A MELLOW booming travels to us on the cold air. Donandy, Paul, and I have just shared Coca-Cola and bratwurst and mustard on a roll, standing in our overcoats and scarves at the Christkindlmarkt food stand on the Kaufingerstrasse. Shoppers hurry past us. Others like ourselves amble along, moving as if called toward the music on the Marienplatz.Saturday we heard a choir sing as its members stood on the steps of the Dom in Salzburg. It was raining then and we took shelter in the cathedral entrance. We stood behind the choir, looking past the singing figures to the moving, weaving, bobbing umbrellas. Later we heard the same sweet booming music we hear now; it was blown to us from a rooftop, a balcony, and a room in a clock tower. Now we know it is horns. It is about noon on Monday, Christmas Eve. We move into the Marienplatz. We search over the rooftops of the Christkindlmarkt booths - they sell ornaments, figurines, candy, and sweets - and look for the horn players below the dancing figures in the Rathaus clock. Ah! There they are on a balcony: a French horn, two cornets and a trombone. Four men in overcoats and Bavarian hats, gloves stuffed into their coat pockets as they finger the keys to make their music. Errand-runners push past us; they seem not even to hear the music. We crowd back against the glass wall of the Benetton store and watch the musicians. We do not recognize their selection. Still it is lovely. Wanting to get closer, we stride across the flow of passersby, move between the booths and enter a group of people gazing up at the horn players. Now the music ends. We and the crowd around us offer muted applause, gloved hands beating hollowly against one another. One of the cornet players, an older man, perhaps the leader, raises his hat to us. The French horn player beside him, taller, younger, grins down shyly. Alone in his own world, the trombone player shakes his instrument sharply. A TV crew climbs out onto the balcony; it records close-ups of the musicians, then pans down onto the audience. Nearby the Fischbrunner splashes merrily away as if it made perfect sense for stone fish to frolic in a fountain on an early winter day. The air feels as if it will snow before nightfall. It is a curiously specific moment: Munich, Christmas Eve, Christkindlmarkt, the unfamiliar carols, the files of unhearing shoppers hurrying through the listening crowd, the music makers above us, acknowledging us with waves. And, of course, a TV crew recording the sound, preparing it for audiences who will chat, eat, and do the dishes through it, for listeners who will not listen to it, for viewers who will not see it even as they watch it. A specific moment which carries no specific emotion. Just Christ mas Eve day passing our way in an unfamiliar place. Then the players once more raise the horns to their lips. Their music starts once again. The notes ring out: "Silent Night, Holy Night." The first time through, shoppers move past us. The bustle continues. The second time, the horns play softly. The bustle subsides. A curious thing happens to the air. A hush falls across it. It is the hush you feel just before snow. And in the hushed stillness the cold seems to touch us with a warmth. The people around us begin softly to sing: "Stille Nacht, heilige Nacht! Alles schlft, einsam wacht nur das traute, heilige Paar." The notes drop down upon us as gently as snow. The third time through those offering the notes become one with those receiving them. We are all making music now: The horn players playing, most of those around us singing the carol in German, the rest of us humming the tune. The three of us are no longer travelers from California, a man, a woman, and their 18-year-old son here in Munich to spend Christmas with friends. Now the three of us are merely members of the group of humanity collected here. We are all together in this brief moment of warmth in coldness, of brotherhood among strangers as "Silent Night, Holy Night" enfolds us in the music-snow of this noontide.