The Measure Setup screen can be accessed by tapping on the Measure screen.
Stimulus Type controls the “sweep” portion of the test signal (chirp + sweep) used to measure the audio system.
Use a logarithmic sinusoid sweep as the stimulus signal. This is the default mode. It requires a connection to the audio system in order to play the test signal.
Pink noise stimulus is provided for interest sake. Measurements based on pink noise will have a signal to noise ratio that is lower than sine sweeps. The measurement process is identical to sine sweep (this is not a real time analyzer (RTA) mode).
HouseCurve uses coherent averaging. This has an interesting effect on Pink Noise measurements. In a sonically treated room, such as one with sound absorbing panels on the walls, Pink Noise noise measurements will closely match Sine Sweep measurements. In a more typical “reflective” room, Pink Noise magnitude measurements tend to be lower above ~2 KHz. The degree to which the Pink Noise and Sine Sweep measurements match is an indication of how “dead” the room is.
This mode also uses a logarithmic sinusoid sweep, but it does not require a connection to the audio system. Instead, the test signal must be manually transferred to the audio system (ex: SD card, CD, streaming library). The audio system is responsible for playing the test signal and HouseCurve will listen for it when measure is tapped.
The test signal can be exported to a WAV file when this mode is selected. The chirp and sweep channel setting will be used to produce the test signal file.
The average built in iPhone/iPad is reasonably flat, but begins to roll off below ~60 Hz and above ~16 KHz. Internal Mic Compensation applies a moderate boost to correct this. The boost curve is +6 dB at 30 Hz, tapering to zero at 60 Hz. Likewise, at 16 KHz, the boost is zero and this increases to 6 dB at 20 KHz.
It’s worth keeping in mind that the iPhone/iPad can still “hear” below 60 Hz and above 16 KHz, it’s just not as sensitive. Internal Mic Compensation brings the measured response closer to what you would get with a calibrated extrnal mic.
HouseCurve supports calibrated external microphones. Available calibrations will be displayed in the list. Select None to disable calibration.
Microphone calibrations can be loaded tapping + at the top of the External Mic Calibration screen. Calibrations can be removed by tapping Edit.
HouseCurve uses the following curve file format for microphone calibration.