16 year old cat yowling -- started a few months ago

Question
Our 16 year old cat suddenly started "yowling" for no apparent reason.  When I get his attention he looks at me and mews quietly but he'll be sitting in site of us and start this unbelievable yowl.  So loud we can hardly belief it's coming out of him.  He does it at various times and often gets down out of our bed at night and stands there and yowls.  He also does it during the day for no apparent reason.  He's driving us crazy.  Is there any way to stop this?  Is it old age?  He's been tested for hyperthyroidism and it's negative but he drinks lots of water, occasionally vomits, but so far still uses the litter box.  Any help you can give will be appreciated.  We also have a 3 year old cat but they get along fine together so I don't think that's a problem.

Answer
B. Kapp.

At age 16 your cat is geriatric. So, there could be a number of things going on.  Remember I am not a vet, so, I would have a complete physical done by your vet.  I would be a bit concerned by the water intake as this can often be a harbinger of kidney, bladder, or other urinary tract problems.  I wonder if he may be getting some pain or discomfort at times, unbeknownst to you, which may bring on these episodes.

In my experience, if it is not an obvious health issue, there is nothing I know that can stop your cat from yowling. What I do suggest is to pick up a set of airline ear plugs (for trans oceanic flights).  These are soft, comfortable and very effective and should be available from most travel stores. I am not suggesting this tongue in cheek, they really do work.

Best regards... Norm