How to create a test to measure end to end audio delay

Question

Lets say I have a program like Skype and I call to my friend. I want to create a test to figure out what is the average delay from the audio, from my mic to his speakers.

I want to measure:

• delay in one instance of time
• delay over longer period (60 s)

Assumptions that i can make:

• at least 8000 samples per second.
• devices are in the same room and network propagation delay is negligible.
• external mic and photo-detector/camera should be used.

Answer 1

I recently ecountered this problem too (about a month ago). This is what I found..

Network delay measuring protocol (NDMP) - little useful free-ware program. I used the same program to measure other VoIP call delay.

You can download it from here: http://www.unforgettable.dk/42.zip ReadMe file is included in .zip file.

Answer 2

We may use audio recording software like adobe audition for this purpose.

• We can use the stereo mix feature of windows to record the mic input and speaker output.

• Start the recording software at both ends, and record some portion of your communication.

• Now compare some prominent portion like sudden jump in audio within this software. You will get approximate delay between these audio files.