One of the Shofar sounds is called the "Shebarim," and consists of three brief sounds. It is the same as the long, straight Teki’a sound, only shorter, and three such sounds are blown consecutively. (Listen to audio recording to hear a simulated Shebarim sound.) The Toke’a (person who blows the Shofar in the synagogue) must ensure to blow all three sounds in a single breath. He may not stop to take a breath in between any two sounds of the Shebarim. If he did stop to take a breath, then the sound is invalid and the Shebarim must be repeated. The Toke’a should make a slight pause in between the blasts of the Shebarim, so it does not sound as one elongated blast, but he must ensure to produce all three sounds in a single breath.
The Arizal (Rav Yishak Luria of Safed, 1534-1572), as mentioned in Sha’ar Ha’kavanot, taught the Kavanot (intentions) that one should have during the various sets of Shofar sounds. He said that during the Teki’ot Di’meyushab, the thirty Shofar sounds blown before Musaf, one should have in mind that the sounds should negate the Yeser Ha’ra of idolatry. One should also have in mind to repent for any sins he may have committed involving idolatry, which includes anger, as the Gemara teaches that anger is similar to idol worship. During the Shofar sounds blown during the silent Amida, the Arizal said, we should have in mind to negate the Yeser Ha’ra of Arayot (immorality) and to repent for any wrongs committed in this area. When the Shofar is blown during the repetition of the Amida, one should have in mind all sins related to murder, which include publicly embarrassing people, which is deemed equivalent to murder. Finally, while the final ten sounds are blown during the Kaddish Titkabal at the end of Musaf, one should have in mind that these sounds should negate the Yeser Ha’ra to speak negatively about other people (Lashon Ha’ra).
Besides instructing us of what to think about during the Shofar blasts, the Arizal’s teaching also alerts us to the severity of the sin of Lashon Ha’ra, as an entire series of Shofar blasts is needed in order to atone for this sin and to reduce the desire to engage in it. In this sense, it is parallel to the three grievous transgressions of idolatry, immorality and murder. Indeed, the Gemara attributes the destruction of the First Temple to these three sins, and the destruction of the Second Temple to Sin’at Hinam (baseless hatred), which involved Lashon Ha’ra. The Gemara concludes on this basis that "Lashon Ha’ra Ke’neged Kulam" – the severity of speaking negatively about other people is equivalent to that of the three cardinal sins combined. It thus comes as no surprise that we require a special section devoted to atoning for, and curbing the urge to engage in, Lashon Ha’ra.
Summary: The one who blows the Shofar should make a slight pause between the short blasts of the Shebarim sound, but must not take a breath between the sounds. While hearing the Shofar blasts before Musaf, one should have in mind to atone for sins involving idolatry; during the Shofar blasts blown in the silent Amida, one should have in mind to atone for sins involving immorality; during the Shofar blasts blown in the repetition of the Amida, one should have in mind to atone for sins involving murder; and during the final Shofar blasts blown after Musaf, one should have in mind to atone for sins involving Lashon Ha’ra.