Max Mathews of Bell developed the process to digitally record electric analog audio signals via computer in 1957. In 1967, Japan's NHK developed the first mono digital audio recorder.

audio and video player developed by Microsoft and distributed with Microsoft windows

WMA stands for Windows Media Audio. It was developed by Microsoft and is similar to MP3's in that it is a compressed audio format. It generally produces better sound than that of MP3's.

WMA or Windows Media Audio is the audio compression technology developed by Microsoft Corporation. WMA name is given to audio codecs and audio files which use WMA technologies for compression. WMA songs can be stored on CDs and DVDs for playback on PCs and CD/DVD players which support this format. Many of the portable audio players support WMA format playback in addition to MP3 and Real Audio file formats.

There are two names for the tube used in Class A amplifiers developed in the USA. This valve in the US is called vacuum tube audio amplifier. In the UK they are known as valve audio amplifiers.