Apart from his Musica and his compositions, Hermann enjoyed some notice in musical circles as the originator of a form of letter notation. The notation did not, however, indicate pitch directly but rather intervals. Some of the signs are obvious—s for semitone, t for tone, etc.—while others are less so. Combinations of signs indicate larger intervals. Intervals are assumed to be ascending unless a dot is placed below the symbol, which indicates descent. The scheme is as follows:

This scheme was accompanied by a didactic melody illustrating the intervals and their symbols, which may be seen in example A3.1 below. This notation never caught on, partly because Guido's staff notation rendered it obsolete almost as soon as it had been devised but also because the idea itself is flawed. The notation provides no position-finding mechanism; if a performer makes a mistake, correction is very difficult. The same can be said for a scribe: this notation is very difficult to proofread, and in fact the version of the melody in example A3.1 is taken from A-Wn 2502, which differs considerably from that in A-Wn 51. Transcription from A-Wn 51 has not been successful: it has not been possible to find a starting point from which the intervals notated do not produce pitches outside the medieval Gamut. Furthermore, the compass appears to be very wide. The problem may be a missing (or extraneous) dot—but that is just the point, so to speak. Oesch lists twelve manuscript sources for this piece.

Hermann's description of certain intervals is peculiar, even puzzling. The minor sixth, for example, is described in the song's text as a tritone plus two (minor) semitones.