Ginny is right. It's not the tubes but the chronic ear infections causing his speech problems. The tubes are the solution! His hearing has been muffled by all that fluid in his ears for so long and so frequently that he couldn't hear and process others' speech sounds properly. Children learn speech by listening, watching, and absorbing the speech around them. Once those tubes do their thing, he'll start picking up sounds and start talking soon. If nothing changes in a couple of months, go see a speech therapist.
As far as preventing ear infections, remember that the nose is connected to the ears by the Eustacian tube, and what goes up the nose can irritate the ears. Make sure that no one smokes in the house or no smokers go near him due to 1st, 2nd, and 3rd-hand smoke. Keep the air in the house clean of other kinds of air pollution, meaning no incense, no scented candles, no air fresheners, no smoke, no perfume, and limit exposure to fumes and household cleaners. Also, make sure that he's not laying down while drinking liquids to prevent liquids from going up the Eustacian tube. If he's got reflux, have him stay upright for 30 minutes after eating/drinking. Keep him away from sick kids/adults and treat his runny nose to keep mucus from going up there as well.
Best of luck to you!