What are hinge tones?

Answer 1

I am not sure but hinge tones are also known as target tones.
Jazz guitarists use target tones to easily zero in on important chord tones and to ensure that their improvised solos are melodic and strongly reflect the chord progression. Using the target tone concept simplifies the improvising process, enabling you to play sophisticated lines that resolve beautifully into the correct chord tones - without having to spend 30 years practising hundreds of different scale fingerings!

Answer 2

Various squeaks (?)