HMS II.3 LN – Fullband artificial head with very low inherent noise

Front view of the low noise artificial head HMS II.3-LN

The fullband artificial head measurement system HMS II.3 LN allows low-noise...

The fullband artificial head measurement system HMS II.3 LN allows low-noise measurements. Occluded ear simulators with highly sensitive microphones ensure very low inherent noise (16 dB_SPL(A)) with this artificial head variant. This makes HMS II.3 LN the ideal choice for assessing the quality of close-to-the-ear and in-ear audio and communication equipment. Due to the maximum sound pressure level of 148 dB_SPL, the artificial head is also suitable for measurements of far-to-the-ear transducers in hands-free systems, in-car communication systems or smart speaker.

HMS II.3 LN complies with recommendation ITU-T P.57 – including the low-noise requirements in chapter 7. The head and torso simulator provides geometric and acoustic characteristics according to recommendation ITU-T P.58 and thus replicates all acoustically relevant structures of the human anatomy.

HMS II.3 LN enables measurements in sending and receiving direction: While the low-noise occluded ear simulators of the artificial head simulate the receiving direction, a two-way mouth loudspeaker reproduces the complete spectrum of the human voice. This allows narrowband, wideband, super-wideband and fullband measurements to be conducted. With HMS II.3 LN, users can create aurally accurate voice and audio recordings for evaluation with the measurement and analysis software ACQUA.

HMS II.3 LN is characterized by the newly introduced modular concept, which applies to all HEAD acoustics artificial heads in the field of communication and audio testing. From now on, it is possible to use one artificial head for altering applications. Users can quickly and easily change occluded ear simulators and pinnae based on their measurement task.

HMS II.3 LN is ideally suited for low-noise measurements of close-to-the-ear and far-to-the-ear audio and communication devices under realistic conditions.
The fullband artificial head enables binaural recordings to evaluate acoustic scenarios (requires optional occluded ear simulator HIS L LN for the left ear).
HMS II.3 LN complies with recommendations ITU-T P.58, ITU-T P.57 and IEC 60318-4.
Modular concept allows to adapt the artificial head quickly and easily to altering measurement tasks.

Front view of an artificial head HMS II.3 and headphones

Applications

Self-noise measurements of audio devices
Voice quality and audio quality testing of e.g.:
- Mobile phones and handsets
- Headsets, headphones like in-ear buds, and wearables – with and without Active Noise Cancellation (ANC)
- Hearing aids and active/passive hearing protection
- In-vehicle applications like hands-free terminals, in-car communication (ICC) systems, infotainment systems, emergency call (eCall) devices
- Voice-controlled smart home devices like smart speakers and other IoT devices
- Conference phones and hands-free devices

Features

Artificial ears:

HMS II.3 LN is equipped with a low-noise occluded ear simulator in the right ear (HIS R LN) – optionally, it is possible to add a low-noise simulator in the left ear (HIS L LN).
Due to its modular concept, HMS II.3 LN is configurable as desired to fit altering measurement tasks:
- Further variants of the occluded ear simulator are available:
  - Low-noise occluded ear simulators that feature an impedance response matched to that of the human ear for the right ear (HIS R LN HEC) and for the left ear (HIS L LN HEC).
  - Occluded ear simulators for the right ear (HIS R) and for the left ear (HIS L) complying with IEC 60318-4.
- Pinna: HMS II.3 LN is equipped with two anatomically shaped pinnae (ITU-T type 3.3) and can be retrofitted with simplified pinnae (ITU-T type 3.4). Also, human-like designed pinnae (ITU-T type 4.4) that models the section leading into the realistic ear canal are available.
The artificial ears provide a transmission range from 3 Hz to 20 kHz.
The artificial ears ITU-T type 3.3, 3.4 and 4.4 meet the requirements in the recommendation ITU-T P.57 – ITU-T type 4.4 fulfills the low-noise requirements in chapter 7 of ITU-T P.57. Additionally, the occluded ear simulator complies with IEC 60318-4.

Artificial mouth:

The artificial mouth with its two-way loudspeaker design transmits equalized speech signals from 50 Hz up to 20 kHz – from narrowband to fullband.
The two-way mouth simulator of the artificial head also reproduces high speech levels with low distortion.
Acoustic properties of the two-way mouth exceed the requirements of the recommendation ITU-T P.58.
Automated and comfortable equalization of the two-way mouth simulator is supported in the measurement and analysis software ACQUA.

Artificial nose:

HMS II.3 LN can be equipped with an artificial nose (AN-HMS); it enables acoustic measurements of audio and communication devices where a nose ensures secure hold of various devices (e.g. augmented reality glasses, virtual reality headsets).
The height-adjustable tripod HMT III or the torso box HTB VI are different mounting solutions for the artificial head.