Interesting apps but no cigar.
Both are ffmpeg front ends, neither will actually extract the audio without conversion, neither will output a set of mono wav files, one for each channel, & neither will output standard .w64 [multi-channel wav format] -- Pazera [which Giovanni kindly suggested] will output regular multichannel wav files [wav formatex], but then you run into Windows wav file size limits Very fast. And speaking of that file size limit, there are actually 2 limits you can run into -- some apps like mov Audio Extractor seem to hit the wall at ~ 2GB, while others will hit the limit at ~ 4GB.
Otherwise Pazera simply passes command line arguments to ffmpeg.exe in what some still call a DOS box, & it is available in a portable version. The GOTD, mov Audio Extractor, is almost portable, with a 2nd folder added to [UserName]\ Application Data [XP] or [UserName]\ Appdata\ Roaming [Vista <-> 8.1]. In addition to audio-only output you can convert the whole video file, though in that respect it was slow & a bit non-standard -- that's not good or bad, as for example you may have use for AVC avi files, but they can also give you a lot of problems, so AVC in avi files is generally frowned upon, not listed, & not supported.
That said, both apps were quick extracting & converting audio from a video file -- in the case of mov Audio Extractor when you converted audio only -- so both are very usable if you don't feel like looking for something better. Myself, I usually rely either on Nero [for AAC] or a combo of Avisynth & VirtualDub, sometimes with Avisynth plugins like NicAudio [it converts DTS & AC3 to wav, or .w64]. Then once I have .wav or .w64 I encode that.
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Videohelp.com lists 49 tools in its muxer - demuxer category -- muxer = multiplexer, which means combining the audio & video, & as you'd guess, demuxers do the reverse. Many [most?] video conversion apps can at least demux, as can simple ffmpeg front ends like the free WinFF [though you may have to use command line arguments]. For demuxers or converters it often boils down to if you like the GUI -- mov Audio Extractor is certainly prettier than WinFF. http://www.videohelp.com/tools/sections/video-de-multiplexers
Audio conversion is a different animal from just demuxing a video file, although many differences may only be important if you lean more towards being an audiophile. My biggest quarrel with many conversion tools is that they often add processing without giving you a choice in the matter, e.g. normalization & sometimes compression. Normalization is basically a more complicated way of raising the volume level, but too often IMHO it's set to the highest level possible, with no way to adjust that. If you're just extracting the audio from a music video that's probably fine -- if you intend to mux [combine] the results with video again, normalization at max levels will make it too loud. Software like Soundforge can also use a more complicated method of normalization that can sound better, if that matters to you.
Audio compression reduces the difference in volume between the loudest & quietest portions of an audio file or track -- expansion does the reverse. If there's a big difference -- a large dynamic range -- it sounds better, but, only at high enough volume levels that let you hear the more quiet stuff. Problem is that often you can't raise the volume levels high enough, either because of where you're listening or because your speakers, headphones, or earbuds aren't up to the task. An awful lot of players, software & hardware, offer different levels of compression on-the-fly, so you can keep the full dynamic range in the audio file, adjusting compression in the player to suit you -- that gives you the flexibility to listen to the audio as intended when you can, or keep the neighbors from calling the cops, &/or it might let you watch the same movie on your tablet or using your home theater setup.
There's another potential problem if/when you convert the audio's sample rate... in a nutshell 48/44.1 = 1.08843537414966. If you zoom in to look at an audio file's waveform, the points where there's actual data don't match up when you compare a file at 48000 Hz with one at 44100 Hz. Usually you can avoid extra quality loss simply by avoiding any sample rate conversion when possible, or halve it when it's not. When you can't avoid that conversion, & cutting the rate in half won't work, say when you want to take an audio track from a video, which more often is sampled at 48, & put it on an audio CD, where the spec calls for 44.1, using software that can use something called dithering helps. That capability isn't rare, but you do have to look for it.
Finally, one thing to be aware of when you're working with audio & video is that they use completely different clocks. Hopefully you won't have any problems, but it can help to just be aware of potential issues in case you do. If you take out [demux] the audio that's combined with a video file, & compare it to a pure audio recording, very often they will not match. One way they deal with that is by using the AC3 format with audio packets [think capsules] that may contain a surprising amount of empty space -- like a glass with only a little water in it -- the point being that at the start of each packet the audio's in sync. That sort of thing can sometimes cause timing changes converting &/or trimming, maybe more so with video formats like AVC/H.264, that may not have much timing info to begin with, & is made worse with the many apps that won't handle what timing info is there correctly. Again, hopefully you won't ever have a problem, but if you do, that's something to look into.