The sentence-final rise with intonation for interrogatives in Japanese is produced by maintaining the accent of the word while raising it only on the last mora. It would sound extremely unnatural if the accent pattern of the word is changed. For example, when saying Anata? (あなた？You?) in an interrogative intonation, meaning Anata desu ka? (あなたですか？ Is it you?), the pattern of Low-High-Low with a middle-accent in the word does not change. Only the last mora in the interrogative, i.e. ta, rises after falling. In languages such as English, the intonation in interrogatives rises toward the end of the sentence. Native speakers of Japanese would incorrectly perceive your accent as Low-Low-High if you pronounce anata with its intonation rising toward the end of the sentence. Such an intonation pattern would sound unnatural to native Japanese speakers.
The following diagrams show the change in the pitch of sounds in declaratives and interrogatives by illustrating the examples of an unaccented word, akeru (開ける。to open) and a middle-accented word taberu (食べる。to eat).
The left side of each diagram shows the change in pitch for declaratives of akeru and taberu, while the right shows the change in pitch for the interrogatives of these two words: akeru? 開ける？ and taberu? 食べる？.
From the diagram, we can see that the ake in akeru (開ける) and tabe in taberu (食べる) do not vary much in pitch between declaratives and interrogatives. However, we can see a sharp curve upwards in ru in both words for the interrogatives. Moreover, if we compare the curves of the interrogatives of the two words, we can see that although the ru in akeru? (開ける Open?) rises without any drop in pitch, there is a decline in pitch for ru in taberu? (食べる Eat?) before rising. In other words, the middle-accented pattern of Low-High-Low of taberu (食べる) maintains its accent pattern.
Upon acquiring the rising pattern of interrogatives in Japanese without changing the accent patterns of words, remember to pay attention to the degree and the range of change in the rise in pitch of the last mora. Note that a slow and gradual increase in the last mora will sound as if you are skeptical about what other people are saying, so remember to pay attention to the degree and range of pitch rise as well.