This is on an app called OTOTETSU, which is available free on the App Store. It simulates the waveforms generated by VVVF inverters and sounds you hear from 3-phase AC traction motors. 3-phase does not refer to the sounds you hear, they refer to the type of AC power that the motor uses according to the polyphase system. You will have to know the gear ratio, wheel diameter, type of inverter, acceleration and deceleration rates, add number of poles the motor has before you can simulate these PWM patterns. The links are in the description.
@@METRO_SUBWAY It usually would only work if you have an inductor recording, but for the Tube, I just had to listen to the train carefully as it leaves the station, then figure out its pulse pattern, which (this video was made before I knew it was the following) is: A(1kHz)→15P. The 2009 stock doesn't have random with modulation on either mode.