The vehicle in question is a 2009 Kia Sorento with a 2.5 litre common rail direct injection (CDI) engine.

[Thenornpo]

The turbo emits a noise at around 1500 rpm, without any visible smoke, and the vehicle performs adequately on the road. It would be beneficial to determine the cause of this siren-like noise.
If I apply little pressure on the accelerator pedal while driving, the performance is satisfactory. Similarly, once the vehicle reaches a certain speed, the performance remains satisfactory.

[Jollyno]

A 'police siren' noise from a turbo may be caused by blade damage resulting from a foreign item entering the engine or exhaust manifold.

[Thenornpo]

Thank you for that, it is really appreciated. The potential issue might be an imbalance caused by carbon accumulation on the blades. It is likely necessary to remove for examination. It ceased for an extended duration and then resumed.

[Jollyno]

The Qashqai vehicle belonging to our neighbours emitted a siren-like sound from the turbocharger. He brought it to a nearby expert who discovered that several of the blades were impaired. The turbo was fixed, and the oil feed lines and hoses were replaced. The current environment is tranquil and devoid of noise. 🙂

[Thenornpo]

Indeed, I am considering the possibility that there may be a limitation in the oil supply to the shaft, resulting in insufficient lubrication. I will thoroughly examine all components to verify this hypothesis.

[Cincoon]

Have you inspected the hoses connected to the turbocharger for any loose clips? These objects will produce a shrill sound.

[Thenornpo]

Tomorrow, I will thoroughly examine the situation, with the expectation that it is only a question of inspecting and ruling out any grounds of concern.
Thank you so much for your assistance; it is really motivating.