Air-water two phase flows have been characterized using acoustic measurement and sound processing. Analysis is carried in a mini channel of diameter 1.8 mm. Sound of frequency 21500 Hz is emitted using a sound emitter held over the glass tube. A microphone is kept on the other side of the glass tube and acts as the acoustic electric transducer through which the sound signal is acquired using the microphone and is processed using an open source sound processing software AUDACITY 2.0. Filtering and amplification of sound signal is done using the software to study the two phase flow characteristics. Bubbly, Slug and Annular flow regimes are identified. The method can be used to characterize two phase flows without sophisticated instruments.