Ross Geddes suggests (personal communication, 23 May 2006) that at the beginning of this passage the original text may have read “those signs and wonders which they had heard and seen”, just as it does later on in the verse (“all which they had heard and seen”). Since 𝓟 and the 1830 edition agree here near the beginning of the verse in having only heard, if there is an error it must have occurred as Oliver Cowdery took down Joseph Smith’s dictation. The only sign that is given in detail (described in 3 Nephi 1:9–21 as the night that was as bright as day, accompanied by the appearance of a new star) had been physically seen, not heard. These signs and wonders were definitely seen (3 Nephi 1:22), but the later reference in 3 Nephi 2:1 to “all which they had heard and seen” implies that at least some of those signs and wonders had been heard.
Elsewhere the text shows an equal tendency to refer to things that have been perceived by the physical senses as either “seen and heard” (including “heard and seen”) or as simply “seen”. For instance, in relative clauses that refer to things which have been seen or heard, in the original text there are 17 instances that combine see and hear (as at the end of 3 Nephi 2:1). On the other hand, there are 18 instances where the verb see occurs but the verb hear does not. In contrast, there is only one other case of this nature where the verb hear occurs without the verb see. (For these statistics, I include only those cases where the semantics allows for see and hear to co-occur even though only one of the verbs may actually occur.) The one other case with only hear refers to the conversion of the four sons of king Mosiah and what they saw and heard when the angel of the Lord appeared to them (and to Alma, the son of Alma), yet nearby references to that experience include the word see; in fact, we get an example of each possibility (first hear and see together, then see alone, and finally hear alone):
Thus the use of hear alone near the beginning of 3 Nephi 2:1 is not impossible even though overall the signs and wonders referred to in 3 Nephi 1 were “heard and seen”. The critical text will therefore maintain the earliest reading, “and the people began to forget those signs and wonders which they had heard”, the agreed reading of both 𝓟 and the 1830 edition and the likely reading in 𝓞.
Summary: Maintain in 3 Nephi 2:1 the unexpected statement referring to “those signs and wonders which they had heard”, in contrast to the phraseology at the end of the verse (“all which they had heard and seen”); Mosiah 28:1 has a similar reference to hearing alone in its description of what the sons of Mosiah had both heard and seen when the angel of the Lord appeared to them and to Alma, the son of Alma.