App measures and analyses sound pressure level and sound frequency spectrum in real time (RTA) using FFT. It is very easy to use and offers a lot of useful features: high RTA refreshing rate and frequency resolution, adjustable sound pressure level scale (up to 150 dB), RTA peak hold function, flat reference line, local peaks... RTA measurement can be recorded on 3 separate channels. User can later compare SPL and frequency response charts between the channels.It also includes a signal (tone) generator, which helps us measuring the frequency response of a sound system. Input/output can be adjusted to Internal, AUX or Bluetooth. However, all I/O options and combinations do not work on all devices. Microphone can be accurately calibrated for each frequency band separately.It is very easy to use and offers a lot of useful features: high RTA refreshing rate and frequency resolution, adjustable sound pressure level scale (up to 150 dB), RTA peak hold function, flat reference line, local pea

修复部分小错误，提升整体稳定性。