Helices: Mobile Ear Training App for iOS 3 Devices -
Improve your aural skills with the mobile Helices app.
Identifying frequency content is one of the most important aural skills we feel you need to develop. Helices will help you develop these skills by using standard filters to effect the timbre of a signal. Specifically, you can drill using three filter types over a nine octave range. $0.99.
Fig. 1 Boost filter
Fig. 2 Cut filter
Fig. 3 Bandpass filter