Can't change DSP update period(FMOD 2.03)

Hi there,I try to reduce the DSP update period in unity,so i used a callback to handle it:

public override void PreInitialize(FMOD.Studio.System studioSystem, Action<FMOD.RESULT, string> reportResult)
    {
        studioSystem.getAdvancedSettings(out ADVANCEDSETTINGS settings);
        settings.studioupdateperiod = 5;
        Debug.Log(studioSystem.setAdvancedSettings(settings));
    }

I changed DSP buffer size to 128 to ensure to reduce latency,but when i measured the update period using getTimelinePosition(out time),the latency still remains at 10ms.
If fmod for unity have a default minimum latency so I can’t continue to reduce it?