When you're attempting to concentrate on a task at work and loud conversation is going on around you it becomes very difficult to focus. Some office environments call for a group participation type of culture where everyone is pitching in with everyone else's work. But many offices would rather their environments remain at a reasonable decibel level so everyone can do their work in peace. Inevitably there are those who break through the near silence and affect the atmosphere with loud talk. Unfortunately, this issue, if not taken care of, will only become more problematic and probably more disturbing.
Sensitivities between co-workers can be acute and if we don't handle the situation in the right way our request to lower the volume may be received defensively. First we need to evaluate how well we know the loud mouth. If we know the person well we may be able to make a direct request that they take their conversation elsewhere. It would be the simplest thing in the world to say "Could you please talk somewhere else?" or "Could you be more quiet?" and know that your comment will be received in good spirits.
If you aren't familiar with the loud talkers or they inhabit a different part of your office culture, i.e., a different department that you need to have open communication with on a business level, an alternative to a direct request is to speak to their department's administrative assistant if one if present. If you go directly to the loud mouths' boss you run the risk of being labeled a tattletale, another personality often shunned in offices. The administrative assistant can run interference for you to the talkers' boss. The boss in this scenario can then deliver the request as a general one naming no names as to who was offended by the loud talking. Often this can be handled with an email to everyone on the boss's staff rather than to the one offending individual.
In a situation with no administrative assistant you can always drop a hint to your boss as to how distracting these folks are. Your boss will no doubt ask questions and get all the facts straight and speak to the loud mouths' boss for you. Boss to boss isn't necessarily the best of the alternatives simply because it raises the issue to something that can only be handled by supervisors and this may be perceived as too extreme, but you may have no other choice.
A preliminary to reporting loud mouths to assistant or supervisor, and a way to have a little fun for yourself, is, from where you are sitting while the conversation is taking place, begin to join in or respond to what's being said. This is an alert that voices have grown so loud they are invading your space and, though the loud talkers may consider what they're saying to be private, they've opened up the conversation to you and anyone else within earshot of their voices. If they really don't want input from random listeners they may 'get it' that they are too loud and either remove themselves or quiet down.
Try to make your response as funny as possible. You may get laughter from workers in nearby cubicles who also are also disturbed by the loud mouths and have been waiting and hoping someone will do something. The laughter is another signal that you have support from the surrounding office community. Once the "private" conversation becomes public domain, it's amazing how quickly it will conclude and break up.
Remember there are always people within any office culture who will disturb others with loud conversation. If the volume is interfering with the work flow it needs to be addressed. However, we always should strive to be very intuitive about how to approach these situations because of the finesse required to maintain good working relationships.