You probably heard Seventh Symphony D. D. Shostakovich. The middle section of the first part depicts the Nazi invasion. Very quietly starts to sound a little primitive melody with a monotonous rhythm. It is repeated many times, each time louder, more and more tools. She grows to giant size, creating the image of the soulless, inhuman strength, which is underway, aiming to crush, to destroy all living things. Such an impression, the composer achieves by means of reception of ostinato.
D. Shostakovich. Symphony No. 7 "Leningrad". The theme of invasion
This method was used in "Bolero" by Ravel, where repeated one subject only in a different orchestration with increasing sonority.
M. Ravel. Bolero
Performed by the London Symphony orchestra
The Italian word "ostinato" (ostinato) means obstinate, stubborn. In the music of the so-called special reception, which is repeated several times the same melodic turn or rhythmic figure. It can be used to convey the state of anxious wait to paint a comic situation, etc.