On a day not so many weeks ago if you walked the streets alongside Lafayette Park at noon you might have heard blasting out of a loudspeaker the sounds of whales - mating, splashing around, or dying from harpoon wounds.

To dramatize the "Save The Whale" campaign, a pickup truck carrying Japanese products trailed around the streets surrounding the Park as strong young men leaped onto the roof and viciously plunge harpoons into it.

Lunchers, sitting on benches or stretched out on the grass, listening to see chanties and watching a young lithe dancer in a pale green leotard move beneath a tree as her arms, legs and torso depicted whale noises.

A few days before, Iranian dissidents wearing paper bags over their heads milled about calling President Carter and the shah of Iran a lot of nasty names.

A worker at the Treasury Department whose window faces the park took not. ("They yelled, 'Down with the shah, the shah's a murderer,' over and over again until everyone at Treasury was writing and typing to the rhythm of the chant."

If the demonstrators feel that they can get their message to the occupants of the White House, it's not always so.

"When the doors are open we could hear the people shouting about the shah," said a White House spokesman, "but usually the president is not bothered at all.

Nixon used to peek out the curtains, but Johnson ignored them.

Sam Brown, director of Action and a former antiwar activist, said, "It was a symbolic importance to be in front of the White House. During the bombing of Cambodia there was a 'Clergy Concerned' demonstration and there were about 200 arrests."

Marina Wallach, Washington representative for Soviet Jewry, thinks the park is effective to reach the people and the press. "The cause will be noticed."

Across the dividing line of Pennsylvania Avenue several people bearing signs against the Soviet Union have handcuffed themselves to the White House fence. They are not a part of Wallach's organization. A man with a 6-foot-high sign with hundreds of words in small, tight, lettering begs people to stop and read as he shouts of injustice.

"We sometimes average two demonstrations a day and have had as many as five," said George Berklacy, Park Service spokesman.

"There is not much damage to the park from demonstrators; the biggest damage we get is from squirrels eating the bulbs of plants. There are about a hundred now, where a normal population would be about 25."

The seven acres of Lafayette Park, its design a mixture of a formal style European continental garden and English naturalism, might be, according to Berklacy, "the most expensive front lawn in America."

One hundred and fifty-four years ago the famed Revolutionary war hero Lafayette sort of backed into having a park named after him.

It was in 1824 when Lafayette made a triumphant return to the United States that residents living around what was then "President's Square" began to call it "Lafayette Square."

This name lasted for close to a hundred years until 1933, when control of the National Capitol Parks was returned to the Department of the Interior, and Lafayette Square became Lafayette Park.

In 1791 the government acquired the land, and began to build the "President's House in 1972, taking eight years before turning it over to the Adams family.

President Thomas Jefferson signed papers allowing Pennsylvania Avenue to cut through, thus giving the park to the people.

Over the years the area has been used for laborers' shacks, a race track and a farmers' market. The grounds were used for a grazing pasture by local farmers, British troops camped there during the war of 1812 where they sat and watched the President's House burn. And many a romance has flourished in the park.

Philip Barton Key, the son of Francis Scott Key, may not have been the first man to cross the park in pursuit of romance.

Key would leave his home on Madison Place, cross to Jackson Place where the wife of Rep. Daniel Sickles sneaked him through the door.

Washington, even then a good town for rumors, had this one moving around which eventually got to the ear of Sickles. He loaded his horse pistol and plugged Key as he was 'trolling' through the park one day.

The Bernard Baruch Bench of Inspiration donated by the Boy Scouts of America in 1960 sits under a shady tree, and the other day a man who was definitely out of work and out of sorts, and maybe seeking inspiration, found it a nice spot to curl up and sleep.

They come every day to the park with placards and complaints. They come to play chess. Hundreds stroll the red brick walks to enjoy the flower beds, as junior executives scrimp on box lunches on the way up, and share a bench with a derelict on the way down. Secretaries lie on the grass, eager for a share of the sun they missed on a rainy weekend.

The shopping cart women, pushing their collections of empty bottles and stale bread, call out names for each squirrel.

"Hi, Freddy, I'm here," one shouts hoing he'll respond, but Freddy has a more important matter to tend to, with a begonia bulb in his mouth.

Tourists snap photos of General Jackson, sitting on his horse with his head turned to the White House and waving a salute from his fence on a plot of ground in the center of the park. Their most frequently overheard comment: "That must be Lafayette."