What are alternations and reproductions?
Alternation is a literal change based on what the following letter is. Reproduction is an addition of a letter to the beginning of the word based on what the last letter of the previous word is.
Each languages seeks to phonetic harmony. Novoslovnica is not an exclusion. For Slavs, harmony lies in presence of vowels every 2-3 letters. This means, that after each 1-2 consonant Slavic hear wants to hear a vowel. If there more than 1-2 consonants, the word becomes unpronouncable and discordant. That's why we have such phenomenon as reproduction of vowels and consonants. Let's look at them.
The reproduction of vowels appears in case, when at the end of a word there is a consonant and also there is a consonant at the beginning of the following word. This makes joint of consonants, that brings discordance in your speach. To avoid it we add into the beginning of the second word a "reproducted" vowels, that makes an additional syllable. This is "Ï" vowel.
For example, the verb "to play" (grati) in many languages sounds like "igrati". So we see the reproducted vowel hear, that became a part of the root. In Novoslovnica we have the verb "grati" and reproducted form "ïgrati".
Similar problem appears when the previous word ends on the vowel and the following also begins from the vowel. We also have no "rotation" of vowels/consonants and now the "reproducted" consonant appears. Novoslovnica has two reproducted consonants - V ans J. Let's show two examples.
The word "eight" originally sounds like "osem/osemj". But many slavic nations brought the reproducred "V" at the beginning of the word as a part of the root - "vosem". Novoslovnica has main form - "osem" and reproducted - "vosem". The second word is "morrow" - "utro". In some languages we can see the form "jutro", that shows us the fact of existing such a vowel in the role of reproducted. So, Novoslovnica has main form "utro" and reproducted - "jutro".
Also we need to talk about the second case - when the letter is reproducted in the end of the first word, not at the beginning of the second. We also have hear a reproducted vowel and reproducted consonant. Often we can see these reproductions in prepositions and short words, in other cases harmony doesn't regenerate in such a way. In Novoslovnica a reproducted end vowel is "o" (K -> Ko) and reproducted end consonant is "b" (O - Ob).
Alternations is the second way to increase harmony of your speech. Alternation means changing of consonants or vowels to make your speech better. Let's talk about different cases of alternations.
This alternation we can see an the end of the words (masculine) while changing it through the cases. K becomes C when after the consonant we see Y sound.
Example: Čelověk - Čelověcy