I was asked by Joelle to post my question here for technical support after asking through Amazon for pre-sales support.
I’d like to know if the SEN-12642 Sound Detector has a fast response time, preferably less than 1ms, between the time a sound wave reaches the mic and when the LED indicates the presence of sound greater than the threshold. I’d like to use this to test audio/video sync by playing a special video file (loud noise such as a clap every second or so, along with a video frame that flashes all white), then aiming a high speed camera at both the monitor and the sound detector board. I can then look at the video frames from the high speed camera to determine how many frames pass between the white flash and the LED lighting up on the sound detector to see how close they are. I’ll be measuring time differences of only a few milliseconds, using a camera framerate of about 1,000 fps, so in order for this to work, the LED on the board needs to come on no more than about 1ms after the loud sound starts.
The response time of any audio detector depends greatly on the audio signal envelope, frequencies and amplitude, which you did not specify.
However, the AUDIO output of the sound detector results from a single stage LMV324 amplifier with a default gain of 100. The gain-bandwidth product of the LMV324 is 1MHz, which means that the rolloff frequency is 10 KHz.
Correction:
The amplifier should therefore faithfully follow a 10 kHz sine wave audio signal, which peaks every 0.1 millisecond. Thus, the baseline response time for AUDIO output of the unmodified board can be roughly estimated as 0.1 millisecond, faster for certain signals and slower for others.
I had planned to create a sound with a fast attack, like a percussion instrument, or clap. But would another type of sound be better for triggering the SEN-12642? Maybe longer in duration instead of an impulse? I would also like for the LED to stay lit for at least 1-2ms, just so it’s not so fast as to avoid showing up on the high speed camera.
The SEN-12642 is described as follows “The Sound Detector not only provides an audio output, but also a binary indication of the presence of sound, and an analog representation of its amplitude”.
There is no indication that high speed response or a particular type of sound are design considerations. Your web searches for alternatives could include something along the lines of “high speed” or “fast response” or “remote trigger”.
I think you’re just going to have to try one and see, that’s the only way you’ll know for sure. The whole board is analog so it should be pretty fast and it’s less than $13.00 so if it’s not fast enough, you’re not out much. Plus, maybe it works for another project.