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Bears usually do not vocalize, unlike bears in movies with dubbed-in soundtracks. When the need arises, they communicate with grunts, by expelling air in different ways, or with a resonant "voice". Black bears use the same vocalizations and body languages toward people that they do toward each other, and knowing those can help people react to bears they encounter.
The most common bears sounds are grunts, which are used in amicable situations as when vocalizing to play partners, mates, cubs, and occasionally people. The sound most often heard by people is a loud blowing, which means a black bear is nervous or afraid. Campers and hikers hear this when bears retreat or bluff. Three types of bluffs are common, and all include sudden, explosive blowing. The most common is blowing with clacking teeth- the defensive display of a scared bear. Another display is blowing with a short lunge and slapping the ground or an object- any uneasy black bear's way of saying "Move back."
The black bear's resonant "voice" is reserved for strong emotions and is seldom used except by cubs. Cubs readily scream in distress, whine when approaching their mother, or give a tremulous hum when nursing or comfortably warm. Adults (and cubs) use their "voices" when in pain (bawling), in fear (moaning), in combat (bellowing), or when seriously threatening (deep-throated pulsing sound). Unlike cats and dogs, black bears seldom, if ever, growl, although the fear-moans of treed or trapped bears are often mistaken for growls. Predacious attacks are silent, as is normal feeding.