The "universal language", which has about 300 registered speakers in Australia, was showcased along with 20 native tongues including Hungarian, Farsi, Korean, Japanese and Kalasha – a derivation of Sanskrit.

Workshops gave an introduction to a language's sound and history, and a little of the country's culture.

“It's basically like a massive taste-testing of languages,” said creative director Richard Delamore. He hopes the festival demonstrated the language diversity that exists around the world and at home, and inspired visitors to reconnect with their heritage.

"Some people might come because their great-grandmother spoke Arabic but it's not in the family any more," Mr Delamore said.

Organisers said almost 300 people attended the Redfern event. A session exploring the Aboriginal languages of Sydney proved popular, attracting more than 30 participants.

The event was sponsored by the Esperanto Federation of NSW and also received support from the Redfern Community Centre.

A separate stream of classes for people interested in linguistics covered topics including fricative consonants (such as the "f" or "th" sounds produced by pushing air out the mouth through a narrow channel) and OzCLO, a national linguistics competition for high school students.

Ramesh and Nuanprae Gopalakrishnan said they shared a general fascination with language and culture, and brought their one-year-old daughter, who they are raising to speak Thai and English.

“It's just interesting to know about different peoples. You never know, in the next few years they might be my neighbours,” said Mr Gopalakrishnan, who also knows a little Tamil and Hindi.

Ms Gopalakrishnan, who speaks fluent German, said all school students should have to learn a second language from day one.

“You gain a different perception of the world,” she said.

After a lunch of two-minute noodles, the day concluded with a multilingual concert featuring songs in Filipino and Russian, and an Esperanto workshop.

Presenter Trevor Steele acknowledged the "universal language" has struggled in Australia.

But he said there may be millions of people worldwide who have had “some contact” with Esperanto.