There are many causes for hiccups.
If you are acid reflux sufferer, the constant regurgitating (backing up) of the liquid content of the stomach into the esophagus, can lead to chronic pharyngitis (inflammation of your throat).
Pharyngitis causes irritation of the pharyngeal branches of the vagus nerve (responsible for innervation of diaphragm) or the recurrent laryngeal nerve, resulting in hiccups.
Hiccups are the result of diaphragm spasms or contractions.

Hope I helped!
Have a good, healthy day!
Marija