acquire sound data time does not match with the waveform graph

[camr_tna]

i am doing a basic data logging system to see the frequency behavior of sound. What I did is to use the "acquire sound" system of Labview and connect a waveform graph to see the time-domain behavior of sound.

However, if I input a duration of 4 seconds (or any time), I will only see 75% of the sound (that is 3 seconds). I tried to extract the values using write to file to see if the waveform graph is the one who have the delay. however, the data also showed me 3seconds.

I will attach here the picture of the simple program i created.

I hope someone can explain to me why this happen.

I am using the soundcard and microphone of a laptop. I also tried using a computer microphone. I have tried this program to all computers I can use (2 laptops: SAMSUNG, ASUS, and one desktop computer core i5)