After people complained about noise at Taylor Swift's concert in Real Madrid's Bernabeu stadium since it began hosting concerts last month, police measured the volume.

At a Thursday press conference, city hall spokesperson Inmaculada Sanz said the decibel readings must be assessed to determine if they exceeded restrictions. Following the Wednesday night event, authorities received 25 complaints.

Sanz said promoters of past performances that exceeded noise rules will be fined. Sanz did not disclose the decibel measurements, and Real Madrid and Madrid's municipal police declined to comment.

Lastur Booking SL, Taylor Swift's concert promoter, did not reply to calls for comment.

A global superstar performed at the refurbished stadium for tens of thousands of "Swifties," the first. Real Madrid president Florentino Perez has altered the stadium to increase non-football revenue to compete with English Premier League clubs. The 900 million-euro ($978-million) refurbishment included a new roof and a retractable pitch, making the venue an entertainment hub.

However, surrounding people are fed up with the noise and plan to sue to stop it. The Association of Bernabeu Affected People head Enrique Martinez de Azagra said, "We have no choice but to take legal action."

Martinez de Azagra said the association's specialists measured 80 decibels during Wednesday's event, well above the city's 53 decibel limit.

Taylor Swift's concerts on Wednesday and Thursday are likely to help Real Madrid pay off 1.2 billion euros in loans. In 2021, a club source told Reuters that the restoration would boost stadium revenues from 150 million to 400 million euros.