Sound and Vibration Instrument Hire and Calibration
Bruel & Kjaer 4128 Head and Torso Simulator - HATS
| B&K 4128-C : Bruel & Kjaer Head and Torso Simulator Hire | £120 a day* |
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You can use the B&K HATS free standing, fitted on a tripod, or on a turntable using a tripod mounting adaptor. HATS includes a mouth simulator and Right Ear Simulator Type 4158-C.
A Left Ear Simulator Type 4159-C is available for binaural measurements. HATS has an adjustable neck that allows you to position the head in a realistic posture for different positions of the torso. This is useful in real-life simulations, for example measurements in car seats.
Delivered with individual calibration certificates.
Ear Simulator
Each ear simulator consists of a removable silicon-rubber pinna joined to an ear canal. The ear canal ends in an occluded ear simulator, which simulates the inner part of the ear canal according to the IEC 60318-4 standard. The ear simulator contains a 1/2" microphone and is connected to a microphone preamplifier with an adaptor.
Each ear simulator is delivered with a pinna corresponding to the that specified in ITU-T Rec. P.57 (hardness 35 on the Shore-00 scale). This allows measurements on, for example, handsets using a realistic application force and obtaining a close simulation of an average human acoustic impedance presented to the handset.
The combined influence of the torso, head, pinna and ear-canal on airborne sound signals can be quantified by the acoustic free-field transfer function (the frequency response from free-field to the eardrum).
This is called the Listener free-field frequency response (lfr) or Head Related Transfer Function (HRTF) in telecommunications work, and the Mannequin frequency response in technical audiology.
The typical Listener free-field response of Type 4128-C for sound incident at 0° and the Listener diffuse-field frequency response (dfr) are provided on a USB Drive with the 4128-C.
Mouth Simulator
The B&K HATS mouth simulator has a high-compliance loudspeaker that gives powerful low-frequency response and low distortion. The acoustic transmission path from the loudspeaker to the mouth opening ensures an easily equalized frequency response of the sound pressure level in front of the mouth.
The mouth simulator produces a sound-pressure distribution around the opening of the mouth simulating that of a median adult human mouth, corresponding to the figures given in ITU-T Rec. P.58. An individual equalization procedure ensures a flat frequency response, enabling the mouth simulator to follow the frequency range of human subjects.
Headset Measurements
The ear simulator in Type 4128-C allows accurate measurements to be made on the receiver part of a wireless or corded communications headset. The characteristics of the transmitting part can be measured thanks to the mouth simulator.
Having both a mouth- and an ear simulator, Type 4128-C can also be used for side tone measurements.
Headphone Measurements
You can use Type 4128-C to determine a variety of headphone characteristics in situ. The influence of the pinnae is taken into account and the ear simulators provide the correct acoustic loading, so realistic evaluation of open, closed and insert headphones can be made.
Simulated insertion responses are measured referring to either the equivalent free-field or diffuse-field response. Type 4128-C can also be used to determine the left/right tracking of headphones and their background noise insertion loss.
Hearing Aid Measurements
Both in-the-ear and behind-the-ear hearing aids can be evaluated with Type 4128-C. Two ear mould simulators are supplied with Type 4128-C for testing hearing aids where individually made ear moulds are normally used.
The mouth simulator in Type 4128-C is useful for developing multi-microphone noise-cancelling hearing aids. Simulated insertion gain, simulated directional responses and in-situ maximum output can be measured using HATS, as described in IEC Publication 60118-8.
Vehicles
The sound field in cars and other small enclosures is influenced to a great extent by the physical presence of people in the enclosures. Type 4128-C greatly simplifies representative acoustical measurements under these conditions, enabling more realistic evaluation of vehicle audio systems and mobile telephones, and the effectiveness of measures taken for noise control
Microphones and Hands-free Communications Measurements
When measuring on microphones, Type 4128-C can closely simulate the interaction between the mouth, head, body and microphone. Its mouth simulator is an ideal sound source for the research, development and evaluation of a variety of microphones. In particular, you should use Type 4128-C with close-talking, noise-cancelling and Lavalier types, in which the characteristics of the human voice must be reproduced accurately and the acoustic influence of the head and body is important.
Likewise, the quality of hands-free applications such as video conference and laptop VoIP call technologies can be measured intensively for codec optimisation, side tone tracking, noise cancellation, etc. Type 4128-C enables full duplex operation (simultaneous receive and transmit) for simulation of real-life communication situations
Helmets / Masks
Previously, evaluation and testing of integrated helmet systems, for example communications equipment in crash helmets and gas masks, have been difficult to do realistically. With Type 4128-C, such systems can be thoroughly and realistically investigated with respect to both signals and noise.
The mouth simulator of Type 4128-C replicates the sound field generated by the human mouth even with respect to the frequency-dependent motion of the acoustic-centre in the frequency range important for high-end noise-cancelling microphones.
Hearing Protection Measurements
Evaluating hearing protectors is straightforward using the B&K HATS instead of human subjects. The most important characteristic for hearing protectors is airborne insertion loss. This is found by measuring the free-field response of Type 4128-C with and without the hearing protectors in place and comparing the results.
Type 4128-C can be placed in situ, so the actual noise sources for which the hearing protector is designed can be used in tests. The effectiveness of hearing protectors on noise from different angles is also easy to investigate.
B&K Head & Torso Simulator - Manufacturer's Specifications
Analysers and Accessories
| B&K 2250 | Multi-function Sound Analyser - class 1 |
| B&K 4231 | Sound Calibrator - class 1 |
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* Our standard hire charges are based on a 4-day minimum period, details other options.