I am not an acoustics expert, but I understand that if we can hear the pure tone click sound at 'I' equals 1, then it should be possible to adjust its value to get the desired output of 5 dB.
Your calculation for 'I' (3.1e-12) is correct to achieve 5 dB in theory, but in practice, you might not hear it because the actual output depends on a multitude of factors like the speakers' frequency response, its impedance, the computer's audio gain settings etc.
To get closer to the desired 5 dB output, you’ll need to measure the actual sound level using a dB meter. Start with an audible 'I' value, play the sound, and adjust 'I' incrementally while monitoring the output with the meter. I am not sure how well the meter will handle short clicks, but the idea is using some form of audio sensing to measure the output amplitude. This will compensate for real-world variables like your hardware setup and the system audio settings.
