This is the 8801st most frequent Turkish word.
seslar
It seems "seslar" is not a correct Turkish word. Did you mean "sesler"? If so, it means "sounds" or "voices" in English.
Here, 'sesler' refers to 'sounds' in the plural form, used generally for sounds of nature.
Sesler doğanın bir hediyesidir.
Sounds are a gift of nature.
In this context, 'sesler' points to the various noises or voices present in the classroom, emphasizing the plural and diverse nature.
Sınıfın içinde farklı sesler duyuluyordu.
Different sounds were being heard inside the classroom.
Here, 'sesler' is describing the auditory phenomena at the concert, such as music and applause, emphasizing the captivating effect.