A confusing but interesting study: the researchers taught three gray seals (Halichoerus grypus) to sing. In the demo video below, you can hear the seals learn to imitate and sing some simple phrases. It includes short clips of Star Wars theme melodies (at the beginning) and Little Stars (0:49). Of the three subjects, a seal named Zola was particularly good at imitating melodies, singing melodies with up to 10 notes.

in the video, we always hear a demonstration melody with accurate tone but strange timbre, which is made like this: the researchers first record the natural calls of the seals, then use software to change the frequency of the calls, and then combine them into melodies. This demonstration melody is imitated by seals, and after playing it, they will "sing" their own imitation version. You can tell that these imitations are not perfect, there are still a lot of obvious out-of-tune, but the trend is generally right, and the seals do make a rich change in their voice.

Isn't it marvellous and exhilarating to find a stunning prom dresses under 100 for your event? Immediately after buying, you get a peace of mind.

of course, seals do not sing multiple melodies as soon as they come up. They have undergone a lot of basic training in the early stage, and they have tried more than a thousand times in the first round alone.

the whole training process goes like this:

first, the researchers played the original sound of the seal call, and gave the food reward when the subject seal was willing to follow the call.

then play the tone-altered monosyllabic syllable and reward it when the seal changes its call frequency (it doesn't need to be very accurate. As long as the changing trend is generally matched, you can get a reward)

after the single tone reaches a certain degree of imitation accuracy, the seal begins to train the seal to imitate a short melody composed of multiple tones. Finally, the researchers challenged seals to imitate several basic vowels in human language.

the end result is that the researchers found that seals do have a good ability to imitate sound, and their vocal plasticity is also very strong, although it is not so accurate by human standards.

imitating sound is an ability needed to develop language, and studies like this actually hope to understand how language ability evolved in animals.

related reports and original papers:

https://www.npr.org/2019/06/23/735070681/a-new-hope-seal-learns-to-sing-star-wars-theme

https://www.newscientist.com/article/2207264-seals-have-been-trained-to-sing-the-star-wars-theme-have-a-listen/

https://www.cell.com/current-biology/fulltext/S0960-9822(19)30685-2