The active muffler ACTA^TM

The ACTA^TM is a circular muffler which is placed in ventilation or air-conditionning networks. It replaces standard passive mufflers, and provides high sound attenuation thanks to the use of two technologies :

• electronic active noise control technology to attenuate low frequency noise in ventilation ducts
• passive attenuation technology using glass wool to attenuate medium and high frequency noise.

Strong points

• High attenuation of radiating noise in ducts (airflow and fan noise), mainly low frequency.
• Low charge loss involving less investment in network design and less power consumption.
• Small size, compact system
• Easy installation by simple insertion in the network
• Suitable for new installation or upgrade of existing installation.

Some technical data

• Ducts diameters : from 250 to 630 mm
• Airflow up to 10.000 m3/h. Parallel assembly recommended for higher flows
• No specific maintenance

ACTA^TM principle

A loudspeaker located in the duct emits the cancelling noise which is phase opposed to the primary noise, so that downstream (at the control microphone location) they interfere destructively causing sound attenuation. The system is driven by an electronic calculator. An upstream microphone is also needed to perform the active noise control..

ACTA^TM the industrial product

ACTA^TM PERFORMANCES

Static attenuation

ACTA diameter

Center of octave frequency band

	63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz
250 mm	8 dB	19 dB	26 dB	26 dB	36 dB	50 dB	45 dB	33 dB
315 mm	8 dB	17 dB	21 dB	24 dB	31 dB	41 dB	30 dB	22 dB
355 mm	8 dB	17 dB	21 dB	24 dB	31 dB	41 dB	30 dB	22 dB
400 mm	5 dB	16 dB	18 dB	21 dB	27 dB	41 dB	31 dB	22 dB
450 mm	4 dB	11 dB	19 dB	23 dB	25 dB	33 dB	25 dB	17 dB
500 mm	4 dB	11 dB	19 dB	23 dB	25 dB	33 dB	25 dB	17 dB
560 mm	3 dB	9 dB	12 dB	21 dB	21 dB	25 dB	16 dB	13 dB
630 mm	3 dB	9 dB	12 dB	21 dB	21 dB	25 dB	16 dB	13 dB

Measurement performed following ISO 7235

Dynamic attenuation (Vair = 8m/s)

ACTA diameter

Center of octave frequency band

	63 Hz	125 Hz	250 Hz	500 Hz	1000 Hz	2000 Hz	4000 Hz	8000 Hz
250 mm	10 dB	18 dB	24 dB	26 dB	30 dB	50 dB	45 dB	33 dB
315 mm	8 dB	18 dB	20 dB	22 dB	26 dB	41 dB	30 dB	22 dB
355 mm	8 dB	18 dB	20 dB	22 dB	26 dB	41 dB	30 dB	22 dB
400 mm	8 dB	17 dB	22 dB	23 dB	27 dB	41 dB	31 dB	22 dB
450 mm	4 dB	11 dB	20 dB	24 dB	27 dB	33 dB	25 dB	17 dB
500 mm	4 dB	11 dB	20 dB	24 dB	27 dB	33 dB	25 dB	17 dB
560 mm	4 dB	9 dB	13 dB	20 dB	21 dB	25 dB	16 dB	13 dB
630 mm	4 dB	9 dB	13 dB	20 dB	21 dB	25 dB	16 dB	13 dB

Measurement performed following ISO 7235