Updated March 26, 2019 15:33:48

Photo: William Tyrrell was playing in the frontyard of his foster grandmother's home. (Supplied: NSW Police)

William Tyrell's foster mother has described the moment she thought she heard her son scream while searching for him on the day he vanished almost five years ago.

On day two of the inquest into her son's disappearance, the 49-year-old said the noise led her into bushland surrounding his foster grandmother's home at Kendall on the NSW mid-north coast.

"When a child hurts themselves unexpectedly, there's a scream, and it felt like a scream — it was quick and it was high pitched and it was sharp, which is why I went into these reeds," she said.

"I got into the bush and I thought I can't see any red — I thought maybe I imagined it, maybe it was a bird and I just walked back."

Dressed in a Spider-Man suit, the three-year-old was last seen playing in the front yard of the Benaroon Drive property on September 12, 2014.

His foster mother had gone inside to make a cup of tea, and today, she broke down in tears while reliving the shock she experienced when she could no longer hear her son playing joyfully with his older sister.

"I couldn't hear a thing, it was silent, there was no wind, no birds, all I could think of is, 'why can't I hear him? Why can't I hear him? I can't hear a thing'," she told the court.

The woman, who cannot be named for legal reasons, said she frantically searched around "every property" on the street, but could not remember if she "door-knocked" neighbours.

"I remember saying to people I saw, 'I am looking for a little boy in a Spider-Man suit, have you seen him? His name is William'," she said.

After searching the area, the foster mother said she walked back up Benaroon Drive and went inside her mother's house and called police.

"I remember thinking, he's not here, he's not here, I have to call the police — I went inside and grabbed the cordless phone and called triple 0 and I stood exactly in the same spot where I last saw him," she said, wiping away tears.

Photo: An artist's impression of two cars that were parked on Benaroon Drive. (Supplied)

The woman was also questioned about a message she left on the phone of repairman William Spedding about the possibility of fixing her mother's washing machine at the property a few days prior to the disappearance.

Police have previously named Mr Spedding as a person of interest in the investigation, but he has always denied any involvement.

Four neighbours have also testified before the inquest today.

Deputy NSW coroner Harriet Grahame praised the actions of one woman, who got her three-year-old daughter to call out William's name in the hope he would "respond to a little person, rather than an adult".

But none of the witnesses could confirm whether or not two cars — a grey car and white station wagon — were parked on Benaroon Drive on the day the toddler went missing

The inquest continues.

Topics: missing-person, courts-and-trials, kendall-2439, sydney-2000

First posted March 26, 2019 12:44:58