Whistling sound

Good markets for everyone. My car peugeot 307 2007 model 1.6 petrol and 3 years lpg fitted and automatic gearbox at 108.000 km. My problem is that the car has been making a whistling sound in the period of 2000 revolutions for the last 1 week. The sound increases when I press each gas, and the sound stops when I pull my foot from the gas. I especially noticed that there is no different sound from the engine other than normal operation. What should I do now, how should I proceed, I expect an answer from my brothers. Good day to everyone

If there is a turbo in his vehicle, he does. All of the turbos give a whistling sound :)

There is no turbo in the car :) I got the sound system last week.

It is likely that it comes from exhaust.

the problem is resolved. My problem is that the amplifier gives the sound coming from the engine directly to the speaker. I eliminated the sound with the anti-interference filter.