5. The method of claim 4 , wherein the step of calculating said similarity measure comprises: creating an (N+P−1)×(N+P−1) alignment matrix (D ms ) by setting the character index i of the k-th hypothesis string (a ms :=(Interval 1 , . . . , Interval N-1 , Phoneme 1 , . . . , Phoneme P ) T ) as coordinate for the columns and the character index j of the reference string (b ms :=(Interval 1 , . . . , Interval N-1 , Phoneme 1 , . . . , Phoneme P ) T ) as coordinate for the rows of said matrix and filling the alignment matrix (D ms ) by calculating and setting each (i,j)-element of said matrix according to a filling scheme for filling accumulated cost factors (d i,j =f(d i-1,j , d i,j-1 , d i-1,j-1 , w(a i , b j ))) into the cells of said alignment matrix (D ms ), executing an alignment function based on the Viterbi search algorithm to compare the combined reference string (REF ms ) with the combined hypothesis strings (HYPO ms0 , HYPO ms1 , HYPO ms2 , . . . , HYPO ms,k , . . . , HYPO ms,M+Q−1 ) of all stored melodies and lyrics, thereby returning at least one of a string of characters and a sequence of cost factors (w(a i , b j )) indicating which characters of the combined reference string (REF ms ) closely match with the characters of the k-th combined hypothesis string (HYPO ms,k ), and executing a backtracking algorithm which starts with the lowest cost factor in the last column of the alignment matrix (D ms ) and goes back through the alignment matrix towards the first row and the first column of said matrix along a tracking path derived by the alignment function.
6. The method of claim 5 , wherein the elements (d i,j ) of said alignment matrix (D ms ) are characterized according to the following filling scheme: d ij := min ⁢ { d i - 1 , j + w ⁡ ( a i , 0 ) ∀ i , j ∈ { 1 , 2 , … ⁢ , N + P - 1 } d i - 1 , j - 1 + w ⁡ ( a i , b j ) ∀ i , j ∈ { 1 , 2 , … ⁢ , N + P - 1 } d i , j - 1 + w ⁡ ( 0 , b j ) ∀ i , j ∈ { 1 , 2 , … ⁢ , N + P - 1 } wherein the initial conditions are 
 d 0,0 :=0, 
 d i,0 :=d i-1,0 +w ( a i , 0) ∀ i ε { 1, 2, 3, . . . , N+P− 1}, and 
 d 0,j :=d 0,j-1 +w (0, b j ) ∀ j ε { 1, 2, 3, . . . , N+P− 1}, and wherein w(a i , 0 ) is a cost factor associated with the deletion of the character a i of the k-th hypothesis string (HYPO ms,k ), w( 0 , b j ) is a cost factor associated with the insertion of the character b j into the combined reference string (REF ms ), and w(a i , b j ) is a cost factor associated with the replacement of the element a, of the k-th combined hypothesis string (HYPO ms,k ) by the element b j of the combined reference string (REF ms ), wherein w(a i , b j ) is set to zero if a i =b j and set to a value greater than zero if a i ≠b j .