Some have hypothesized that the time of an "uh" or "um" is used for the planning of future words; other researchers have suggested that they are actually to be understood as full-fledged function words rather than accidents, indicating a delay of variable time in which the speaker wishes to pause without voluntarily yielding control of the dialogue. There is some debate as to whether to consider them a form of noise or as a meaning-filled part of language. Speech disfluencies have also become important in recent years with the advent of speech-to-text programs and other attempts at enabling computers to make sense of human speech. "Hmm"
Hmm is an exclamation (an emphatic interjection) typically used to express reflection, uncertainty,  thoughtful absorption, or hesitation. Hmm is technically categorized as an interjection, like um, huh, ouch, erm, and wow. The first h-sound is a mimic for breathing out, and the second m-sound, since the mouth is closed, is representing that the person is not currently sure what to say ("erm" and "um" are used similarly). The pause filler indicates that the person is temporarily speechless, but still engaged in thought. The variety of tones, pitches, and lengths used add nuances in meaning. Etymology
The expression is used in many different languages, however the origin of "hmm" is difficult to find, mainly because "the word is so natural that it may have arisen at any time," as highlighted by linguist at the University of Minnesota and an expert on word origins, Anatoly Liberman.
One of the most common locations for a foreign body is the alimentary tract. It is possible for foreign bodies to enter the from the mouth, or from the rectum.The objects most commonly swallowed by children are coins. Meat impaction, resulting in esophageal food bolus obstruction is more common in adults. Swallowed objects are more likely to lodge in the esophagus or stomach than in the pharynx or duodenum. Diagnosis
If the person who swallowed the foreign body is doing well, usually an x-ray image will be taken which will show any metal objects, and this will be repeated a few days later to confirm that the object has passed all the way through the digestive system. Also it needs to be confirmed that the object is not stuck in the airways, in the bronchial tree. Treatment
Most objects that are swallowed will, if they have passed the pharynx, pass all the way through the gastrointestinal tract unaided. However, sometimes an object becomes arrested (usually in the terminal ileum or the rectum) or a sharp object penetrates the bowel wall.