This phenomenon occurs because of the back and forth movement of air molecules around their position of equilibrium in response to the back and forth vibration of an object

A wave in which the vibration of the medium is parallel to the direction the wave travels

T (in seconds) = 1/f (in hertz)

f (in hertz) = 1/T (in seconds)

This inverse relation means that as the frequency increases the period decreases and vice versa

The amplitude change from the positive peak to the negative peak

If the measured value and the reference value = 1, Xmeasured/Xreference = 1, the measured value would be equal to this

AN increase in the density of air molecules which corresponds to an increase in sound pressure

Visual representation or graph in which the pattern of movement is displayed with amplitude as a function of time

The period of pure tones is often measured in this unit of measurement.

the amplitude from baseline (zero) to one of the peaks

This is the upper limit of intensity

A decrease in the density of air molecules corresponds to a decrease in sound pressure

When an object goes through its full range of motion one time

refers to the point along the waveforms cycle where the vibration begins and is expressed in degrees relative to the angle around the circle. Our ears are not sensitive per say at hearing this.

The decrease in a sounds intensity with distance

intensity is inversely (decreases) related to the square of the distance between any two points (D) and is expressed by this formula:

I = 1/D^2

Where D = d(meas)/d(ref)

or with p^2 substituting D

p^2 = 1/D^2, p = 1/D

This amount of dB does not mean the absence of sound it only means that the measured sound intensity is the same as the standard reference intensity.

Some sounds will bounce off an object, whereas other sounds easily go around the object, and depends primarily on this property of the sound.

how many cycles occur in 1 second

the general term to describe the magnitude of a sound. The larger the magnitude the higher this value is.

is actually a measure of power that is distributed over an area and has units of watts/m^2

dB SPL = 20 log(Pmeas microPa / 20 microPa)

when a measured pressure is compared to the standard reference pressure

343 m/s

how long it takes to complete one cycle

This calculation is used to obtain an average amplitude for the waveform and is equal to 0.707 times the peak amplitude

1 - square each of the instantaneous amplitudes to eliminate any negative values

2 - average the squared values

3 - take the square root of the average

the lowest average intensity needed to hear a sound

If the pressure of a sound is doubled it increases by this many dB whereas if the intensity of a sound is double it increases by this many dB