The music industry is about to play "Taps" for the vinyl record, its mainstay for 40 years, as compact discs and cassettes combine to supplant the long-playing record album.

"I think records are strictly going to be for the collector," said John Marmaduke, president of Western Merchandisers, a distributor based in Amarillo, Texas, that provides records and tapes to 120 stores it owns as well as another 900 independently owned outlets.In New York, Tower Records, which has what it says is the biggest record store in the nation, says compact discs, which store music in digital form that can be read by laser, have outpaced records for some time.

"We do 50 percent of our business in compact discs," said store assistant manager Howard Cespedes. He estimated that cassettes and records each account for 20 percent of his business.

According to figures from the Recording Industry Association of America, the LP will almost certainly be overtaken in sales this year by the compact disc, which offers near-perfect sound and will never wear out.

The association said that CD sales in terms of units shipped in the first six months of the year rose 64 percent from the same period of 1987 to 70.4 million units, while LP sales fell 22 percent to 43.5 million.

At the current rate, 1988 will be the first full year that record sales will fall behind the high-tech laser disc.

The boom in CDs is everywhere in the industry, including heavy metal heart-throbs such as Guns N' Roses and Def Leppard, although the CD took its foothold in the smaller, but wealthier, classical record market.

"In the classical business, a lot of companies aren't producing records anymore," Cespedes said.

The big problem for the CD industry has been the high prices charged for compact discs - what one record store executive referred to as "price-gouging."

A compact disc retails for about $15, while an LP is typically half that price.

Cespedes noted that prices are coming down. He said that a recent "double album" by the Irish group U-2 was not much higher priced in its CD version since it could be placed on one disc - instead of two records or cassettes.

Marmaduke puts LP sales at just 4 percent of his business. The big winner, cassettes, have 63 percent, while CDs have 16.5 percent. He said LPs are even trailing the 7.5 percent of the business taken by 45 rpm singles.

The only question for industry executives is how long it will all take. While some see the demise of the record soon, Cespedes predicts it will take at least 5 to 10 years.

"There are a lot of vinyl junkies out there," he said.

Bob Altshuler, spokesman for CBS Records, said it was too soon to write off the record completely. "It certainly has been diminishing in sales, but there are 80 million turntables in this country alone," he said.

But he agreed that the LP is on a downward slide, and "it certainly will not rise from that level."

But just as the CD, which has recently gone portable in a bid to kill

the cassette, appears to be gaining ground, the industry is facing a new challenger, the digital audio tape.

Executives differ over whether the DAT will become a new contender or go the way of the eight-track tape. The new cassette offers the sound quality of a compact disc, with the chance to record at home.