Absoption Coefficient: Modulus - Modulus dB // Octave Bands

Hi,

I've made a measurement in a Kundt Tube and obtained the graphic "Teste 04" that shows absorption coefficient "modulus X frequency", however we're interesting in "modulus X frequency bands". How can I get this graphic? The image "Teste_04_Bandas_de_3-8" is a "modulus in dB X frequency bands" and I dont want modulus in dB.

And how can I change the 3/8 bands to 1/8 bands?

I dont know if I was clear with the issues.

Thank you,