Pitch = frequency of sound
Sounds may be generally characterized by its pitch, loudness, and quality. The perceived pitch of a sound is just the ear's response to frequency, i.e., for most practical purposes the pitch is just the frequency.
Details about Pitch:
Although for most practical purposes, the pitch of a sound can be said to be simply a measure of its frequency, there are conditions in which a constant frequency sound can be perceived to be changing in pitch.
The perception of the pitch of short pulses differs from that of sustained sounds of the same measured frequency. If a short pulse of a pure tone is decaying in amplitude, it will be perceived to be higher in pitch than an identical pulse which has steady amplitude. Interfering tones or noise can cause an apparent pitch shift.
The number of vibration per second is called the frequency. For example, a long ruler vibrates slowly thus it has a low frequency and gives a low note. A short ruler vibrates more quickly. It has a higher frequency and gives a higher note. To calculate the frequency, one can fix a time interval, count the number of occurrences of the event within that interval then divide the count by the length of the time interval