QUESTIONS & Possible Feature Requests

[Matthew J Poes]

Would a measurement such as IACCE3 be relevant to small room acoustics. This is measured with two microphones at a head distance apart or with a dummy head. I've interpreted this data for large room projects, but never small. My thought is that the arrival times are so short in small rooms that the difference would be small and interpretation more difficult, certainly no standards for performance spaces would apply. I know the process would be involved to measure this, but if you could incorporate dual channel capabilities and the ability to measure this, I would have use for it.

Dual channel capability would be good for other reasons, so if that could be added, it would be huge for me. Acoustics is still a hobby, but I do things at a sophisticated enough level that I need what professional software can add.

I want to be able to do in situ measurements of noise floor (so Noise Coefficient measurements) and having NC Curves would be helpful. There are a bunch of different curves now so having all of them as options would be nice. If you do add that, it would be great if it was possible to add a feature that helps people identify their microphone noise floor. For example, the umike noise floor is in the 35-50db range depending on frequency. This limits most of us to pretty basic NC measurements, but for some of us, we could utilize this capability. Realistically, most users don't have noise floors much below 40db's anyway.

I'd also like to do transmission loss measurements and again would like dual channel capability for that. If I could place one microphone in the source room and one in the receiver room, that would allow me measure the response in each space and see not just transmission loss on average but the actual transmission loss by frequency. I would find this especially helpful.

 

[Sonnie]

I have actually attempted measurements using dual ear mics, but never could get it to work. I know Smyth Research has accomplished with their Realizer setup, and I have actually experienced at Axpona. As you stated, not sure if it would really be helpful in a small room situation, but I'd like to know how much our head influences the response.

Maybe John can tell us more about what the capabilities of REW would be with dual mics.

 

[Matthew J Poes]

I have actually attempted measurements using dual ear mics, but never could get it to work. I know Smyth Research has accomplished with their Realizer setup, and I have actually experienced at Axpona. As you stated, not sure if it would really be helpful in a small room situation, but I'd like to know how much our head influences the response.

Maybe John can tell us more about what the capabilities of REW would be with dual mics.

Thanks Sonnie. I hope John will chime in. The measurement I was referencing is a measurement of spaciousness or apparent source width. It's used to evaluate performance spaces, like an opera house. I had a chance to join an acoustical engineer to do measurements in church being converted for dual use (rented for musical performance) and he taught me the measurement. He used a dummy head and dual mics but said dual mics spaced a similar distance would do the same thing. He used a software that could record dual impulse responses, dual channel. I don't think REW is dual channel right?

I thought about taking dual channel measurements by opening two instances of REW, setting one up to measure from an external sound source, and the second to actually supply the impulse and record the other channel. Then process each one and export to excel to analyze the data. I think I could make this work, but it would be a horrific amount of work (I also don't have dual matched measurement mics, but hey, if REW gets this, I'll happily buy them).

 

[John Mulcahy]

Multiple inputs is on the todo list, but I don't expect to get to it any time soon.In the meantime you could use the offline measurement feature to record responses from multiple mics while playing the sweep stimulus and generate measurements from them, one measurement will be generated for each response captured.

 

[Matthew J Poes]

Thanks that was my backup plan.