Talmud for Rosh Hashanah 66:3

⁶⁴Sifra Emor Parashah 11(7), Behar Parashah 2(4); Babli 33b/34a.“From where that there is a single sound preceding? The verse says, you shall convey the shofar. And from where that there is a single sound afterwards, the verse says, you shall convey the shofar⁶⁵Lev. 25:9 reads: You shall convey the shofar of sounds in the seventh month, on the tenth of the month; on the Day of Atonement you shall convey the shofar in all of your land. It seems that they interpret “convey” as conveying a single sound.. So far the Jubilee, New Year’s day? You shall convey the shofar of sounds in the seventh month, on the tenth of the month, on the Day of Atonement. The verse did not have to say, in the seventh month. Why did the verse say, in the seventh month? Only that everything you are doing in the Seventh Month do as on the Tenth of the Month. Since here he blows, modulates, and blows, so also there he blows, modulates, and blows.”