I applied online. The process took 6 weeks.

The process was long and tedious, as many reviewers on this site have already noted.

Screening:

• First, a recruiter contacted me to schedule a call, which took place after about 1 week from the initial email.
• Next was a 30-minute screening conversation with the hiring manager.
• After that, I was given a test task that looked non-trivial, but I managed to do it relatively easily as I had worked with similar things before. Upon sending them a solution, I was invited to a virtual onsite.
• There was a call with the recruiter again to chat about upcoming onsite logistics.

Onsite: The onsite consisted of 5 interviews:

• A 30-minute welcome interview with one of the senior managers. It was nothing special, just a casual chat.
• There was a cultural fit interview.
• Then an interview on DSP theory. I think I did well, as the questions and case study problem were easy for a DSP professional. I would say it was even too easy for a senior role.
• Next was a coding interview. It felt like a "medium" level problem. I managed to code 2 solutions: a baseline, and then an improved version with better Big-O.
• Finally, an ML interview. There were two people who were talking to me kind of reluctantly. One of them asked with a shade of uncertainty, "Are you interviewing for an Audio DSP role, right?" I said yes, but this didn't help me, as everything we discussed after this had nothing to do with DSP or audio. First, they asked me a couple of trivial ML questions, like "Do you know what is machine learning?" and then jumped to a pretty specific case study problem that was completely detached from any kind of audio or DSP stuff.

Epilogue: After a couple of days, the recruiter contacted me and tried to schedule a call to reject me over the phone, but I preferred chat over email. Anyways, I did appreciate that they provided some real feedback.

Conclusions: Refrain from applying here unless you have a lot of free time and energy and/or it is your last resort. Keep in mind that you can be fooled by the job description, which poorly correlates with the skill set they are looking for.

I cannot disclose the exact questions, but some of them were alike "Have you heard about Machine Learning?"