ML22120TB is a speech synthesis LSI suitable for Acoustic Vehicle Alerting System (AVAS) and sounds outside the vehicle. It is equipped with functions for adjusting playback sounds such as vehicle proximity alert sounds. By changing the pitch and volume of the playback sound, it is possible to comply with the legal requirements for vehicle proximity alert sounds, making it easy to realize vehicle proximity alert sounds. An equalizer function is also provided to simplify sound adjustment after installation in the vehicle and for each vehicle. Furthermore, a failure detection function is provided to detect abnormalities in communication with the main microcontroller or external oscillator, allowing for safe and reliable use.