Sound intensities in hearing aids

[slaw155]

What decibel increase does a hearing aid produce if its sound gathering area is 900cm^2, the area of the eardrum is 0.5cm^2, but it only has an efficiency of 5% in transmitting sound to the eardrum?

I know sound level = 10log(final intensity/initial intensity), but we've only been given areas, so I don't know how to convert these into intensities to find change in sound level?

 

[NascentOxygen]

I think you'll say that the power it collects at the input is transferred across to the output, with an efficiency of 5%.

Q: How is Power related to Intensity?

You don't happen to have been given the correct answer? It's always handy ...

 

[slaw155]

Thanks solved it turns out I made a mistake on my calculator.