Perfect Pitch
I am very fortunate because in one of my first bands there was a guy who played tenor saxophone, while I played bass guitar, and this guy had perfect pitch. When I say perfect pitch, I mean perfect pitch, you can ask this guy to stand on the other side of the room with his back turned towards you and my brother who was on keyboards would play a chord, this guy would not only tell you the notes, he would also tell you what succession they were played.
Now back in the 60′s I used a pitch pipe to tune my bass, and inevitably when you play sometimes you go out of key, having this guy was a blessing, because whenever we would play a gig and you would go out of tune he would assist on tuning you up, which made the task very easy.
Not everyone is going to run across someone like this, that’s why you need to find bass guitar packages that include an electronic tuner to help you tune your bass or electric guitar.