Using the programs from
dsputils.zip (see description
here), I have created a script for a fairly complete set of headphone measurements. I am not sure if anyone finds this useful, though, since the user friendliness and the documentation are lacking, but maybe someone will find it interesting:
hptest.zip
It uses the following input files:
- the test signals recorded from the headphone (the test does take a few minutes, so the sample could be optimized for shorter length). resample.txt needs to be set up with the correct start time and gain parameters so that the 1 kHz tone at the beginning of the file starts at exactly 1 second, and has an amplitude of 0 dBFS
- the impedance test file (a loopback recording using a device with a known resistive output impedance; the test signal consists of two MLS loops, the headphone load needs to be connected during the second one)
- global equalization IR file (it is applied to all measurements)
- frequency response equalization IR file (it is only applied to the FR graph)
The graphs created include:
- frequency response (from impulse response, equalized; it does not average the response from multiple positions, though, which would be a useful feature)
- CSD (left and right channel)
- 500 Hz THD spectrum at 90 and 100 dB SPL (note: for the SPL values to be correct, the test file should be played at a volume setting at which 0 dBFS = 105 dB SPL - the drivers need to be able to handle this, and a long sine sweep at 100 dB)
- 55 Hz + 2000 Hz 4:1 IMD spectrum at 90 and 100 dB SPL
- 15000 + 16000 Hz 1:1 IMD spectrum at 90 and 100 dB SPL
- THD vs. frequency at 90 and 100 dB SPL
- THD vs. level at 50 Hz, from 80 to 105 dB SPL
- group delay
- impedance vs. frequency
The package also contains some sample graphs. However, since I did not use a high quality microphone and dummy head or artificial ear, these are not particularly accurate, and are really only examples.