Find the delay between an "almost" echoing signal in a recoding

Question

I use the SoundWire software with an Android phone(audio over network), that's all good but, there is a delay. What I want to know is how much of a delay it is between the audio coming from my computer monitor and the audio created by my phone. I thought I could take a recording with Audacity and then zoom into the waveform but, alas I didn't find any in-the-face clues in the waveform.

Is there a commercial software or some technique that one of you Audio Wizards out there knows to find the delay between an essentially echoing signal in a recoding.

Answer 1

If I understand you correctly, you have two sources of audio, one of which is delayed by a small amount, and you want to find the delay between them.

To accomplish this with minimal equipment (I'm assuming you don't have equipment like oscilloscope, audio analyzer, etc), you can try to run both these audio sources into different channels of your soundcard, record an impulse, and the look at the offset.

In greater detail: take a line out from your computer (or whatever is driving your "computer monitor"; are you really using your computer monitor's speakers?) and take the headphone out of your phone, run both of these to a soundcard on a different computer, and record with your software of choice. Then get/make an audio file with a sharp impulse in it, could be as simple as a beep, snare hit, etc. Play the file, and look at the recording to measure the offset. It won't be the most accurate characterization, but close enough for practical purposes.

Answer 2

Uh, clap your hands once. If that doesn't give you an in-the-face clue in the audio waveforms, I don't know what will.

Movie takes use clapperboards for a reason.