Having in mind to be Yotzei: One who desires to fulfill his obligation through hearing someone else’s Havdala must have in mind to do so. The person saying Havdala must likewise have in mind to fulfill the obligation for the listeners.[1] If one heard Havdala without any particular intent[2] then it is disputed whether he has fulfilled his obligation.[3] Practically he may not say Havdala himself although is to try to hear it from someone else.[4] If however one specifically had in mind to not fulfill his obligation with that hearing of Havdala then he may choose to say Havdala himself or hear it from another person.[5] This applies even if the person who said Havdala had in mind not to fulfill his personal obligation and rather said it only for others. In such a case the person who said Havdala would be required to repeat it or hear it from someone else.

Not to answer Baruch Hu Uvaruch Shemo:[6] One who has in mind to fulfill his obligation of Havdala through hearing it from someone else is not to say Baruch Hu Uvrach Shemo upon hearing Hashem’s name said in the blessing. In the event one said Baruch Hu Uvaruch Shemo he is to hear Havdala again from another person.[7]

If one only had in mind to be Yotzei upon hearing the blessing of Hamavdil:[8] Even if one only had in mind to be Yotzei Havdala upon hearing the last blessing of Hamavdil, he nevertheless fulfills his obligation even though he did not have in mind to be Yotzei the blessing of Hagafen. Nevertheless due to this he may not drink any wine after Havdala before saying a blessing of Hagafen. [If one had in mind to not be Yotzei only upon hearing the blessing of Hamavdil, he is to repeat Havdala with exception to the blessing of Meoreiy Haeish.[9]]

Hinei Keil Yeshuasi: It is customary amongst many Chabad Chassidim that those which are listening to Havdala recite these verses quietly to themselves.[10]

Should the listeners say their own blessings of Besamim and Haeish:[11] Those listening to Havdala are to fulfill their blessing with the person saying Havdala[12], and are not to say the blessing over [Besamim or] fire on their own.[13] [This especially applies if the person saying Havdala has already begun the next blessing of Hamavdil in which case all are obligated to listen.[14] Despite the above some are accustomed to say the blessings of Besamim and Meorei Haeish themselves and not rely on the person saying Havdala regarding these blessings.[15] The Rebbe Rashab was accustomed to say the blessing of Hamavdil himself when hearing Havdala said over beer and the like.[16]]

Summary:

One who hears Havdala from another person is to have intent to fulfill his obligation. It is our custom for the listeners to recite the verses of Hinei Keil Yeshuasi quietly to themselves. They are not to answer Baruch Hu Uvaruch Shemo. They are not to repeat their own blessing of Besamim and Haeish and are rather to fulfill their obligation with the person saying Havdala. If one only heard the last blessing of Hamavdil he has nevertheless fulfilled his obligation.

If one heard Havdala and did not have intent to fulfill his obligation but also did not have intent to not fulfill his obligation, then he is to hear Havdala again from another person although he may not say Havdala himself. Thus if one desires to say Havdala himself after hearing someone else say Havdala, such as in Shul, he must have intent not to fulfill his obligation with that person.

Q&A

Is it better to personally say Havdala rather than hear it from another?

It was the custom of the Rebbe Rayatz to always try to fulfill his obligation through hearing Havdala from another person. This was with exception to when he distributed Kos Shel Bracha and Motzei Yom Kippur, in which case he would say Havdala personally.[17] Others have a tradition, to always say Havdala themselves.[18] Some[19] write one should try to say Havdala himself as it is better for one to do the Mitzvah himself rather than through a messenger. All in all, the widespread custom is not to be particular to personally say Havdala, as Berov Am Hadras Melech.[20]

May one stipulate at the time of hearing Havdala that if he later decides to say Havdala himself he will not be Yotzei with the current Havdala that he heard?[21]

Yes.

If one cannot hear the person saying Havdala due to being hard of hearing, or due to his distance from him, may he say the words of Havdala to himself?[22]

Yes. In such a case one may look at the cup of wine in the hands of the person saying Havdala and then say Havdala quietly to himself. Nevertheless if one has wine at home it is better for him in such a case to not fulfill his obligation in Shul.[23]

If one entered in middle of Havdala is he still Yotzei?[24]

So long as he heard the entire blessing of Hamavdil, he has fulfilled his obligation and is to say Besamim and Meoreiy Haeish afterwards. [25] If he entered in middle of the blessing of Hamavdil, he should hear Havdala from another person.[26]

May one repeat Havdala for himself if he was already Yotzei with the Havdala of another person?

No. Once one has fulfilled Havdala through hearing it from another person he may no longer say Havdala.[27] Furthermore even if he did not have in mind to fulfill his obligation but simply heard the blessing he may not say Havdala himself and must rather hear it from someone else.[28] If however one specifically had in mind to not fulfill his obligation with that hearing of Havdala then he may choose to say Havdala himself or hear it from another person.[29]

If one is in middle of Maariv and hears Havdala is he Yotzei?[30]

One who stops to listen to Havdala in middle of his Davening Maariv fulfills his obligation even if he is in middle of Shemoneh Esrei. Nevertheless some Poskim write one is not initially to stop to hear Havdala in middle of Shemoneh Esrei.

Can Havdala be said over loud speaker or Telephone?[31]

No. If one heard Havdala over a telephone he does not fulfill his obligation. If he heard it over a loud speaker than if without the loudspeaker he would not have been able to hear the person saying Havdala, he does not fulfill his obligation.                               

May one hear Havdala from a child?[32]

An adult is not Yotzei if he hears Havdala from a child under Bar Mitzvah. Other children however do fulfill their obligation. Furthermore even if the child is Bar Mitzvah, if he does not yet have a beard, one may not be Yotzei with him unless one knows for certain that the child has already grown two pubic hairs.    

May one hear Havdala from a woman?

No. See Halacha 15!

If there are many people listening to Havdala should they all smell the Besamim and place their fingers by the candle?

Some[33] write it is improper to make a long delay between the blessing of Besamim or Haeish and the continuation of Havdala, and hence in a case of many listeners they should smell the Besamim and bless the fire after Havdala. These blessings may be said even before the person who said Havdala finishes drinking the wine.