Build an in browser transcription editor

We would like a JavaScript expert freelancer to build for us a prototype in-browser product that provides interactive, assisted transcription of audio files. You should use existing libraries where possible with a focus on developing a working prototype. A user will be able to upload an audio file in their browser. After a few minutes of processing they will then be presented with a possible transcript produced by a speech recognition engine. They will then be able to correct the transcript. The audio will be automatically tracking the user progress so it plays the most relevant audio at all times. They will be able to play the audio file from any point (there will be an audio waveform bar on the bottom of the page that they can click on to go to any arbitrary point in the audio). Clicking on a word will play a short piece of audio, from 1s before the word was said until 4s afterwards, on a loop. The resultant corrected transcript can then be exported to various formats. The target is to minimise the number of keystrokes required to correctly transcribe the audio. Your job will be providing the framework that does the API calls to the speech recognition engine, plays the audio and makes the user experience responsive and intuitive. The user experience is very important in this project – the page needs to feel responsive and intuitive, as well as looking good. Requirements: Proven portfolio of successful UI/UX projects Extensive HTML/CSS/AJAX/Javascript (jQuery, Backbone/Angular/Ember) coding experience CSS compiler knowledge (E.g., Sass, LESS) Experience debugging front-ends Comfortable using modern technologies and interfacing with existing libraries