Hofmann-Engl (2001, 2002a, 2002b, 2003a, 2003b, 2004 & 2005) introduced melodic similarity as a combination of melotonic (pitch), chronotonic (durational) and dynamic (loudness distribution)similarity (compare the research resource page).
In 2005, Robert D. Vincent at MC Gill University, Toronto, published a similarity tutorial coining the term Hofmann-Engl similarity referring to melotonic similarity. The tutorial's home page is here.
An applet calculating chronotonic (rhythmic) similarity was not developed. Hence, we are presenting such an applet below. However, the user interface is not very friendly at this point in time.
Firstly, imputing values is not straight forward.
Secondly, the values for k1 and k3 are unclear to a new user. The preset values are the best values as found within one experiment by Hofmann-Engl (2003). It might be an idea to simply keep the preset values unless the user is familiar with the theory behind the algorithm. However, k1 can be viewed as the chrontonic similarity component related to the structure of the two c-chains (rhythms) which are to be compared and k3 with the tempo difference.
Thirdly, there is no proper error protection. For instance, if a user forgets to clear a previous calculation, the following one will be wrong.
Finally, the fragments have to have the same length. For instance, a rhythm (c-chain) can be compared only to another one with 5 notes. Comparing 4 notes with 5 will result in wrong computations.
Nevertheless, this applet at least works even if there is much room for improvement. The rhythms are to be entered best as fractions such as multiples of atomic beats. This is assuming two c-chains are multiples of 16th notes, values are expressed as multiples of 1/16 (e.g.: Rhythm 1: 1/2 1/4 1/4 and Rhythm 2: 1/4 1/4 1/8 1/16 1/16 1/4 are to be inputed as: Rhythm 1: 8 8 8 8 8 8 8 8 4 4 4 4 4 4 4 4 and Rhythm 2: 4 4 4 4 4 4 4 4 2 2 1 1 4 4 4 4. Compare: Rhythmic Similarity. A theoretical and empirical approach, ICMPC 7 (2002))
The program is copyright protected. However, the source code can be found here. The author welcomes suggestions.Ludger Hofmann-Engl © 2008