If stunned silences could be measured in decibels, this one would register someplace off the scale.

There have been plenty of loud and less-than happy reactions to President Carter's decision to revamp and resubmit to Congress his fiscal 1981 budget.

But on his decision to cut funding for the National Institutes of Health, there has been mostly silence from Congress and in the great disease lobby that pushes for more biomedical research money.

That reaction is not surprising. For months, warnings came that 1981 would be a tight budget year. Yet, Carter's first budget in January called for an increase in NIH spending. The health lobby was surprised and mildly grateful.

Then, after Carter rewrote the music in the name of slowing inflation and balancing his budget, he cut his NIH proposal in March. But it still came out higher than the skeptics were anticipating.

Thus, the silence. Leave sleeping dogs lie, may be the operating philosophy.

How silent is the silence? Ordinarily at this time of year the Senate Appropriations subcommittee that passes out NIH money would have several dozen requests from senators asking for increases in specific research areas. This year it has five.

"It's remarkably quiet," said Terry L. Lierman, staff director of the Senate Appropriations Committee. "It is almost as though everyone is shellshocked, not quite certain where to start."

Jay Cutler, head of the Coalition for Health Funding, an organization of major health and research associations, said his groups have a sense of "disaster" about the new budget.

Strong words, perhaps, but in a year of restraint and sail-trimming the NIH budget has survived rather well. And indications from Capitol Hill are that the sacred cow of biomedical research is not going to be slaughtered.

This is the situation as the House and Senate Appropriations subcommittees for Labor-HEW finally prepare to move into markup sessions to determine NIH's fiscal 1981 budget.

The original January budget proposed about $3.6 billion, the first presidential increase sought in eight years -- $140 million more than the 1980 appropriation.Carter earmarked the new money for stabilizing the number of research grants for investigators.

The March budget cut $89.6 million from the earlier proposal, with about 65 percent of that coming from the National Cancer Institute (NCI) about the National Heart, Lung and Blood Institute (NHLBI).But that still left NIH with more than it got in 1980.

Additionally, the administration sought cuts of about $40 million from the current 1980 budget. The House and Senate committees, always friendly toward NIH, reacted in the last few weeks by refusing to go along with most of the cuts.

"What you can read from that for the future," said a Senate committee aide, "is that Congress probably won't do much tampering with NIH."

Another staffer, from the House side, said, "Committee members fail to see how research contributes to inflation. So they're finding a lot of good, humanitarian reasons for going forward with research. They feel they'll do irreparable harm to health programs if they cut research money. You just can't tell a scientist to go drive a bus for two years while we straighten out the federal budget."

Similar thinking prevailed at the Department of Health and Human Services (formerly HEW) after the president directed Secretary Patricia Roberts Harris to take a new look and find ways to cut her budget.

"She didn't embrace that new mood, but she was with the president," said one of her advisers.

Harris was strongly committed to the earlier budget that provided for 5,000 new and competing grants. But she also told NIH to look hard for places to cut.

Dr. Donald Fredrickson, the NIH director, looked and found. Of the $89.6 million reduction, $58.2 million would be from NCI and NHLBI -- largely in their authority to put research out on contract.

This experience of revising a presidential budget after it has been sent to Congress is a new one for Washington. But a fascinating nugget, maybe even a lesson, shows up in the fine print.

It may say something about the tendency of the federal bureaucracy to overreach just a bit, to overcalculate its real needs when it seeks appropriations from congress.

NIH will spend $90 million less than it planned on. But the detailed justification NIH sent to Congress steadfastly assures that none of its 1981 programs will suffer from the cuts.