I want to remove Echo and Noise, but didn't success

This is my code:

NSArray *mandatoryConstraints = @[
                 [[RTCPair alloc] initWithKey:@"OfferToReceiveAudio" value:@"true"],
                 [[RTCPair alloc] initWithKey:@"OfferToReceiveVideo" value:@"true"],
                 [[RTCPair alloc] initWithKey:@"googNoiseSuppression" value:@"true"],
                 [[RTCPair alloc] initWithKey:@"googEchoCancellation" value:@"true"]
];

Please tell me the solution.
Thanks!