For example, the faintest sound a young person with normal hearing can hear at 2,500 Hz is 0 dB SPL. In contrast, at 20 Hz (a very low frequency sound), the sound needs to be much louder at 72 dB SPL in order to just faintly hear it. … FrequencyHzdB SPLdB HL12545.0025027.0050013.50Understanding the Difference Between Sound Pressure Level … hearinglosshelp.com › blog › understanding-the-difference-between-sound…