Microphone expansion for background noise reduction

A method of controlling the amplification of electrical signals in a telecommunication device having a microphone, the method comprising:

• a) providing electrical signals from the microphone to an amplifier;
• b) employing the amplifier to amplify the electrical signals using one of at least two gain levels, the at least two gain levels including a high gain level and a low gain level;
• c) providing the amplified electrical signals to a transmitter and to a feedback device;
• d) employing the feedback device to determine a relationship between an amplitude of the amplified electrical signals and a predetermined threshold;
• and
• e) causing the amplifier to amplify subsequent signals using the high gain level if the amplitude of the amplified electrical signals exceeds the predetermined threshold.

An apparatus for reducing background noise in a telecommunications device, the telecommunications device including a microphone for receiving acoustic signals, the acoustic signals including voice signals and background noise signals, the microphone being further operable to convert the acoustic signals into corresponding electrical signals, the apparatus comprising:

• (a) an operational amplifier having a first input stage operably connected to receive the electrical signals, a second input stage operably connected to receive the electrical signals, and an output, the operational amplifier operable to provide amplification to the electrical signals to produce amplified electrical signals at the output, said output operably connected to a transmitter for transmitting said amplified electrical signals, the operational amplifier further operable to provide amplification at a first gain level when the first input stage is activated and the second input stage is deactivated, and provide amplification at a second gain level when the second input stage is activated and the first input stage is deactivated;
• (b) a rectifier connected to the output of the operational amplifier, the rectifier operable to receive amplified electrical signals and generate rectified signals therefrom;
• (c) a low pass filter operably connected to the rectifier to receive the rectified signals and operable to generate a dc voltage level therefrom, the dc voltage level representative of a magnitude of the amplified electrical signals;
• and
• (d) a trigger circuit connected to the low pass filter to receive the dc voltage level and further connected to control the activation and deactivation of each of the first input stage and second input stage, and wherein the trigger circuit controllably and alternatively activates and deactivates the first input stage and second input stage depending on whether the dc voltage level exceeds a dc reference voltage level.

An telecommunications device handset operable to reduce background noise, the telecommunications device comprising:

• a) a microphone for receiving acoustic signals, the acoustic signals including voice signals and background noise signals, the microphone operable to convert the acoustic signals into corresponding electrical signals;
• b) an amplifier having an input for receiving the electrical signals and an output, said amplifier operable to receive the corresponding electrical signals from the microphone at said input and provide amplification of the corresponding electrical signals to produce amplified electrical signals at the output, said amplifier operable to provide amplification at a first gain level and a second gain level, said first gain level exceeding the second gain level;
• c) a feedback device connected to the output of the amplifier and further operably connected to control the operation of the amplifier, the feedback device operable to cause the amplifier to provide amplification at the first gain level when the feedback device receives amplified electrical signals at the output having an amplitude above a predetermined threshold and cause the amplifier to provide amplification at the second gain level when the feedback device receives a amplified electrical signals at the output having an amplitude below the predetermined threshold;
• d) means for providing the amplified electrical signals to a telecommunication network;
• e) means for receiving signals from the telecommunication network;
• and
• f) means for presenting the received signals in audio signal form.