SOUND 2 ADVANCED : Digital electronic ear for ball mills

SOUND 2 ADVANCED : New-generation electronic ear: digital listening for industrial dosing processes

SOUND 2 ADVANCED is a next-generation digital electronic ear. This grinding level indicator is a complete plug & play sonic solution for measuring and controlling the feed rate of ball mills.

This digital listening device is a unique electro-acoustic transducer with advanced functions capable of evaluating and indicating on a screen the fill level of a ball mill to optimise productivity in various industries. It has an ultra-precise measurement system and its algorithms are the most powerful on the market.

Designed to operate in continuous processes, this sonic system was entirely designed and created by HASLER Group. A premium version of this latest-generation electronic ear is also available: discover the SOUND 2 PREMIUM.

View specifications

Technical sheet


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The technology of this digital electronic ear makes it possible to maximise the efficiency of your ball mill in order to improve the performance of cement processes.


The signal from the microphone is processed in real time to ensure greater accuracy in data measurement and analysis.


The DSP systems simplify filters, providing predictable and highly repeatable results (characteristic of digital circuits as opposed to analogue circuits).


The provision of an analogue data output (0/4 … 20 mA) facilitates integration.


Personalised information, such as the fill level, is displayed in real time on a digital screen for greater visibility and precision. 


The provision of an analogue data output (0/4 … 20 mA) simplifies integration.


The SOUND 2 ADVANCED electronic ear is designed to significantly reduce power consumption per ton of product.


The digital ear for ball mills designed by HASLER Group reduces wear on your grinding equipment and its coating.


With more than 35 years of experience in electronic ear design, HASLER Group’s teams are committed to ensuring optimum reliability for your solutions.

Applications of the SOUND 2 ADVANCED electronic ear

The HASLER Group SOUND 2 ADVANCED digital electronic ear was specially developed to provide high-performance listening to control the fill level in ball mills used in:


Cement, building materials…


Minerals, ores, ceramics


Fertilizers, phosphates


Colours, varnishes…

Description of the SOUND 2 ADVANCED electronic ear


The SOUND 2 ADVANCED digital ear for ball mills consists of a microphone and a front screen incorporating software with advanced control algorithms. It is a robust solution specially designed to fulfil the challenging requirements of cement applications:

/ The microphone head is located 4–5 cm from your mill and is protected by a fine mesh covered with a thin plastic film over the foam layer.
/ The microphone is insulated from background noise in the factory.
/ The screen on the front has a waterproof cover to prevent dust getting in and disrupting the response of the electronic ear.

Key features:

/ Acquisition and processing of the digital sound signal
/ LCD display (HMI)
/ Automatic calibration
/ Adapts to the material to be ground
/ Compatible with the previous Sound 1 electronic ears
/ IP65 metal body
/ Multilingual interface
/ Made in France

Installation :

/ Plug & play installation of the SOUND 2 ADVANCED microphone on a ball mill.
/ This mill control system consists of a very sensitive microphone installed near the outlet from chamber 1 of the mill, at the point of impact of the grinding balls and as close as possible to the housing of the mill.
/ The foam on the digital electronic ear should almost touch the outer housing of the mill.

Technical specifications


/ Setting level : de 0 dB à 45 dB
/ Operating frequency range : De 300 Hz à 4600 Hz.
/ Customer voltage output : 0 … 10 V charge minimum de 1 kΩ
/ Customer current output : 0/4 … 20 mA charge maximale de 600 Ω
/ Humidity : Conforme à DIN40040 classe F 95% à 25°C sans condensation
/ EMI tolerance : ±2 kV sur les signaux, ±4 kV sur l’alimentation 220 VAC
/ Case dimensions : Largeur 256 mm, hauteur 260 mm, profondeur 118 mm
/Ingress protection : IP65
/Weight : 2900 g

/ Power:

230 V, AC input: 88 V AC up to 264 V AC.
Frequency: 47 Hz to 63 Hz

/ Temperature :

In operation: -10 °C to +50 °C
Storage: -30 °C to +70 °C

/ Relay contacts:

Switched max. current: 2 A, AC
Switched max. voltage: 24 V DC, 250 V AC
Switched max. power: 125 VA (48 VA)

/ Certification :

General electrical emissions: EN50081-2
General electrical immunity: EN50082-2
Electrical safety: EN61010-1

A premium version of this latest-generation electronic ear is also available. Discover the SOUND 2 PREMIUM.

HASLER Group global support services for dosing solutions


In order to improve the efficiency and availability of your industrial dosing systems, our specialists offer you a full range of services, including:

/ Technical audits, industrial process audits and laboratory tests.

/ On-site services, such as assembly, commissioning, servicing and preventive or corrective maintenance, with or without remote assistance.

/ Supplies of material tests, simulations and dosing precision tests.

/ Revamping, retrofit or upgrade services aiming to:

  • Increase the reliability of your dosing equipment and manage the obsolescence of SCM/RMS automation.
  • Improve your processes by adapting them to new flow or material constraints or production defects (clogging, fusing, precision) and by adapting their operating range (speed 1–100%).
  • Optimise your mechanical equipment, especially in terms of abrasion resistance (belt).

/ Training modules on your solutions to strengthen the skills of your maintenance and production teams.

/ Comprehensive support to advise you and provide you with spare parts including:

Electronic cards (I/O, communication, etc.)
Display and programming consoles
Weight sensors (digital and analogue)
Mechanical components (rollers, drums, extrusion screws, etc.)
Rubber belts
Metal weighing elements
Speed measuring devices (encoders, measuring wheels).