Delay between Microphone and Speaker in 0 distance...

[rhksgud92]

When I run this simple microphone and sine wave speaker FPGA code, I see constant (0.002 ~ 0.0035 second) delay in 2k sampling rate. 

(Distance between speaker and microphone is almost 0 cm, so there shouldn't be any delay).

I am using NI cRIO-9022 with NI9234 for microphone and NI9269 for speaker.

Is that delay happens because of code problem?

I simulated with several microphones and speakers (even with speaker without amplifier), but there still is delay...

In case of microphone needs a short stabilizing time after getting power, I waited but still there is delay.

Can anyone guess why there is delay? and how can I remove that delay?

(I am not sure I can ask this kind of question here.. Sorry)

[ogk.nz]

I would say that a delay of this size should be negligible depending on your situation, but I would expect it to exist none the less, given that speakers are generally large magnetic coils they will have a delay due to their built in impedance, and even with ~0 distance between the speaker face and the microphone there will be a small distance to travel depending on the depth of the speaker cone, even at 10cm the time to travel that distance would account for 0.005 seconds travel time.