I hear the side A after breakfast and the side B after lunch. I am studying at my home. I found Oxford English Cassettes at a large bookshop in Tokyo. I do not remember when. You can buy various kinds of cassettes at large bookshops in Tokyo, where foreign books are sold.
New cassettes are always difficult.
They are almost unintelligible at first. You do not have to concentrate on cassette though. You will gradually understand them if you continue the hearing practice. Suddenly you will catch a sentence or a paragraph. I do not practice pronunciation.