If you could try to record each individual pair with the same intonation, it would be great. I mean I you say 'bet' with a smile on your face and 'bat' without one, it would be really easy to tell which one is which.
Bet - Bat, Heart - Hot, Not - Nut, Tire - Tower, Caught - Cot, Word - Ward, Leap - Lip
Pool - Book, Cut - Card, Buck - Duck, Breeze - Breathe, Fair - Hair, Gold - Cold - Hold
Sin - Sing, Sheep - Cheap, Sink - Think, Vine -Wine, Masher - Measure
Fair, About, Jump, Yet