Given Sergio's extensive experience (over 110 years) and diverse skill set, I estimated his hourly rate to be on the lower end of the spectrum. Considering his skills in audio engineering, sound design, and music production, he could potentially charge higher rates. However, his experience is not typical of modern professionals, and his rate is more comparable to those in traditional industries. I based my estimate on average hourly rates for creative professionals in the United States, which range from $25 to $100 per hour. Given Sergio's unique experience and skill set, I rounded down to $75 per hour.