The distinction between 2 moving averages of volume is the factor, which the Volume Oscillator uses. Due to it helps to define if the whole volume trend is rising or falling.
When the Volume Oscillator moves above zero the shorter-term volume, MA has risen above the longer-term volume MA. This means that the short-term volume trend is higher - in other words, it has more volume - than the longer-term volume trend. Falling prices coupled with decreased volume and bullish signals start from increasing prices coupled with increased volume. Thus, if volume shifts upwards as prices fall, or volume decreases as prices rise, the market is considered to be showing signs of basic weakness.
This strategy is based on the factor that rising prices coupled with increased volume means more buyers, which in future lead to an enduring move. In addition, falling prices coupled with rising volume provide fewer buyers.