One of the first chassidim who came to Lubavitch after the Mitteler Rebbe settled there in תקע"ג (1813) was the eminent chossid, Reb Hillel Paritcher. The Mitteler Rebbe had instructed his chassidim that whenever they were traveling home, they should stay over in every town through which they passed, and chazer a maamar that they had recently heard.
Once, when Reb Hillel was about to return home, he asked the Rebbe what he should do about this directive, because the villagers whom he would meet on his way were simple folk who could not grasp the abstract concepts of Chassidus.
The Rebbe went into deep thought for a moment and then assured him, Di neshama hert – “The teachings of Chassidus are heard by the neshama, which is identical in everyone. Those words then trickle down into the body and give the listener the strength to fulfill the 248 mitzvos-aseh, and to abstain from transgressing the 365 mitzvos lo-sa'aseh."
(אג"ק הריי"צ ח"ג ע' שלא, היום יום כד אדר א')
Upon seeing his younger colleague, Rebbi Yehoshua ben Chananya, the tanna Rebbi Dosa exclaimed, “I remember that when he was an infant, his mother would take him in his carriage to the beis midrash so that his ears would absorb the words of Torah!"
(תלמוד ירושלמי יבמות פ"א ה"ו)
The Rebbe often mentioned that mothers used to rock their little ones to sleep with rhyming lullabies of Yiddishe content, such as “Torah iz di beste sechorah” (Torah is the best merchandise). The Rebbe said, “Some people think that it makes no difference what one sings to a young child, since anyway he does not understand. The truth is that everything that enters a child's ears affects his neshama in the years ahead.” A mother must therefore not only know about the importance of Torah: she should sing about it to her child.
(שיחו"ק תשל"ט ח"א ע' 616, תשל"ז ח"א ע' 112)
Hearing Only Good
Rabbeinu Yonah writes that just as speaking indecently harms a Yid's neshama, so too listening to indecent talk tarnishes one's neshama. The Shaloh writes that a child who hears goyishe songs will develop a negative nature.
(ס' היראה לרבינו יונה, [שבת נט ע"א], משנ"ב סי' תקס שעה"צ כה)
The Tzemach Tzedek said, “The bell in Petersburg brought forgetfulness upon me.” Until he visited Petersburg in the year תר"ג (1843), he forgot nothing, but hearing the church bells caused him to forget.
(לקוטי סיפורים ע' קלח)
Imagine the surprise of the talmid who entered the home of the Chasam Sofer and found him with his fingers in his ears. He stood perplexed until the Chasam Sofer asked him, “Is it still chiming?" He then understood that his mentor wanted to avoid hearing the sound of the bells.
(קדושת עיניים ע' 331)
Reb Nachman of Breslov, said that hearing a rasha speak has a negative influence on the listener.
(לקוטי עצות דיבור סק"ח)
When a certain chossid complained that he was having doubts in emunah, the Rebbe instructed him to discontinue setting his clock by the chimes of the local church.
(כפר חב"ד 672 ע' 20)
Protecting Oneself
HaShem created man's fingertips narrow enough to enable him to obstruct his ears from hearing improper things. The soft earlobe was created for the same purpose.
(כתובות ח ע"ב)
The Rebbe points out that unlike the other senses, hearing does not require the cooperation of the listener. One will hear a nearby conversation unless he makes an effort to avoid hearing it.
(תו"מ תשמ"ח ח"ד ע' 15)
Reb Shlomo Leib of Linchna, a student of the Chozeh of Lublin and the Yid HaKadosh of Pshischa, made every effort not to listen to unsuitable talk, and for his part, he was careful to speak only when necessary. When he was young, he rented a room together with some others in the home of a tailor, but would always return there only after they had already gone to sleep.
It once happened that the beis midrash closed earlier than usual, and as Reb Shlomo neared his boarding home, he noticed that the tailor was still wide awake and was sitting and joking with his friends. True to his principle, he kept at a distance, but due to the freezing temperature, he walked to and fro to keep himself warm. This did not help much, but he refused to go inside, though he knew this might cost him his life. With the help of HaShem, the lamp suddenly went out, and the renters retired for the night. Only then did Reb Shlomo go inside.
"From then on, in order to avoid such a situation again,” he later said, “I learned to give myself a forewarning, by honing my listening abilities and being able to hear whispering even at a distance."
(סיפורי חסידים זוין תורה ע' 488)
The Rebbe Rashab once mentioned that he had lost his hearing in one ear. Seeking the cause of the problem, some of the chassidim recalled that the previous Shabbos, the conversation of people in the adjoining room had disturbed him while he was delivering a maamar of Chassidus. He had therefore weakened his sense of hearing in the ear closest to that disturbance.
(תו"מ ח"ז ע' 651, תו"מ תשמ"ח ח"ד ע' 51 הע' 56)
Consider
How can hearing words of Torah affect a person if he doesn’t understand them at all?
