The Sound of Live Voices

Posted by: Markus on 04 March 2003

Sunday I had the pleasure of listening to the St. Louis Symphony perform Beethoven's Missa Solemnis. Wonderful music performed by a wonderful orchestra!

What surprised me a lot though was the sound of the massed voices, especially the sopranos! If I had been listening to this performance at home I would have thought "oh, my amplifier must be clipping!" since the voices occasionally had a somewhat rough, ragged character. !!! This was, understandably, most apparent on louder passages but often present in the music. Not "troubling", nor did it interfere with my enjoyment of the performance but it did surprise me. Also, there were times when I thought the orchestra was practically "overloading" the room, sonically, similar to what can happen when a good system is played too loud in a smallish room. Also, for those interested, this was from row M in the center parquet. Previous performances I've attended (both in the balcony and also center parquet) have not exhibited these sonic qualities but this was the first time I've heard the St. Louis Symphony Chorale.

Anyone else ever have a similar experience with live, unamplified music?

Markus

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Posted on: 04 March 2003 by paul99
Markus,

I had the same experience during a performanace of Carmina Burana. I was sitting near the front, it was very loud.

The voices when everyone is singing at full blast sounded clipped (similar to, but not quite like, amplifier over-load, more like distortion from a poorly set up cartridge, a sort of crackling sound).

This has bothered me for a long time. I thought that it might be my ears over-loading at first. However, on the HiFi the clipping effect on similar loud choral music is there at all volume levels (only on some recordings).

I came across this explanation which I think my be correct:

Sound is a longitudinal compression/rarefication wave carried by air. There is no limit (within reason) to how high the pressure can go, but there is a lower limit of zero (PSI or bar) pressure. So basically air is a non-liner medium. At high volume levels this comes into effect as incresing non-linerity and eventual clipping on the low-pressure cycles of the sound wave.

This seems to fit with your experience and mine. I have not calculated how loud something needs to be to have a low pressure peak down to zero pressure, I suspect that it is very loud indeed.

What do you think?

Regards,

Paul.
Posted on: 05 March 2003 by JohanR
Many years ago I had the same experience (I very seldom listens to classical music). I then made the conclusion that the voces where amplified by some PA system. But now I know better!

Thanks, ft.

JohanR