Smart home and Internet of Things (IoT) are recently drawing attention as the next-generation concept for home appliances. Inexpensive wireless communications technologies for connecting appliances to have enhanced capability and service will be important. This paper proposes the Inaudible Dual Tone Data transmission (IDTD) method, which can be applicable to them based on built-in speakers and microphones. IDTD utilizes an inaudible frequency band of 18kHz or higher in order to minimize discomfort for users. In order to prevent noise, each signal is allotted with dual tone. The proposed method is implemented using a speaker (BNM0026) which is actually applied to appliances. IDTD provides a higher speed and success rate than the existing sound communication systems while keeping the transmission distance is same. This results show feasibility of the data transmission at home appliances without extra hardware.