This idea is similar in purpose to another idea in this category, which I found during my pre-post search for prior art, but very different in technology and implementation. I think it stands apart and is an improvement over the other idea, but that's not my call as the poster to make, is it? Any MFD experts in the room?
Anyway, here it is:
Pedometers work by sensing movement. Shake them, and they count it. Some advanced pedometers even come with Mp3 players built in, and handlebar-mounted cycling computers can even measure and record cadence.
My idea is for a pedometer or cycling computer that measures cadence to select an appropriate song to match your speed at any given time. Given that people generally walk and run with heavier or lighter steps depending on mood, a sensitive-enough pedometer with the right software should therefor be able to detect moods with a certain degree of accuracy, and use that information combined with the user's cadence to select songs of not only the right tempo, but mood as well.
This could also probably be implemented in the form of a smartphone application using the device's built-in accelerometer, for those who prefer to use their phone for everything. See the Velocomputer app (linked to in the Wiki link I posted) for if you have doubts about a smartphone's accelerometer capabilities. I just downloaded it to my phone to test it, and it friggin' works! Even counts cadence and tells you with a weird voice if your cadence changes, saying 'cadence low' or 'cadence normal' or 'cadence high'.-- 21 Quest, Dec 23 2009 The similar idea. http://www.halfbake...20track_20selection [21 Quest, Dec 23 2009] How pedometers work http://www.wisegeek...-pedometer-work.htm [21 Quest, Dec 23 2009] How cycling computers work http://en.m.wikiped...?wasRedirected=true [21 Quest, Dec 23 2009] settable bpm http://www.halfbake...idea/settable_20bpm"Or just tie it in with a pedometer ..." [phoenix, Dec 23 2009] JogPod http://www.halfbakery.com/idea/JogPod[A] music player with a small motion detection device, so that the beat of the music can be adapted to your jogging speed. [phoenix, Dec 23 2009] Spotify adopting my idea! http://gu.com/p/494gc//Another feature of Spotify’s new version will be “tempo detection”, which the company said will use the phone’s movement sensors to locate a track that will keep pace with a user’s feet when he or she is working out// [21 Quest, May 20 2015] That's actually more thought than I'd put into it, Ian.-- 21 Quest, Dec 23 2009 I could foresee problems with positive feedback.-- coprocephalous, Dec 23 2009 [ian], I don't think [21] was using "cadence" in that technical/music-theory sense.-- bnip, Dec 23 2009 [Ian], the beat, time, or measure of rhythmical motion or activity. (Merriam-Webster's Collegiate Dictionary, 10th ed.)-- bnip, Dec 23 2009 Ian, I was referring to the military's definition of the word, which also is the exercise community's. Cadence is the speed at which you step or pedal. For instance, standard military marching cadence is 2 steps per second. Doubletime is 4 steps per second.-- 21 Quest, Dec 23 2009 //(Merriam-Webster's Collegiate Dictionary//That "dictionary" can't even spell "colour", "centre" or "labour" correctly - I wouldn't trust it as any kind of authority on the English language.-- AbsintheWithoutLeave, Dec 23 2009 Ah, the beautality of words.-- wjt, Dec 23 2009 I think what [IT] is describing is the vowelly-challenged "rhythm".-- AbsintheWithoutLeave, Dec 23 2009 Sounds like a good idea, but how would the player/pedometer know the tempo of a song before it actually starts to play the song?-- bnip, Dec 23 2009 The songs would be selected from a several playlists, each playlist sorted by tempo, mood, and combinations thereof. It may require a dedicated application to choose the appropriate songs from each playlist, and would be easier to do if it just chose from the downloaded music files in your phone, but could also be done by streaming samples from a service like Pandora and matching them to your mood and cadence. Lots of music sites have the option of sorting songs by speed or genre. This is just an extension of that same kind of program.-- 21 Quest, Dec 23 2009 I see. [+]-- bnip, Dec 23 2009 Mood of mover is still going to be tricky. Another data set is going to be needed on top of the cyclic cadence. What would differentiate an angry song with a happy song of same BPM? Bluetooth pressure sensing insoles anyone.-- wjt, Dec 24 2009 From what I read in the pedometer link, some pedometers and fitness trainers actually do integrate with shoe sensors for greater accuracy. Not sure if they use Bluetooth, but some cycling computers, particularly the Velocomputer, definitely do.-- 21 Quest, Dec 24 2009 It is satisfying... But it does the beg the question you mention, with so many music streaming apps available and the widespread adoption by the unwashed masses of accelerometer-equipped smartphones, why HAS this taken so long?-- 21 Quest, May 20 2015 random, halfbakery