SOUND 2 ADVANCED Electronic ear new generation


NEW SOUND 2 numeric electronic ear
Logo de la marque Hasler

Function :

SOUND 2 ADVANCED is a numeric electronic ear new generation.
SOUND 2 ADVANCED is a digital ball mill level indicator able to sense precisely the noise level of the ball mill. This sound system has been imagined & created by HASLER Group.

SOUND 2 ADVANCED is an unique ADVANCED electro-acoustic transducer able to evaluate and show on display the filling level of ball mills. Compared to other basics ears available on the market, Sound 2 ADVANCED shows you the data you have to pilot for more productivity and integrates one of the most accurate measurements and high perfomance algorithms of the market.

The operating noise defines the filling ratio of the ball mill: full mill makes soft & dull sounds or empty mill diffuses loud & high sounds of ball mills.

SOUND 2 ADVANCED is a plug & play digital ball mill level indicator able to sense precisely the noise level of the ball mill. The 2 major advantages of a digital signal compared to an analogue signal are :
Higher precision in measuring, analysing and processing the signal in real time from the microphone.
DSPs simplify filters as they allow predictable and highly repeatable results (characteristic of digital circuits, as opposed to analogue circuits).

SOUND 2 ADVANCED is composed of a microphone and a front panel display integrating a software with advanced control algorithms. Sound 2 ADVANCED is robust and has been developped to meet constraints in cement applications:
● The head of the microphone is 4-5 cm in the rear, and is protected by a fine grid covered by a thin plastic film at the level of the foam coat.
● The microphone is insulated from the interfering noises existing in the plant.
● The front panel display is composed of a watertight cover able to prevent the entrance of dust, which would disturb the response of the electronic ear.

Key benefits

  • High performance to increase productivity of ball mills
  • Numeric data treatment : high precision & process  of the signal
  • Analogic data output (0/4...20 mA)
  • Customized information  front panel display (eg: filling level)
  • Plug & play system & stock available
  • Helps to reduce power consumption per ton of the product
  • Helps to reduce wear of grinding media and lining
  • Over 35 years of experience on electronic ears : product durability & reliability
  • Designed for dusty environment

Key features

  • Numeric signal for sound acquisition and processing
  • LCD screen (HMI)
  • Automatic calibration
  • Adaptation according to the material to be crushed
  • Compatible with previous electronic ear Sound 1
  • IP65 metal body
  • Multi-language interface


The heart of the electronic ear SOUND 2 Advanced is digital & provides accurate measurement.
This system includes an autocalibration function  to ease commisionning. The digital outputs are configurable by the user.
The filling level can be displayed on the LCD screen.
This solution enables you to filter precisely the sound of the ball mill to gain accuracy.


  • Front screen customization accessible via menu

  • Other premium configurations are possible with another solution:
    SOUND 2 PREMIUM version. Please contact us for any further information


  • SOUND 2 ADVANCED’s microphone can be installed «plug & play» on ball mills
  • This mill control system consists in a very sensitive microphone installed close to at the mill inlet, at the grinding ball impact point and as close as possible to the mill shell
  • The foam of the numeric electronic ear must nearly touch the mill shell

Technical specifications

  • Adjustable gain from 0 dB to 45 dB
  • Operating frequency span : 300 Hz to 4600 Hz
  • Voltage output : 0 ... 10 V on minimum 1 kΩ
  • Current output : 0/4 ... 20 mA on a maximum load of 600 Ω
  • Humidity : According to DIN40040 class F 95% at 25°C non-condensing
  • EMI rating: ±2 kV on the signal, ±4 kV on the 220 VAC power supply
  • Case size : Width 256 mm, height 270 mm, depth 118 mm
  • Protection grade : IP65
  • Weight : 2900g.

Power supply

  • 230 V, AC input : 88 VAC until 264 VAC. Frequency : from 47 Hz to 63 Hz


According to IEC 654-1

  • Operating :  -10°C to + 50°C
  • Storage : -30°C to +70°C

Relays contacts

  • Max. switching current : 2 A, AC
  • Max. switching voltage : 24 VDC, 250VAC
  • Max. switching power : 125 VA (48 VA)



  • General Electrical Emissions: EN50081-2
  • General Electrical Immunity: EN50082-2
  • Electrical safety: EN61010-1

Other version

Other premium configurations are possible with another solution. Discover the SOUND 2 PREMIUM version

Download technical sheet