Al gegoogled? Lijkt een Hytera eigenschap te zijn. Weerstandje over de LS doet wonderen
https://www.m0lmk.co.uk/2019/05/06/hytera-pd-md785-waterfall-noise/The PD785 is a little more difficult as it has less room and the speaker is attached with a flat ribbon cable. You need to remove the case screws (2 on the back and one on each side) and remove the castle nuts from the antenna connector, volume and channel selectors.
Then you can remove the radio chassis and install the resistor on the speaker. I tried several and settled for 120 Ohms. I also placed a small piece of insulation tape over the area where the resistor connected to the ribbon cable.
Vooral voor de mobiele versie ervan komt het voor,
https://www.hamdigitaal.nl/2015/10/ruisonderdrukking-md785/[mod: onnodig lange YouTube-link aangepast]