Tonight, Mr Alvan Yap will watch the National Day Rally on webcast with his eyes on the sign language interpreter.

The 35-year-old freelance writer needs hearing aids to understand speech. Watching a broadcast without sign language or subtitling is problematic because the sounds are distorted through two electronic media - the TV and his hearing aid.

Tonight's Rally is the first to have real-time sign language translation, allowing the hearing-impaired to catch the most important political speech of the year live.

"It's wonderful and a long time coming," said Mr Yap in an e-mail to The Sunday Times.

He has watched only one Rally; that was in 2010, when he was invited to attend the annual event.

"I had to take my own interpreter along though," he recalled.

President of the Singapore Association for the Deaf Christopher Low said it has been pushing for real-time subtitling and captioning of public speeches for many years.

"This is the first time that there will be live signers for a key broadcast, though there will be no subtitling," he said. "Nevertheless, this is a good start."