People hear different things and sounds are different at different decibels (or something, I don't understand sound mechanics).
Years ago, I was listening to a song by Janne Da Arc (Japanese band) called Stranger. At the end of the chorus I hear a very quiet voice whisper, "3, 2, 1". I told Spunky about this. But when he listened he said the voice whispered "Stranger" and even another friend confirmed this. But try as I might I could only hear "3, 2, 1". It turned into an argument cos he thought I was just being difficult, but it was honestly what I was hearing.
Then, a couple years later, I got a new mp3 player. Listened to that song one day, and very clearly heard "Stranger".
Now, could it have been my mindset, or was it (as I believe) a difference in the settings of the player/speakers?