How to identify a sound issue in Unity?

Question

Audio

Essence of the question: the project was transferred for optimization. The code is written very badly and there are many problems. But recently we added a task: on some system configurations, the sound starts to grind. And moreover, only in the build, and in the editor, no one seemed to be able to reproduce the problem.
Here is the system on which the cant with sound - cs626525.vk.me/v626525277/af20/QcoAZIbHgDY.jpg
Here is the video where the cant is heard - vk.com/video173646263_456239027
Most of the sound is played using PlayOneShot. It is not at all clear what could be causing this and how to fix it. On stage, the average DSP Load is somewhere around 5%, and in the profiler, Audi writes that there are about 30 clips loaded, 103 megabytes, and somewhere around 5-10 active Audio Source.
Do not tell me what could be the problem?