Fans attending the show at Croke Park blasted engineers via Twitter during the gig for ruining their experience, and many concertgoers walked out because the sound was so bad.
Addressing the issues, Mel shared a video on Instagram in which she pledged to improve the sound quality for the next show.
The 43-year-old, who was make-up free and in bed in the clip, appeared annoyed as she tried to placate disgruntled fans.
"Hey guys thank you for attending our show tonight in Dublin. We will see you in Cardiff and hopefully the vocals and the sound will be much, much better," she explained.
The mother-of-three then made an exasperated, and purposefully audible, sigh.
While Mel acknowledged the sound gaffe, her bandmate Geri Halliwell chose to ignore the backlash to their debut tour performance as she took to Instagram to celebrate their comeback.
The 46-year-old singer shared a snap of herself on stage clad in a red and blue Renaissance-style gown and a shot of herself backstage walking hand-in-hand with her bandmates. "Thank you Dublin! #welove #weserve #wecelebrate #SpiceWorld," she captioned the snaps.
Numerous audience members took to social media to voice their anger over the sound issues, with one Twitter user posting, "Be great if someone could tell the sound people at Spice Girls that the audience can't hear them," while another tweeted, "There's something wrong when the crowd at @spicegirls concert are all sitting down because no one has a clue what song is on because the sound really is THAT bad."
The Spice Girls are scheduled for 12 more shows all over the U.K., with Cardiff's Principality Stadium on Monday, May 27 the next stop on the tour.