Hardware
Browse all details of the hardware used for the Vibravox project.
Subsections of Hardware
Audio sensors
Browse all audio sensors used for the Vibravox project.
Participants wearing the sensors :
Close up on the sensors :
Subsections of Audio sensors
Reference airborne microphone
Reference
The reference of the air conduction microphone is Shure WH20XLR.
This microphone is available for sale at Thomann. The technical documentation can be found here.
Rigid in-ear microphone
Reference
This rigid in-ear microphone is integrated into the Acoustically Transparent Earpieces product manufactured by the German company inear.de.
Technical details are given in AES publication by Denk et al. : A one-size-fits-all earpiece with multiple microphones and drivers for hearing device research.
For the VibraVox dataset, we only used the Knowles SPH1642HT5H-1 top-port MEMS in-ear microphone, the technical documentation for which is available at Knowles.
Soft in-ear microphone
Reference
This microphone is a prototype produced jointly by the Cotral company, the ISL (Institut franco-allemand de recherches de Saint-Louis) and the LMSSC (Laboratoire de Mécanique des Structures et des Systèmes Couplés). It consists of an Alvis mk5 earmold combined with a STMicroelectronics MP34DT01 microphone. Several measures were taken to ensure optimum acoustic sealing for the in-ear microphone, in order to select the most suitable earmold.
Pre-amplification
This microphone required a pre-amplification circuit.
Laryngophone
Reference
The reference of the throat microphone is Dual Transponder Throat Microphone - 3.5mm (1/8") Connector - XVTM822D-D35 manufactured by ixRadio. This microphone is available for sale on ixRadio.
Forehead accelerometer
Reference
To offer a wide variety of body-conduction microphones, we incorporated a Knowles BU23173-000 accelerometer positioned on the forehead and secured in place with a custom 3D-printed headband.
Pre-amplification
A dedicated preamplifier was developed for this particular sensor.
Hold in position
The designed headband is inspired by a headlamp design. A custom 3D-printed piece was necessary to accommodate the sensor to the headband.
Temple vibration pickup
Reference
The reference of the temple contact microphone is C411 manufactured by AKG. This microphone is available for sale on thomann. It is typically used for string instruments but the VibraVox project will use it as a bone conduction microphone.
Hold in position
This microphone was positioned on the temple using a custom 3D-printed piece. The design of this piece was based on a 3D scan of the Aftershokz helmet, with necessary modifications made to accommodate the sensor with a spherical link.
Recorder
Reference
All of the microphones were connected to a Zoom F8n multitrack field recorder for synchronized recording.
Parameters
| Microphone | Track | Trim (dB) | High-pass filter cutoff frequency (Hz) | Input limiter | Phantom powering |
|---|---|---|---|---|---|
| Temple | 1 | 65 | 20 | Advanced mode | ✅ |
| Throat | 2 | 24 | 20 | Advanced mode | ✅ |
| Rigid in-ear | 3 | 20 | 20 | Advanced mode | ✅ |
| Soft in-ear | 5 | 30 | 20 | Advanced mode | ✅ |
| Forehead | 6 | 56 | 20 | Advanced mode | ✅ |
| Airborne | 7 | 52 | 20 | Advanced mode | ❌ |
Sound Spatializer
For all the ambient noise samples used in the dataset, the spatialization process was carried out using Spherebedev 3D sound spatialization sphere developed during Pierre Lecomte’s PhD in our lab, and the ambitools library, also developped by Pierre Lecomte during his PhD at Cnam.
The Spherebedev system is a spherical loudspeaker array with a radius of 1.07 meters, composed of 56 loudspeakers placed around the participants. To ensure precise spatialization in the full range of audio, two nested systems were used:
- A low-frequency system with 6 high-performance loudspeakers (ScanSpeak, up to 200 Hz) for accurate bass reproduction.
- A high-frequency system consisting of 50 loudspeakers (Aura, 2 inches, for frequencies above 200 Hz).
The multichannel audio used for higher order ambisonics resynthesis include third-order ambisonic recordings captured using a Zylia ZM-1S microphone, and a fifth-order ambisonic recordings captured with Memsbedev, a custom prototype ambisonic microphone built in our lab at LMSSC.
