People often have dogs as deterrents against burglary. Large dogs, however, tend to eat a lot.
Today’s invention offers a way to achieve the deterrence which a large dog provides, if you only have a tiny terrier.
It consists of a neck-mounted loudspeaker which boosts the bark volume of a small dog, whilst also lowering the frequencies associated with its yapping.
(This would probably require a loudspeaker horn, so that the noise would project forward so as to not scare the dog with its own bark).