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Measure Setup

The Measure Setup screen can be accessed by tapping Setup on the Measure screen.

Measure setup screen

Chirp and Sweep Channel

The “chirp” and “sweep” sounds of the test signal can be played on different channels (see measurement process). This is mainly used for subwoofer measurements.

Stimulus Type

Stimulus Type controls the “sweep” portion of the test signal (chirp + sweep) used to measure the audio system.

Sine Sweep

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

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.

External Sine Sweep

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.

Internal Mic Compensation

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.

External Mic Calibration

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.

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