Attenuating room reverberation with DSP

[Egoist]

Hi,

I have a room reverberation issue with RT60 times above 1 second. Can I attenuate this issue with DSP?

Thanks

 

[DVDdoug]

Usually not...

If you have a low frequency resonance (room mode), reducing that frequency will lower the resonance/ringing along with the signal and it will sound and measure better.

Does it sound bad to you? If so you probably need some acoustic treatment or just live with it.

 

[Purité Audio]

REW and a microphone.
Keith

 

[Snarfie]

Besides using DSP i listen with farfield colume speakers in a more or less near field listening triangle/position 1.8 meters less influences from walles reflections. result is quite good.

Looks like you can't with DSP according to Minidsp

Acoustic measurements

miniDSP is a leading manufacturer of Digital Audio Signal Processors for the HomeTheater, Hifi, headphone and Automotive market. Join our large community of Audiophiles, Engineers and DIYers using our innovative products.

www.minidsp.com

 

[Pluto]

Hi,

I have a room reverberation issue with RT60 times above 1 second. Can I attenuate this issue with DSP?

Thanks

Short answer, no.

Long answer, errr... no. There are two approaches to this kind of problem

i) absorption, preferably on the walls, to absorb sound energy arriving (and convert it into heat)

ii) diffusion, which breaks up the coherence of reflected sound, thereby making it more tolerable.

A well-considered combination of the two approaches is usually the most expedient and cost-effective.

Most good suppliers of acoustic treatments explain these concepts in greater or lesser depth on their websites.

 

[Purité Audio]

Nice to see you Pluto.
Keith

 

[Pluto]

Ditto -- I have been rather too busy lately to squander time on chat boards; I will give you a call soon - we could have a small beer.

 

[levimax]

Hi,

I have a room reverberation issue with RT60 times above 1 second. Can I attenuate this issue with DSP?

Thanks

Depending on your room you may be able to use a double bass array. You use multiple subs on the front wall and back wall and set the timing so the wave from the front wall is cancelled at the moment it reaches the back wall. If you search this site it appears some members have gotten some very impressive results.

 

[staticV3]

Dirac ART and Trinnov Waveforming are DSP suites which use your speakers as both sound sources and active bass traps to reduce room modes and reverb at lower frequencies.

 

[kemmler3D]

DSP can (sort of ) help with decay time by attenuating a peak in your bass response, but this isn't really changing the decay time so much as lowering a peak that would take longer to decay because it's louder.

Otherwise as others have said it's down to active absorbers (DBA) which are not really DSP but do employ it.

Most of the time you are left with getting some acoustic treatment in there.

 

[dualazmak]

I assume DSP can partially/partly help you, but improvement of room mode/acoustic would be more critical.
These posts on my project thread would be somewhat of your interest and reference, I believe.

- Identification of sound reflecting plane/wall by strong excitation of SP unit and room acoustics: #498

- Measurement of transient characteristics of Yamaha 30 cm woofer JA-3058 in sealed cabinet and Yamaha active sub-woofer YST-SW1000: #495, #497, #503, #507

- Perfect (0.1 msec precision) time alignment of all the SP drivers greatly contributes to amazing disappearance of SPs, tightness and cleanliness of the sound, and superior 3D sound stage: #520

- Not only the precision (0.1 msec level) time alignment over all the SP drivers but also SP facing directions and sound-deadening space behind the SPs plus behind our listening position would be critically important for effective (perfect?) disappearance of speakers: #687

- Reproduction and listening/hearing/feeling sensations to 16 Hz (organ) sound with my DSP-based multichannel multi-SP-driver multi-amplifier fully active stereo audio system having big-heavy active L&R sub-woofers: #782

- A nice smooth-jazz album for bass (low Fq) and higher Fq tonality check and tuning: #910, #63(remote thread)

Spoiler

Just for your reference, please look at my latest Fq-SPL curve measured at my listening position by well calibrated measurement microphone.

 

[AudioJester]

Room shaper can help with base resonances

PLUGINS

Digital room correction plugins

www.homeaudiofidelity.com

 

[Keith_W]

I have a room reverberation issue with RT60 times above 1 second. Can I attenuate this issue with DSP?

Some comments on the RT60. Nearly all of us do not measure the RT60 because it makes no sense in listening rooms for two reasons:

1. We do not get reverberant fields below the transition frequency. We get room modes. So if your "RT60" is 1 sec and you are looking at a room mode, it is NOT a real RT60.
2. The definition of RT60 is the time it takes for sound to decay by 65dB (60dB + 5dB early decay time). The typical noise floor of a listening room is about 40dB, so unless you are measuring at >105dB with an SPL meter, you are not measuring the RT60. You are measuring the noise floor as part of the RT60.

We typically look at the T20 or T30, which removes the "reverberant" component measures the sound to decay by 20dB or 30dB respectively, and this is then extrapolated to T60. Fortunately the extrapolated result is quite accurate since the decay of sound is linear.

Bear in mind that if your measurement was taken improperly - i.e. the sweep was played too soft, or mic not referenced to an SPL meter, it might give you a spurious RT60 result.

Please post your RT60 graph, frequency response, and room dimensions. It will be more helpful.