Abstract: A microphone module includes: a microphone element outputting a microphone signal representing collected sound; an amplifier circuit outputting an amplified signal obtained by amplifying a difference between the microphone signal and a reference voltage; a high-pass filter outputting a high-band amplified signal obtained by filtering the amplified signal; a buffer circuit outputting an audio signal obtained by buffering the high-band amplified signal; a first low-pass filter outputting a low-pass bias voltage obtained by filtering the audio signal superimposed on a DC power supply, and a separation circuit outputting an internal bias voltage obtained by removing the influence of an external circuit from the low-pass bias voltage. The second low-pass filter outputs the reference voltage obtained by filtering the internal bias voltage. A circuit from the high-pass filter to the amplifier circuit is set such that an open loop gain is smaller than 0 dB.

Abstract: The present invention relates to aspartame-containing acidic beverages, and also relates to acidic beverages designed to prevent a storage-induced reduction in the sweetness of aspartame, which comprise a polymerized polyphenol (particularly a polymerized catechin). The present invention further relates to a method for preventing a storage-induced reduction in the sweetness of aspartame in aspartame-containing acidic beverages by using a polymerized polyphenol (particularly a polymerized catechin).