May one fulfill the blessing through hearing another person reciting it if a Minyan is not present?

Yes. There is no requirement to have a Minyan present in order to be Yotzei a blessing with another person.[1] Nonetheless, when a Minyan is not present, it is better for each person to say their own blessing rather than be Yotzei with another person.[2]

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[1] Admur 59/4 “An individual may not be Motzi another individual with a blessing with exception to Birchas Hanehnin and Birchas Hamitzvos. And the like of all other blessings, however by Birchas Shema and Birchas Hashevach, a Minyan is required”; Admur 8/11 “If a few people are wearing the Tallis simultaneously, each one says their own blessing each person is to say the blessing on his own, although if they want, they can choose to have one person say the blessing, and the remainder will listen and answer Amen.” 213/6 reagrding iof a Minyan is not present by Megillah reading, it is still better for one person to read and say the blessing on behalf of all; M”A ibid and Admur 8/11 and 213/6 never conditions being Yotzei with someone on a Minyan being present

The ruling in Admur here 489/1: Admur 489/1 writes that one may be Yotzei with the blessing of the Chazan being that “As when there are ten Jews doing a Mitzvah together one Jew is able/allowed to say the blessing on behalf of all the congregants, as explained in 8/11.” This implies that if a Minyan is not present [ten Jews] then one may not be Yotzei, or is not allowed to be Yotzei, with another person’s blessing. This clearly contradicts the notion established in all the other sources in Admur and Poskim that a Minyan is never a prerequisite to being Yotzei a Mitzvah or blessing. To note that in M”A ibid, as well as 8/11 no mention is made of that this is limited to the presence of a Minyan. In truth however, one can explain as follows: Admur here in 489/1 never intended to say that a Minyan is required in order to be Yotzei. Rather the intention is to say that in order for it to be initially allowed to be Yotzei with another rather than say it on one’s own, one needs a Minyan present, as otherwise there is not as much of a Berov Am, and the advantage of increasing in necessary blessings overrides the advantage of Berov Am of less than a Minyan. Only when there is a Minyan do we say the advanatage of Berov Am is equal to the advantage of increasing in necessary blessings, and hence there is no precedence to one over the other. [See Admur 213/6 for a discussion of the advantage of Berov Am versus the advanatage of increasing in necessary blessings] On this Admur ibid intended to say that when there is a Minyan one can choose to be Yotzei with the Chazan, as if there isn’t a Minyan it is better to say it oneself. See more sources for this distiocntion in next footnote.

[2] Admur 489/1 as explained in previous footnote; M”A 213/7 and Tosefta Brachos 6/20 “Ten people who are doing a Mitzvah together”, implying that less than ten does not contain Berov Am; This can also be implied from Admur 8/11 and Michaber 8/5 who rules “If a few people are wearing the Tallis simultaneously, each one says their own blessing each person is to say the blessing on his own, although if they want, they can choose to have one person say the blessing, and the remainder will listen and answer Amen.”, now from the fact that Admur/Michaber plainly stated that each one should say the blessing on their own implies that it is preferable.