NEW YORK » The crisp new signs began going up in some of the most popular spots in Central Park near the end of May. In large white letters on green backgrounds they announce that the areas have been designated Quiet Zones, and that musical instruments and amplified sound are not permitted. Some of the signs cite the authority of the Central Park Conservancy, the private organization that manages the park. Others also bear the name of the city’s Department of Parks and Recreation.

Several musicians who work in the 840-acre park and do not use electronic sound systems said parks enforcement officers had recently ordered them to cease playing or leave certain areas, including Bethesda Fountain, Strawberry Fields and the Boathouse. John Boyd, a singer, said he had refused and received six summonses.

On Sunday afternoon, the civil liberties lawyers Norman Siegel and Geoffrey Croft joined some of those musicians in a passageway next to Bethesda Fountain.

Siegel called the establishment and expansion of the Quiet Zones "antithetical to the principles, values and spirit of the First Amendment."

He said he and Croft would speak with lawyers for the city and ask that the parks officers stop enforcing the rules against people who were not using amplified sound and were not unreasonably loud or causing concern among onlookers.

"Civil liberties are not details or niceties or technicalities," said Arlen Oleson, 56, a hammer dulcimer player who frequents the park. "Civil liberties are the basis of our society."

Several musicians said the money people gave them in the park was their sole source of income. An alto saxophonist, Rakiem Walker, estimated that musicians could earn from $20,000 to $120,000 a year by playing there full time.

Vicki Karp, a spokeswoman for the Parks Department, said the Quiet Zones, some of which date to the 1980s, were introduced as part of an effort to balance competing interests.

"Parks are one of the few places you can come and hear the soothing sounds of nature — bird songs, falling water, the wind in the leaves, human conversation," she wrote in an email. "It is not that we are not allowing music or loud sound. It is that we are also allowing quiet, which isn’t automatic in this city."

She said some signs identifying Quiet Zones had existed in the past. Musicians said the first signs near Bethesda Fountain were put up May 23.

Boyd, 48, who sings opera, gospel, jazz and spirituals and is accompanied by a guitarist, a violinist, a cellist and a flutist, said he began getting summonses — most of them were for unreasonable noise — two months ago, even before the signs went up. He said he planned to fight the summonses in court.

After the news conference, the musicians started to perform, as a crowd gathered. Oleson played a baroque composition by Charles-Hubert Gervais. He finished to applause.

One of those applauding was Rick Eden, 51, an information technology worker visiting from North Smithfield, R.I.

"You do a lot for the environment and the culture," Eden yelled out.