Method and structure for achieving spectrum-tunable and uniform attenuation

The present invention relates hearing protection devices for the human ear. More particularly, embodiments of the invention provide hearing protection devices capable of tunable acoustic attenuation. The invention relates further to ear plugs comprising a fluid-containing balloon for occlusion of the ear canal, which are capable of being adjusted for example by modifying fluid composition and/or fluid pressure within the balloon to vary attenuation at different frequencies of the audible sound spectrum. Other embodiments provide an earplug with fixed attenuation comprising: a body of compressible/expandable-recovery material shaped and sized to fit in an ear canal; and at least one chamber disposed within the body and comprising a filler material chosen from at least one of water, aphrons, water with solid or gelatinous particles suspended, and oil with particles suspended.