Fair use allows limited use of copyrighted material without permission for purposes such as criticism, commentary, news reporting, teaching, scholarship, or research. To determine if a particular use is fair, courts consider factors like the purpose of the use, the nature of the copyrighted work, the amount used, and the effect on the market for the original work.
Under fair use, using copyrighted material for commercial purposes, reproducing the entire work, and causing financial harm to the copyright owner are prohibited.
When determining if the use of copyrighted material falls under the DMCA Fair Use provisions, key considerations include the purpose of the use (such as for education, criticism, or commentary), the nature of the copyrighted work, the amount of material used, and the effect on the market value of the original work.
You can use copyrighted material without permission when it falls under fair use, which includes purposes such as criticism, commentary, news reporting, teaching, scholarship, or research.
The other people could have been the actual owner of the material and due to that it means they are allowed to upload there own work. However, others could have a licence to use the copyrighted material from the owner of the material. The others also may have found a way to classify it under fair use.
Unless it would fall under "fair use" no it is not "okay" to use copyrighted material without permission
While fair use allows for limited use of copyrighted material without permission under certain conditions, it is still recommended to cite sources when using them in your work. Citing sources helps give credit to the original creators and prevents plagiarism, even if your use may fall under fair use guidelines.
Up to 10% or 1000 words, whichever is less, in the aggregate of a copyrighted work consisting of text material may be reproduced or otherwise incorporated as part of a multimedia project created under Section 2 of these guidelines.
If there is no "fair use" exception the only way to legally use copyrighted material is to obtain permision from the rights holder.
Either find another audio file, one that isn't copyrighted or is free-use, or contact the owner of the copyright and ask them for permission and the conditions under which you can use the material.
Infringement is the use, without permission, of copyrighted material that does not fall under a "fair use" or other exception to copyright law,
If it's copyrighted material, it is illegal to download without paying for it (Amazon, iTunes, etc). However, if it is protected under Creative Commons, then there should be no issue in downloading that material.
Copyright on WikiAnswers is a constant "work-in-progress". As information is entered, updated, and saved it immediately falls under copyright protection.