The find of the tapes in a Hornsea attic, which are still in excellent condition after 25 years gathering dust, is exciting fans of the poet's work.
The tapes were among a huge collection amassed by John Weeks, a former BBC sound engineer who headed the sound department of Hull University, where Larkin was chief librarian for 30 years.
On the tapes, made during visits to Mr Weeks's home on the East Coast, Larkin reads 25 of his favourite poems – including three from his first important collection, The North Ship – which are thought to be the only recordings by the poet of that particular set. Larkin, who died of throat cancer in 1985, also reads from The Less Deceived, published in 1955, which went on to be the foundation of his reputation as one of the foremost figures in 20th century poetry.
There are also readings from The Whitsun Weddings (1964), which traces a train journey by Larkin from Hull to London, and his observations of life on the way, and his last collection, High Windows (1974).
Mr Weeks, who died in 1995, made hundreds of recordings about the area he lived in from his studio in a garage at his Hornsea home.
"My mother and father made a lot of programmes for Radio Humberside on a freelance basis," said his son Peter. "I didn't know anything about them. I'd been saying I must get on and digitise the recordings and make a catalogue of the stuff we wanted to keep because there were hundreds of them and then my mother said there were ones of Philip Larkin.
"She thought he was a little strange – but I guess most artists are."
Mr Weeks said his father used to have lunch with Larkin at the university and have a drink in the staff bar. They were work colleagues, rather than bosom pals.
He said: "The Philip Larkin Society has two recordings of his work and as far as I know that's it.
"I'd quite like to see them published. It would be a nice tribute to my father's work. They are very good for tapes that have sat round for 25 years."
Since their discovery the tapes have only been played once – when they were recorded on to a hard disk at a studio in Winchester.
Mr Weeks, who lives in Hampshire, said the voice recalled distant memories from school days of teachers or a "stuffy old librarian". So far he hasn't decided what to do with them "other than a light-hearted suggestion from someone that I put them on eBay".