The Senate Commerce Committee unanimously approved legislation yesterday that would allow airlines to continue using some planes that do not meet stringent new noise standards if they have ordered quiet new planes to replace them.

The measure, sponsored by committee Chairman Howard W.Cannon (DNev.) and several committee members, is designed to encourage the airlines to buy planes using the latest technology -- which are both quieter and more fuel-efficient -- rather than retrofit the old ones.

Cannon contends retrofitting is a waste of money because it doesn't reduce noise appreciably.

Under the bill, an airline could continue to operate for up to three years a plane that doesn't meet new noise abatement standards if it had a signed contract to buy as a replacement one of the quietest of the new planes available.

Under existing Federal Aviation Administration regulations, airlines are required to retrofit or replace twoengine and three-engine jets to meet the standards by Jan. 1, 1983, and fourengine jets by Jan. 1, 1985.

"So for a two-or three -year delay in compliance, we can provide the incentive to acquire an airplane about half as noisy as the aircraft being replaced instead of getting retrofit's meaningless noise reduction," Cannon contended. He said the waivers are necessary to introduce "some rationality" to the FAA's noise regulation. "I'm certainly not against aircraft noise abatement, but I an against throwing money away on noise reductions which don't provide human beings with and relief," he said.

Cannon has been criticizing the retrofit alternative vigorously, especially since a test over Dulles Airport last year. Cannon told the Aero Club in a recent speech that he heard only a slight difference in noise from a retrofitted Boeing 727 and one that wasn't, "which amounted approximately to the difference in irritation between someone running 10 fingernails down a blackboard and then running nine fingernails down the blackboard."

Although he heard a slight difference, he said 30 percent of those at the site could hear no difference or picked the unaltered airplane as being quieter.

Retrofitting a two-engine or three-engine plane is estimated to cost about $250,000.

The legislation, adopted by the committee yesterday on a 15-0 vote, also would give the Transportation secretary discretion to provide waivers for "good cause" to operators who have shown a good-faith effort to comply with the regulations but have fallen short.

Under the bill, the CBA could not impose charges exceeding 2 percent of a domestic ticket, 5 percent on freight (with a maximum $2.25 per 100 pounds of cargo), $2 on tickets to adjacent countries or islands and $10 on tickets to other foreign destinations.

In addition, the measure would require the FAA to carry out its proposal to apply the noise standards to foreign airlines as well as domestic carriers.