In our last post, we broke down why having a quiet space where we could make a lot of noise was important in our line of work. Here we’ll talk more about specific requirements for the vault, how we got there, and what we use the space for today + some cool pictures 🙂

Requirements

There are plenty of room acoustic specifications published by standards bodies to help companies test their products in a repeatable and reliable way. If your company builds phones, you’re likely going to follow specifications and recommendations from ITU and 3GPP. If your company builds Alexa-compatible smart speakers, appliances, etc., you’ll need to follow ETSI room acoustic requirements. Our challenge with the vault was figuring out where the overlap in these requirements was and how we could make our space flexible enough to accommodate a wide variety of product verticals.

The best, most realizable target for our space and budget was to set up an “ETSI Room Plus“. Basically, a room that meets the ETSI standards for voice assistant testing but has an even lower noise floor to be able to do telephony and component level measurements as well. If we could control the reverberation time in specific bandwidths, we could make the space even more flexible for various applications. We also needed to be realistic about the things that we could not do in the space and what our approach would be to mitigate those gaps.

Implementation

Here are some pictures illustrating how we treated the space. We were able to get the broadband noise floor down to 17.53dBA. Significantly lower than the ETSI room requirement of 30dBA but not as quiet as this place (-20.3dBA)!

Current Uses

Some general uses and questions we can answer in this space:

• Evaluating directional sound source effects on a product’s performance: how does your voice assistant capable product behave when an un-intended user utters the keyword (Alexa, etc.) at various distances and angles?
• Evaluating voice quality transmission in a quasi-diffuse field: how does the user of your product sound when they are outside, in a restaurant, etc?
• Evaluating and fine-tuning voice quality for telephony use: how does your conferencing system’s voice quality sound to the person you’re talking to? Can you have a natural conversation, or is it more like a walkie-talkie?
• Are your speaker and microphone component selections adequate for their intended use?

Future Work and More

We’re always looking for scrappy ways to perform accurate and repeatable analysis that informs product feature viability and direction for our clients. The Vault has been a fun foray into what’s possible, and we’re just getting started. Look for more posts about our testing and prototyping efforts coming soon!