The Mishna (Tamid 3,8) relates that the sound of the Sanctuary gates opening could be heard in Jericho - a distance of about 25 kilometers from Jerusalem! But it is not taught that this is because the sound was particularly clamorous or deafening. On a mystical level, they are connected, for they are the two cities in which the Israelites' conquest of the Land of Israel began and ended. Joshua entered into the Land through Jericho; it was necessary that he conquer Jericho first. David's conquest of the Jebusites who dwelled in Jerusalem was the action which completed the establishment of the Land of Israel as the seat of G-d's glory.
In addition to the sound of these gates opening, the Mishna also lists eight other sounds which were made in the Holy Temple and heard all the way in Jericho - including the muchni of Ben Katin, the sounds made by some of the musical instruments and the Levites' song, and the voice of the High Priest on the Day of Atonement. It is even recorded that the fragrance of the incense offering could be smelled in Jericho... and it caused goats in that locality to sneeze! (ibid.)
Although we are provided here with but an illusion, these passages have great depth of meaning. What occurred in the Holy Temple reverberated in Jericho, for on a spiritual plane, Jericho is the mirror image of Jerusalem and thus they are related in many ways. More importantly, Jericho is called "the lock of the Land of Israel" (Bamidbar Rabbah 15:15) and thus it was imperative for Joshua to enter through her and conquer her first. When one is strong, the other is weak, and when Israel's enemies are in possession of Jericho, it is impossible for Israel to be in full possession of her land (R. Zadok HaCohen of Lublin, Dover Tzedek 73:A).