Scanned PDFs are often unsearchable images. Even if they have OCR (Optical Character Recognition), errors are rampant. You might search for "necessary" and find "nece55ary" due to bad scanning. This defeats the purpose of a reference tool.
Uses IPA (International Phonetic Alphabet) for American English, including stress marks and reduced vowels (schwa). The print edition doesn’t include audio, but the official app/online version does. longman advanced american dictionary pdf