There seems to be some misinformation about perfect pitch and what it is. I find that some people confuse perfect pitch with relative pitch or tone guessing. So, I think it is worth clearing that up.
What is perfect pitch?
Perfect pitch, which is sometimes referred to as absolute pitch, is the ability to name any note by ear without a reference note. If you were to sit down at a piano and play a note to someone with perfect pitch, they would be able to name that note without looking.
What is relative pitch?
Relative pitch is the ability to name an interval. It can also be used to name notes when given a reference pitch. For example, if you were to play a C for someone with relative pitch, then say to them "what is this note?" and play a G, they would be able to name it. They would also be able to tell you that the interval is a perfect fifth. Simply put, relative pitch is the study of intervals.
What is frequency training?
Frequency training, is a term that I made up. I do not know what the official term for it is. Essentially, frequency training is learning to recognize different frequency ranges. This is mostly used in music production. Having a good ear for frequency ranges allows an audio engineer to listen to a song, and know immediately which frequency ranges are conflicting.
I bring this up because some people believe that having perfect pitch allows someone to name any frequency down to the hertz. The reality is that no one can do this, especially in the higher frequencies. Someone with perfect pitch will be able to tell you what note it is, but they may not be able to tell you the exact frequency.