To fabricate an underwater information system using audible sound projected by underwater loudspeaker, it is important to estimate the effects of diving hood and face mask for underwater auditory sensitivity. Measuring the underwater sound pressure levels between inside and outside neoprene hoods, it is clear that the hood material becomes a more effective attenuator as frequency is incresed. The attenuations of the signal show a good agreement with threshold performance increases under the experimental condition touching only forehead to water. It appears from the another experiment, in high frequency region above 2 kHz, that the hearing sensitivity of divers is reduced when they wear a neoprene hood and a diving face mask. On the other hand, in low frequency region below 1 kHz, it can be noted that the hearing sensitivity in a case wearing the hood does not result in any functional change.