The sound recalled an image in Don Quixote's mind of men beaten brutally with chains, by their captors who hold them for no greater charge than crossing paths with such ferocious animals.
With the tip of his helmet and the unsheathing of his sword, Don Quixote spurred the aged Rocinante towards the valley and the cries bellow. Sancho looked on as he had been doing for the previous few minutes. Still unable to decipher the look on the face of his friend, he made sure his proud steed was fully hydrated, and slowly followed the dust trail left by the hasty departure of the great Don Quixote.
As Don Quixote emerged through the passage he had found in the vast blackberry bramble, he discovered a scene unlike the one he had envisioned atop the hill. Before him were three men and one woman. Throwing what Don Quixote could only guess to be long distance weaponry at steel mannequins with chains in place of the human rib cage. Our hero knew better, after many unnecessary injuries to himself and his dutiful squire, than to ride directly into the line of fire in this shooting range. Instead he chose to watch on and examine the purpose of this training. He saw right away that the discs being thrown were made with blunt rounded edges and would probably be outfitted with blades to fulfill the sinister desires of its thrower. After all four assassins had buried their weapons into the midsection of their target, they congratulated one another and set out to commit the same foul deed on another unsuspecting herdsman (who else would be standing alone on a hillside in the high mountains). Don Quixote saw his window in the wall of thrown weapons and prepared to attack. Having lowered his face protection and adjusted the grip on his sword, Don Quixote was now prepared to rid the Earth of this evil training facility and all of its inhabitants. Like all knights errant, Don Quixote took an oath to right any wrong he observed without regard to his own health and safety.
It was Sancho Panza who disliked this part of the oath most. If only his role as squire to the Knight-of-the-sand-countenance was to persuade him to keep free of bodily harm, than Sancho would have been much more readily available to perform his duties; instead of meandering down the path in search of a safe place to assess his master's injuries. It was at this moment of thought that Sancho realized what Don Quixote was about to do. He is going to slay this gypsy band and Sancho would rightfully inherit any gold or jewels left as bounty (Don Quixote must never benefit financially from any of his deeds or he would be in direct defience of his oath sworn before the squire Sancho Panza). At this realization, Sancho had the most confidence in the great knight, and decided to rest in the meadow just above the gypsy camp.
From this perspective, Sancho could see Don Quixote's mistake clearly before Don Quixote could possibly have realized it. Amongst the assassins there were three dogs. All of which could encircle and take down a horse the size and health of Rocinante. Upon reaching the dogs, Don Quixote pulled on the reigns hard to make Rocinante lift his front hooves and use a stomping motion to keep the dogs at bay. The dogs barked a prodigious amount and Rocinante could not handle the racket. Don Quixote retreated the attack long before he reached his targets.
At the site of this, Sancho felt great shame for wishing the deaths of the gypsies and decided to congratulate Don Quixote on his decision to keep safe his steed and only mode of transportation and allow the gypsies, who have already begun to leave after seeing the drawn sword and battle pose of the knight before being discovered by the dogs, to go free. Don Quixote saw no shame in surviving his horse and thanked Sancho for his reassurance, reminding him that if the dogs had not attacked Rocinante, those gypsy assassins would not live a moment longer to plan attacks on lonely herdsmen.
So it was agreed to take a high path through the mountains and seek adventure and righteousness elsewhere.