ETC.. Now you can have an Energy Time Curve function on your iPhone. Developed by the team that brought you the Audio Toolbox, the ETC function lets you analyze room decay and speaker alignment, see room reflections graphically and even compute RT60 time. It includes ANSI A, C, and octave band filters, scalable graphics, and cursors to read out time and distance, as well as to compute RT60 time directly from the graph.In External Trigger mode, ETC waits for a signal that is above the threshold value on the settings page, and then records incoming acoustic signal. Normally this signal is an impulse, but can be created by popping a balloon, or even snapping your fingers. The decay curve is displayed, using a window that you select of 20ms, 40ms, 80ms, 160ms, 320ms, 640ms, 1.25s, or 2.5s. Once the ETC graph is on the screen, drag one finger to see a cursor that reads out the exact dB level and time in ms, or the equivalent feet or meters, selectable on the settings page.Touch the screen with two fingers to make two cursors that define the starting and ending times for the RT60 calculation. These cursors are connected by a line showing the exact slope that is being computed.In Internal Trigger mode, ETC creates a pop and starts the graph at exactly that time. Then, you can see the exact time that the impulse arrives, to see the initial delay time, and early reflections, relative to the pop. Note that to use this mode, you have to use an external mic and route the iPhone output to the input of the sound system. This is because when you plug a cable into the headphone jack, the external mic is disabled. We are working on a calibrated microphone and cable setup that will allow this functionality. Check our Web site for availability and cost.ETC comes calibrated for the typical iPhone built-in mic level, but you can calibrate it yourself if you have access to a a calibrated sound level meter.ETC works best on iPhone 3G, but can also work on second generation iPod Touch if an external mic is used.
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