Room Correction for Smart Speakers

Abstract: Portable smart speakers with wireless connections have in recent years become more popular. These speakers are often moved to new locations and placed in different positions in different rooms, which affects the sound a listener is hearing from the speaker. These speakers usually have microphones on them, typically used for voice recording. This thesis aims to provide a way to compensate for the speaker position’s effect on the sound (so called room correction) using the microphones on the speaker and the speaker itself. Firstly, the room frequency response is estimated for several different speaker positions in a room. The room frequency response is the frequency response between the speaker and the listener. From these estimates, the relationship between the speaker’s position and the room frequency response is modeled. Secondly,an algorithm that estimates the speaker’s position is developed. The algorithm estimates the position by detecting reflections from nearby walls using the microphones on the speaker. The acquired position estimates are used as input for the room frequency response model, which makes it possible to automatically apply room correction when placing the speaker in new positions. The room correction is shown to correct the room frequency response so that the bass has the same power as the mid- and high frequency sounds from the speaker, which is according to the research aim. Also, the room correction is shown to make the room frequency response vary less with respect to the speaker’s position.