A teki’a is a long, smooth sound which must be at least as long as a teru’a. But we blow three types of teru’ot: shevarim-teru’a, shevarim, and teru’a. The halakha mandates that within each set of blasts, the teki’a must be the length of the teru’a of that set. Therefore, when tashrat is blown, the teki’a must be the length of eighteen tromitin, as a shevarim is about nine tromitin and the length of the teru’a is nine tromitin. Even if someone extends the teru’a or blows additional teru’ot, the teki’a does not have to extend beyond eighteen tromitin, as everyone agrees that this length fulfills the obligation. When blowing tashat or tarat, the teki’a must be the length of nine tromitin, as both the shevarim and the teru’a on their own are nine tromitin long.
As we have said, a tromit is a short blast of the shofar. The combination of many short blasts makes a teru’a. How long this takes depends upon the shofar-blower and the shofar. The faster ones blow nine tromitin in 1.25 seconds, while the slower ones take 2.5 seconds. Each shofar-blower must calibrate his teki’a and shevarim based on the length of his tromitin. If one wishes to meet the criteria of all the opinions, he should take five seconds to blow tashrat and 2.5 seconds to blow tashat and tarat.
Even if the quality of the sound changes several times during one teki’a, as long as the teki’a is continuous, it is acceptable, as any type of blast is acceptable. Those who are meticulous try to blow stable, continuous notes with no rises, falls, or other variations.
. Shulḥan Arukh describes tromitin as the shortest sounds possible, made with minimal effort (590:3). Yet not everyone’s tromitin are equal. Expert shofar-blowers can blow nine tromitin in 1.25 seconds, while it takes 2.5 seconds for slower blowers. The teki’a and shevarim must always correspond to the teru’a. In any case, even for the slower blowers, in a set of tashrat, as long as each teki’a is at least 2.5 seconds it is good enough, as be-di’avad 3 tromitin are adequate for a teru’a and 6 tromitin for a shevarim. In the sets of tashat and tarat, be-di’avad a teki’a of 1.5 seconds’ duration suffices.
. “All shofar sounds are acceptable” (Rosh Ha-shana 27b; SA 586:6). This means that even if in the middle of a teki’a the sound changes, it is acceptable, as long as it is continuous. True, some interpret Ritva (33b) as saying that the sound may not change. But in fact, he simply writes that one should not intentionally insert a rise at the end of the teki’a. Indeed, some who are meticulous avoid rises in the teki’a (R. Ḥarlap). However, technically, such an irregularity does not disqualify the blast. (This is the position of all the poskim, and R. Shlomo Zalman Auerbach rules this way in Halikhot Shlomo 2:9.) Nevertheless, it would seem that if a teki’a rises or goes up and down repeatedly, so much so that it mimics a shevarim, it is proper to redo it.
Yemenites traditionally incorporate a rise in tone at the end of a teki’a. During the teki’a this rise expresses the heights of joy, while during the teru’a it expresses the depths of sorrow. Those who follow the Yemenite practice must ensure that there is a clear difference between the teki’a and the teru’a, making the teki’a very stable and the teru’a truly tremolo. The shofar-blower must be meticulous not to waver while blowing the teki’a, lest it sound like there is a teru’a in the middle of the teki’a.