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View Full Version : Microphones, rooms and ears - a tale of imperfect transducers



A.S.
03-10-2011, 01:44 PM
Listening to a radio broadcast recently I was reminded how the acoustic space in which the recording was made hugely influences the final sound we hear at home. There is some synergy between the voice to the microphone and the speaker to the listener's ears. In the first case, the further the voice (or instrument) is from the microphone the more the mic captures the contribution of the room. In the second case, the further the listener is from the loudspeakers the more contribution the sound reflected around the room makes. So the common factor in both the recording and replay ends of the chain is the distance between source and transducer.

We can take this a step further. We can make recordings using a selection of microphones at (nearly) exactly the same distance from the source and on replay we will hear a very different tonal colour to the recordings. This is because all microphones have two personalities: the up-close direct signature and the further-away off-axis character where, depending upon factors in the microphone design, more or less of the room's contribution will be audible - possibly even boosted compared with reality.

In the listening room we have the same issue in reverse: the on/off axis behaviour of the loudspeakers will spray the room with sound over at least 180 degrees, and depending upon the dispersion characteristics of the speakers, what the listener inevitably hears is the combination of the loudspeakers' character on and off axis plus the rooms absorption or reflection over 180 degrees in the middle and top frequencies and 360 degrees in the lower ones.

If we agree that there is a strong analogy between sound into the mic and sound from the speakers and the inevitable contribution of the room we can step forward. It's not going to be easy for us to hear (or convenient to measure) the contribution that the listening room makes to the sound we hear at home, but we certainly can demonstrate the influence of on-off axis performance at the other end of the chain by moving the microphone about in the recording studio. The influence of the room - even a studio acoustics - is clear to hear.

Do you follow my thinking on this?

Don Leman
03-10-2011, 05:14 PM
Yes I do Alan and am looking forward to your further thoughts. I believe this is an important factor to often ignored in the listening experience.

Drdennis
04-10-2011, 01:45 PM
Alan,
A variation of this topic came up on the HUG some time ago. I have a BSO recording (SACD) of a Mozart performance I attended. Symphony Hall is considered to be one of the best halls in the world. My subscription seat is 5th row center. The experience of live vs recorded is just different, not better or worse. I have sat in different locations, and I would say the best overall sound is further back at rows 12 to 15, but the volume decreases a bit. There are fewer distractions in my listening room, which I think also makes for a different experience.

DG

A.S.
06-10-2011, 12:08 PM
OK, I'll look out for some examples. I keep hearing them (on the radio) but forget time and date. Must make a concentrated effort to capture some!