If you enjoy your peace and quiet, then you probably don't love being around an unfixed male cat -- especially during the night. When tomcats smell the presence of a female cat in heat, the loud, piercing and persistent vocalization begins -- much to the dismay of surrounding ears.
When a tomcat smells a female cat who is ready and available to mate, he will, understandably, begin to "call out" to her. Essentially, he tries to highlight his existence to her for mating purposes. You may notice a male cat meowing and yowling with frequency and urgency. These vocalization behaviors are especially prevalent from the evening on, so keep your ears covered.
To make matters more chaotic -- and noisy -- female cats also vocalize out to males. When queen cats are in the midst of their heat cycles, they also try to promote their mating readiness to males. Like with tomcats, the yowling sounds are often persistent and loud -- and usually nocturnal too, though not always. The difference is female cats usually only vocalize every few weeks or so, due to heat. Male cats generally make sounds any time they sense the presence of a nearby female!
If a male cat has easy access to the outdoors, he will often spend his days roaming around the area in search of available females. This wandering behavior tends to be accompanied by loud vocalizations. Apart from the cacophony of sounds, tomcats also engage in a variety of other mating behaviors when they are ready, including territorial urine marking, restless pacing and even aggressive fighting with competitive males.
If you own a tomcat, neutering him is a sensible, responsible, compassionate and peaceful option. Cat overpopulation is already an overwhelming problem all around the world. Once you neuter a cat, he is unable to father kittens, and therefore unable to contribute to the problem -- phew. Not to mention, the procedure usually puts an abrupt end to disruptive and frustrating mating behavioral patterns, including loud sounds, wandering off, fighting and even icky urine spraying. Not only will you be able to sleep better, but so will the rest of the citizens in your community!