All-on-Fours clacking when speaking

Normally, this is a situation when both arches are made from zirconia, as they are the same material and make a distinct noise when they meet. Sometimes, some minor contouring in specific spots can help, but often it only alters the sound and doesn't' eliminate it. Other options are to make one arch zirconia and the other made out of a different material (usually PMMA). Another option is to have an arch made in a method that labs call "thimble", where there is a metal frame that is designed to have projections where each tooth is, and then individual crowns made for each tooth. This seems to dissipate the noises somehow and is also repairable in the future (should a tooth chip or break). ALL of these options (minus the contouring option) require remaking one or both arches and will incur a significant cost.

Everything sounds normal; however, the placement of your implants may be a touch off. As your mouth heals the swelling will decrease and this will help with your speech.  One thing I tell my patients is to sing out loud to music or practice by reading out loud. Also, typically, the temporary set of teeth is heavier than the final set. Does your dentist offer XircOn Ultra teeth? They are the newest technology made of the new nano-ceramic hybrid material, making them a lot lighter than Zirconia and much stronger than acrylic. 
With all of this said, you should be happy with your teeth, even if they are temporaries. You after all are the one who has to eat, speak, and live with them for a couple of months. Therefore, they should be functional and aesthetically pleasing. Go to your dentist and ask for them to fix them. Just my 2 cents.

Question: Did a prosthodontist place your dental implants? If not, you should make an appointment to see one to make sure your implants were placed correctly. 

Hi and thank you for your question. The clacking sounds has  to do with the position of you teeth, but remember that you are in a transition stage, since you are now wearing temporary dentures. This temporary dentures can be adjusted to correct some minor issues. The pronunciation of certain words is something that takes time to get adjusted to, as your soft tissues heal the swelling will fade leaving spaces in between the gum and the denture, sometimes this will lead to the passage of air under the denture, therefore the problem with pronunciation. Temporary dentures are also bulkier than the final dentures, this will cause the tongue to be in a different position changing your speech, with time this will get better. I would visit a Prosthodontist (specialist in dentures, crowns and implant restorations) to evaluate your case.
Good Luck to you!!
Dr. Juan C. Arroyo
Oral and Maxillofacial Surgeon