What’s important is maximizing airflow through the foam
to resonate with the foam
and to transfer the vibration to heat. The thicker the foam
the lower the frequency of absorption
, but there are practical limits. Specially formulated open cell foam
such as Studio Pro works best.
I am an acoustic engineer with over 30 years’ experience in the business. My technology has been used in Electric Lady Land Studios, Sony Music of New York, Cello Music and Films founded by Mark Levinson, and Saltmines Studios in Mesa, Arizona, along with hundreds of others.