuring chain is therefor better than +/- 1 dB 10 Hz - 20 kHz.
The SPL-calibrator gives a 94 dB @ 1 kHz signal with a +/- 0.5 dB accuracy. The calibrator was calibrated on 17.8.2005, the reference calibrator used was Quest CA-22. I did the calibration for the absolute SPL indoors at the ambient temperature of around 24 degrees Celsius. The SPL-calibrator was originally calibrated at this temperature. The atmospheric pressure was around 1035 hPa (Finnish weather service), which is very close to the 1007 hPa where the calibrator was originally calibrated. The atmospheric correction for the calibrator is around 1 dB / 200 hPa. The microphone is practically independent for variations in temperature and atmospheric pressure. A hairy windshield was used around the microphone, which helped to eliminate most wind noise (wind noise mainly occurs at very low frequencies).
