sndpeek is described as 'is just what it sounds (and looks) like: - real-time 3D animated display/playback - can use mic-input or wav/aiff/snd/raw/mat file (with playback) - time-domain waveform - FFT magnitude spectrum - 3D waterfall plot' and is an app in the Audio & Music category. There are three alternatives to sndpeek for Mac, Online / Web-based and Windows. The best alternative is Spectrum, which is both free and Open Source. Other great apps like sndpeek are Spectro (Free) and Sonic Atom (Paid).
Spectro is a freeware audio file analyzer for windows. Currently capable of reading FLAC, APE, MP3 and WAV files. Spectro lets you view vital data about compressed audio files and creates a spectrogram of the wave data.