Have you ever noticed a lump in your cat's throat when you pet him? Don't worry -- all cats have that. It's part of their larynx, i.e., their voice box. Male cats, like male humans, have larger larynges and, by extension, large, prominent Adam's apples.
At the top of all cat's windpipe is a hard structure. This is the larynx. When your cat meows, this is the part of the throat that's making the noise. As with humans, both male and female cats have this feature. Also, as with humans, male cats tend to be larger than females and have more pronounced larynges. This is why some male cats look like they have prominent Adam's apples -- it's because they do.
As your cat matures from a kitten to an adult, it's not unusual to see his Adam's apple getting bigger. If your cat's a long-haired breed, it might be hard to spot the neck lump, although a gentle pet should confirm its presence. Once your cat stops growing -- say a year and a half to two years after he's born -- his voice should normalize and the size of his larynx is unlikely to change. This physical feature is also involved in swallowing, coughing and vomiting. Naturally, both male and female cats need it. The only difference between the sexes is its relative size.
As your cat ages, you might notice his larynx getting even bigger. It's possible he has a slow-growing tumor in that region, i.e., larynx chondrosarcoma, or another throat disease. Larynx issues usually have similar symptoms, including sudden voice change, inability to make sounds, panting, open-mouthed breathing and general difficulty breathing. If you suspect something's amiss, schedule an appointment with your vet. If it's early enough, medicine may help. Surgery may be necessary, though, and could affect your cat's voice for the rest of his life.
Although the larynx is responsible for the majority of sounds your cat makes, there's one sound that remains a mystery. A cat's purr doesn't originate there; it's thought to come form adjacent false vocal chords. These structures don't usually protrude from your cat's throat, so there's no mistaking your feline friend's Adam's apple for another throaty feature. Still, they're in the general area, and, if you rest your hand on your cat's Adam's apple, you're likely to feel vibration there when he's purring.