1) HALACHAH: WEARING A BAND-AID ON SHABBOS
OPINIONS: According to the Mishnah, it is forbidden to wrap a reed around a bruised finger on Shabbos unless it is wrapped for the Avodah in the Beis ha'Mikdash. Moreover, even in the Beis ha'Mikdash, it is forbidden to wrap a reed around a bruise in order to cause it to bleed (this was a common therapeutic practice). Such an act would involve a Melachah d'Oraisa, which is not permitted even for the sake of the Avodah (see Rashi DH Kan v'Kan).
May one wrap a bandage, or other protective covering, around a wound on Shabbos, or is such an act comparable to when one wraps a reed around a bruise, which is forbidden?
(a) The TOSFOS HA'ROSH notes that the Mishnah implies that it is forbidden to wrap anything around a bruise. Seemingly, one may not wrap a reed around a bruise due to a concern that he will wrap it tightly and cause himself to bleed, which is forbidden mid'Oraisa. If this is the reason for the prohibition, then this Mishnah is consistent with the other Mishnayos in this chapter, which prohibit one act in order to ensure that another act, which is mentioned at the end of the Mishnah, will not be done on Shabbos.
It follows that one is permitted to wrap a soft, wide piece of material around a bruise because such a fabric cannot cause the bruise to bleed, and thus there is no reason to prohibit its use. (HAGAHOS ASHIRI)
(b) The Tosfos ha'Rosh continues, however, and says that it is common practice to wrap a cloth around a bruise on Shabbos. Therefore, he concludes that the Mishnah is not concerned lest one tighten the reed to remove blood. Rather, the Mishnah prohibits reeds specifically because they have therapeutic properties, and it is prohibited mid'Rabanan to heal on Shabbos (this is also the approach of TOSFOS DH Lishma'inan). Any object which does not have such curative properties (such as a cloth or band-aid) may be wrapped on a bruise on Shabbos. This appears to be RASHI's opinion (103b, DH Korech) as well.
The TUR and REMA (OC 328:24) rule in accordance with the conclusion of the Rosh. (For the practical Halachah with regard to applying a band-aid on Shabbos, see Shemiras Shabbos Ke'Hilchasah 35:25.)
2) HALACHAH: MAKING NOISE ON SHABBOS
OPINIONS: The Gemara relates that when Ula heard someone knock on the door on Shabbos, he declared that the person desecrated Shabbos when he produced a loud noise. Rabah replied that noise on Shabbos is forbidden only when it musical.
What is the Halachah? Is one permitted to make non-melodious noise on Shabbos?
(a) TOSFOS (DH Hachi) cites the RIF and REBBI YEHUDAH BAR BARZILAI (the author of SEFER HA'ITIM) who rule that one is permitted to make non-musical noise on Shabbos. Although Ula prohibited any noise, the Halachah follows the view of Ameimar, who permitted non-melodious noise. Ameimar allowed the people of Mechuza to use a well with a pulley even though it made a considerable racket.
(b) RABEINU CHANANEL, however, rules that one may not cause noise on Shabbos, even if it is not musical. The MAHARAM (in a responsum cited by the HAGAHOS ASHIRI) suggests that Rabeinu Chananel prohibits noise only when one is interested in the sound that is produced (for example, a knock on a door in order to get the attention of those inside). If the noise is merely a by-product of another act (such as noise that emanates from a loose piece of metal jewelry), it is permitted. (See also SEFAS EMES.)
Although Ula prohibited the use of a noisy pulley to draw water from a well, there must have been some type of benefit gained from the squeak of the pulley. Alternatively, the pulley produced an especially loud noise which could be heard by many, and therefore it is prohibited to use such an object. (MAHARAM)
(a) The SHULCHAN ARUCH (OC 338:1) records the opinion of Tosfos and the Rif who rule that only musical noise may not be produced on Shabbos. The BI'UR HALACHAH writes that this is the common practice today.
(b) However, the VILNA GA'ON argues and maintains that the Halachah follows Ula (whose view is supported by the Yerushalmi). Therefore, one is not permitted to make noise on Shabbos unless the noise serves no purpose at all (as the Maharam writes; however, even the Vilna Ga'on permits the use of a noisy well-pulley, as the Bi'ur Halachah points out).
The Vilna Ga'on agrees that one is permitted to make noise in a manner that is "k'l'Achar Yad," that is, with a Shinuy. Accordingly, one may clap his hands with a Shinuy even to a musical beat (OC 339:3 and Bi'ur Halachah ibid.).
The REMA adds that one may not use a utensil that was made specifically to produce noise (such as a door-knocker) since one may be tempted to use the utensil to produce a musical beat (The Bi'ur Halachah, however, permits the use of such an object in extenuating circumstances, based on the ruling of the RAMBAM in Perush ha'Mishnayos.)
The MISHNAH BERURAH (338:2) points out that one may make non-musical and non-rhythmical noise with an object that is not made for making noise. For example, one may bang pots together in order to wake up a person.