Midrasz do Liczb 10:5

(Bamidbar 10:5) "And you shall sound a blast" ("Utekatem teruah"): A teruah (a rapid succession of three notes, tremolo) by itself, and tekiah (a long, sustained sound) by itself. You say, a tekiah by itself and a teruah by itself. But perhaps (in this context) tekiah and teruah are one and the same? (This cannot be, for) (7) "And when the people are to be gathered, you shall sound a tekiah and not a teruah" indicates that tekiah and teruah are distinct sounds. "utekatem teruah": We are hereby taught that a tekiah precedes a teruah. Whence is it derived that a teruah (also) follows a teruah? From (Ibid. 6) :"teruah yitkeu" ("a teruah shall they blow.") R. Yishmael the son of R. Yochanan b. Beroka says: This (derivation) is not needed. It is written (Ibid.) "And when you blow a second teruah." Let "second" not be written. Why is it written? To serve as a prototype (binyan av) for the tekiah, that it be second (i.e., after) the teruah — whence we learn that (in sum he blows) tekiah-teruah-tekiah. This tells me only of (the order in) the desert. Whence do I derive (the same for the order on) Rosh Hashanah? It is written "teruah" here and it is written "teruah" elsewhere (re Rosh Hashanah). Just as "teruah" here — tekiah-teruah-tekiah, so, "teruah" there — tekiah-teruah-tekiah. Three "teruoth" are written in respect to Rosh Hashanah: (Vayikra 23:24) "Shabbaton zichron teruah," (Ibid. 25:9) "Veha'avarta shofar teruah," (Bamidbar 29:1) "Yom teruah yihiyeh lachem" — two tekioth for each (teruah). In sum, on Rosh Hashanah there are three teruoth and six tekioth — two (sets of tekiah-teruah-tekiah) prescribed by the Torah, and one by the scribes: "Shabbaton zichron teruah," "veha'avarta shofar teruah" — by the Torah. "Yom teruah yihiyeh lachem" — This comes for its teaching (that the shofar is blown in the daytime ["yom"], and not at night). R. Shmuel b. Nachmani says in the name of R. Yonathan: One prescribed by the Torah; two prescribed by the scribes. "Shabbaton zichron teruah" — by the Torah. "veha'avarta shofar teruah" and "yom teruah yihiyeh lachem" — These come for their teachings, ("veha'avarta") to teach that there is an unbroken sound (tekiah) before the teruah, and "yom," to teach that the shofar is blown in the daytime.

(Bamidbar 10:5) "And when you blow a teruah, then there shall travel the eastern encampments. (6) And when you blow a second teruah, then there shall travel the southern encampments": Perhaps just as he blows (tekiah-teruah-tekiah [separately]) for the eastern and southern (encampments), thus does he blow (them separately) for the northern and western encampments. It is, therefore, (to negate this) written "a teruah (i.e., tekiah-teruah-tekiah) shall they blow for their travels" — one tekiah (i.e., one set tekiah-teruah-tekiah) for two sides (together, the northern and the western). Other say: (The meaning is) three (i.e., three blowings, tekiah-teruah-tekiah) for each side (northern and western individually).