To clearly recognize commands from hosts' voices is important in a smart home device, especially in a smart speaker that plays music at the same time, and when talking to people on the Internet, the echo cancellation capability allows for smooth communication. Both functions depend on the high quality of the reception path through the microphone. The quality will be significantly affected if vibrations from walls and/or device components are transmitted from the operating speakers to the microphones.
We can build a simulation model to predict the situation and then offer solutions to prevent it at the initial design stage.
Figure 1 shows a smart speaker designed with four microphones in an array.
The simulation results indicate that there are significant vibrations at 71 Hz, which will affect the reception quality of the microphones.
Figure 2 shows the initial result of the simulation, where the red area presents the highest displacements (vibrations), while the blue represents the opposite.
There are two solutions that KS suggests to address this situation. The first is to directly modify the plastic walls with more rigid materials. The example here is to use ABSPC to replace the original ABS in all plastic walls of the devices.
Figure 3 shows the simulation results, where vibrations are efficiently suppressed.
Another solution is to add ribs to increase the rigidity of the walls.
Figure 4 shows where the ribs have been added.
Simulating the model after adding the ribs, the result shown in Figure 5 indicates that the vibrations are suppressed and cannot be transmitted to the microphones.
Using appropriate tools to predict design problems and resolve them as early as possible during development can save time and costs, and strengthen competitive power.
Smart speaker tests