is there a .pdf of this book

If so could you poste a link to the location.

Nope no PDF sorry.

Few tricks to work on your hearing:

Get 10 coins, most in local currency and a few from another country. Mix them up and grab half without looking. Jingle them in your hand and see if you can tell when you pickup a foreign coin.

Find a narrow hallway with a dead end. Stand a ways away from the end and walk towards it slowly with your eyes closed. Concentrate on hearing when you're about to walk into the wall. There should be some very slight changes in the lingering sounds as you approach the end. This can work in most small areas.

One technique that I was taught by a former Navy Seal can enhance your hearing at a moment's notice. The SEAL's would practice adjusting the air pressure in their heads before exiting a submarine (I think it was before . . anyway,) they would pinch their nose and close their mouth and force air from the lungs up to the mouth, trying to push the air out while tightly keeping the mouth closed. Go ahead, try it . . . you know you want to. Okay, did you notice your ears pop? kind of like when you drive up a steep mountain road . This ear popping enhances my hearing (maybe it just forces some of the wax / dirt etc out from my ears - I don't know) and sounds seem louder. It is completely quiet to perform but requires the use of one hand.
HAMMER

that's what you do on planes when your ears start to hurt