Comfortable online meetings

Stress-free telework with voice technology

Audio A/D Converters

Relief for the ”sound” stress of online meetings

The spread of COVID-19 has led the telework as a New Normal way of working. While the burden and stress of commuting and travel have decreased, more and more people are participating in online meetings from their homes, and many people feel stressed by the difficulty of communicating with others compared to face-to-face conversations. One of the reasons for this is the sound problems that tend to occur in online meetings, including the following.

  • The other person cannot understand even when speak in a whisper.
  • Ambient sounds such as household and family conversations are also transmitted.
  • Forget to turn the microphone on and speak.

To avoid these sound problems, you may ask people to be quiet for the duration of the meeting or to move to another room, which may unknowingly cause stress for the family members who live with you. Also, since hearing is more important than sight in online meetings as a means of communicating feelings and emotions, resolving sound problems can lead to smoother communication.This article introduces some of the products and technologies that Asahi Kasei Microdevices contributes to the comfort of online meetings.

Comfortable online meetings with AKM's voice technology

Small voices are clearly recorded

- High Quality Sound Technology -

Support for noise cancellation

- Multi-microphone Recording -

Enable voice detection

- Acousitic Activity Analyzer -

Small voices are clearly recorded

- High Quality Sound Technology -

In online meetings, you often have to speak in a whisper because of the risk of information leaks and concern for those around you. However, have you ever been told that your voice is difficult to hear when you are actually speaking?

One solution is to use a combination of high dynamic range microphones and low-noise A/D converters. AKM's A/D converters for microphones use the same high sound quality technology that has been used in studio recording equipment and other professional audio applications to achieve high signal-to-noise ratios and low distortion.

The A/D converters are capable of capturing small signals clearly without being buried under a noise floor. It also operates on low power consumption, supporting long hours of use in battery-powered applications such as wireless headphones and earphones.

High Quality Sound Technology

Low-noise technology

Low-noise technology

The figure shows a spectrum of the noise floor at 1kHz and -60dBFS with small signal input, with frequency on the horizontal axis and signal strength on the vertical axis.
Low power consumption of only 0.85mW (*1) per channel and dynamic range of 105dB (*2) are achieved.
*1 AK5706 Low Power Mode *2 AK5706 High Performance Mode

Supports for noise cancellation

- Multi-microphone Recording -

Have you ever been embarrassed when the sounds of your life or family conversations are passed through to others?

Therefore, if the microphone can only target and extract the sound in the direction of the speaker, it can remove unwanted sounds from the surroundings.
In such high quality noise-canceling applications as beamforming, increasing the number of microphone channels can result in sharper directivity and higher noise suppression.

AKM has a lineup of A/D converters for multi-microphone recording.

Multi-microphone Recording

Cascade Connection in TDM Mode

Cascade Connection in TDM Mode

It supports the TDM audio format and allows you to build a multi-channel system with up to 16 channels. (AK5704 uses 4 units;  AK5706 uses 8 units.)
The ability to bundle multiple channels of data into a single signal line reduces the number of connection ports required on the SoC.

Enabling voice detection

- Acousitic Activity Analyzer -

It would be more comfortable to have an online meeting if we could control the feature to detect and turn on the user's speech.

For example, have you ever forgotten to turn on the microphone and your speech didn't make it through to the other person at all? If you can turn the microphone on naturally when you speak, you will be able to focus more on the discussion without the need for annoying controls.

Other times when you wear a headset, you may not even notice the calls from your surroundings. Modern headsets have an external sound capturing feature that collects sounds from around you and transmits them to your ears, and if you can turn this feature on when the user speaks, you can start the conversation more naturally.

AKM has developed the AK5706, which integrates Acoustic Activity Analyzer (AAA).The AAA block continuously analyzes incoming audio against user-customized criteria while the rest of the system remains powered off.  It can be used as a voice switch that does not respond to keyboard sounds, but only detects speech.

Acousitic Activity Analyzer

Intelligent wake up

Intelligent wake up

The Acoustic Activity Analyzer operates at an extremely low current consumption of 30uA.
It can be used as a system wakeup trigger to reduce the equipment's standby power.

What is the Acoustic Activity Analyzer (AAA)?

The AAA is more discerning than the typical level-triggered wakeup solution: it performs analog time- and frequency-domain analysis in order to determine whether audio content falls within the specified criteria. AKM's own ultra-low power analog technology (patent pending) enables the AAA to listen for relevant audio while consuming only 30μA.

Acoustic Activity Analyzer (AAA)

The AAA’s Noise Level Detector acts as a gatekeeper: it constantly tracks the ambient noise level in order to reduce false positives that may otherwise occur in a noisy environment. If a sound is louder than the current noise floor by a user-specified delta, the AAA classifies the audio content as low- or high-frequency and short- or long-duration; the criteria for low vs high and short vs long are selected by the user. Human speech is generally low-frequency and long-duration, so a user looking for a wake-word may elect to reject any sounds that fall outside of those parameters. If the product designer wishes to wake the system on a door knock, they may look for low-frequency, short-duration sounds.

Additionally, the AAA has a mode that exclusively detects T3 (smoke detector) and T4 (carbon monoxide detector) alarm sounds.


Product Information

The AK5706ECB is a high-performance 24-bit stereo A / D converter with integrated Acoustic Activity Analyzer (AAA), audio buffer, and support for digital and high-SNR microphones.

The AAA listens for audio activity in a very low-power state while the rest of the device remains powered off. Once qualifying audio content is detected, the audio buffer begins recording and the rest of the AK5706ECB wakes up, in turn waking other devices in the system as needed.

Designed for systems that must listen for specific types of audio activity while consuming very low power, the AK5706ECB is suitable for products such as speech recognition systems, security cameras, and smart doorbells.

The AK5704EN is a high performance analog front-end A / D converter IC suitable for voice recognition, voice control, and conferencing applications.

The device has a built-in 4 channel 32-bit ADC and a low noise microphone amplifier and extracts full performance of a high S / N microphone with low power consumption by achieving dynamic range of 105dB.

It is possible to support up to 16 channel microphone array by connecting multiple AK5704EN’s.

In addition, since it incorporates ultra-low power consumption voice activity detection, power consumption during wait time is greatly reduced.