Window air conditioners get noisier as they age.
Causes: loosening of fasteners, aging of gaskets, wear and tear of the compressor, fan, dust, debris -------- and so on.
Check the cause, make corresponding countermeasures, comprehensive maintenance, the noise will be reduced.
Silencer is not desirable, imagine, if feasible, professional developers, why invest a lot of manpower and resources, research and development of split air conditioning? And from the installation, cost, maintenance and other aspects of the split air conditioning are not advantageous?