The answer to 'air duct sealing making noise' is that air duct sealing can sometimes cause noises like whistling, rattling, or banging. This is usually due to improper installation or the use of the wrong type of sealant material. Improperly sealed ducts can create air pockets or turbulence that leads to these noises.
In most cases, the solution is to have a professional HVAC technician re-seal the ducts using the proper materials and techniques. DIY duct sealing is possible, but it requires careful attention to detail to avoid these types of problems. If you're not comfortable with the process, it's best to call in an expert to ensure the job is done right and your ducts are sealed effectively.