Donald Richie calls YOJIMBO (1961) "the best-filmed of any of Kurosawa's pictures". But the sound track is worth studying as well. I have compiled two videos that demonstrate the interaction of sounds and music.
Even though Japanese sound tracks at the time often suffered from fidelity issues, Kurosawa was very conscious of the power of sound design (a term that was yet to be invented). In YOJIMBO there are several percussive sounds that fulfill important narrative functions:
In the beginning, when Sanjuro meets the angry farmer and his son in a tele-photo close-up, the only indication that there is some sign of civilisation around are the steadily repetitive sounds of a hand loom. Kazuo Miyagawa's camera then follows the farmer to the nearby house where his wife is weaving equanimously. This rhythmic sound is accompanying the whole scene (which I have shortened) and gets across the subtext that this is a monotonous life.
Later, the inn-keeper Gon tells Sanjuro about all the people in the village. Some of them are introduced by sounds: We only meet the coffin maker by the sound of his hammer which annoys Gon considerably. The sake brewer who rarely leaves his home is characterized by the drumming of his prayers.
Finally, the town crier Hansuke announces the time by beating two xylophone-like sticks. You can hear all four of these sounds in the clip below:
Masaru Satô picks up many of these sounds in his jaunty and rumbling score. Reportedly, Kurosawa did not want a chambara score in any conventional sense and asked for music in a voodoo idiom.
Satô, a composer who liked to incorporate western popular music and jazz in his film scores, wanted to pay homage to Henry Mancini. Miles away from the lightness of "Moon River" or "Meglio sta sera", his succession of short cues was most likely inspired by Mancini's score for Orson Welles' film noir TOUCH OF EVIL (1958). Given that YOJIMBO is partially based on film noir characters, this assumption is not so farfetched.
In the following clip I have juxtaposed excerpts from both soundtracks:
1. "White Horse Lodge" (YOJIMBO): Here the percussive sounds are easily recognizable within the music
2. "Main Title" (TOUCH OF EVIL): There are similar percussion patterns and low brass and woodwinds.
3. "Ronin Arrives" (YOJIMBO): This is a good example of another characteristic trait that might have been influenced by TOUCH OF EVIL - melodic lines arranged in a very low register throughout.